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  • 51. Fateh-Alavi, K.
    et al.
    Nunez, M. E.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    The effect of stabilizer concentration on the air-plasma-induced surface oxidation of crosslinked polydimethylsiloxane2002Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 78, nr 1, s. 17-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concentrations of three stabilizers-a hindered phenol (Irganox 1076), a hindered amine light stabilizer (Tinuvin 770) and a bifunctional stabilizer with chain-breaking hindered phenol and secondary amine and hydroperoxide-decomposing sulphide moieties (Irganox 565)-in crosslinked polydimethylsiloxane were varied using swelling solutions of the stabilizers at different concentrations. The concentration of the stabilizer in the rubber was assessed by UV-Vis spectroscopy of Soxhlet and microwave assisted extracts. Irganox 1076 and Tinuvin 770 were soluble in polydimethylsiloxane to at least 0.2-0.3 wt.%, whereas the solubility of Irganox 565 was considerably lower. The samples were exposed to GHz air plasma and the surface structures of the exposed samples were studied by X-ray photoelectron spectroscopy, and by optical and scanning electron microscopy after uniaxial stretching. The plasma exposure time required for the formation of an oxidised glassy layer increased in a linear fashion with increasing stabilizer concentration, suggesting that the consumption rate was constant in time during the plasma exposure. Tinuvin 770 showed the strongest overall protecting effect whereas Irganox 565 showed the strongest protecting effect per mass fraction of stabilizer. Irganox 1076 was of moderate efficiency. The results suggest that efficient protection towards air plasma is achieved with hindered amine stabilizers or with stabilizers combining chain-breaking and hydroperoxide-decomposing functions. Differential scanning calorimetry showed that Tinuvin 770 and Irganox 565 protected polydimethylsiloxane against thermal oxidation at elevated temperatures. The chemical consumption of these stabilizers followed basically the classical scheme with zero-order kinetics and a rate constant obeying the Arrhenius law.

  • 52.
    Fateh-Alavi, Kamyar
    et al.
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner, Polymerteknologi.
    A rapid microwave-assisted solvent extraction method for assessment of stabilizer concentration in crosslinked polydimethylsiloxane2004Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 93, nr 5, s. 2185-2192Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crosslinked polyclimethylsiloxanes were prepared containing 0.05 to 0.2 wt % of either a phenolic antioxidant (Irganox(R) 1010) or a hindered amine stabilizer (Tinuvin(R) 144). The stabilizer concentration was assessed by HPLC and UV-Vis spectroscopy of Soxhlet and microwave-assisted solvent extracts. Almost complete recovery of stabilizer was achieved with Soxhlet extraction. High stabilizer recovery was achieved when acetone was used as the solvent in the microwave-assisted extraction. HPLC was shown to be an efficient method for determining the concentration of Irganox 1010. For Tinuvin 144 the selectivity of both UV-Vis spectroscopy and HPLC was poor, leading to imprecise evaluation of the antioxidant concentration. The loss of stabilizer by migration from polymer to hot water (75 and 95degreesC) was monitored for the systems stabilized with Irganox 1010 and the diffusion coefficient of the antioxidant in the polymer was determined.

  • 53. Frostell, Claes
    et al.
    Bjorling, Gunilla
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Aune, Ragnhild E.
    Tracheal implants revisited2017Inngår i: The Lancet, ISSN 0140-6736, E-ISSN 1474-547X, Vol. 389, nr 10075, s. 1191-1191Artikkel i tidsskrift (Fagfellevurdert)
  • 54. Gallet, G.
    et al.
    Carroccio, S.
    Rizzarelli, P.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Thermal degradation of poly(ethylene oxide-propylene oxide-ethylene oxide) triblock copolymer: comparative study by SEC/NMR, SEC/MALDI-TOF-MS and SPME/GC-MS2002Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 43, nr 4, s. 1081-1094Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By comparing size exclusion chromatography/matrix assisted laser desorption ionisation (SEC/MALDI) and SEC/NMR spectra from virgin poly(ethylene oxide-propylene oxide-ethylene oxide) triblock copolymer, we were able to understand the bimodal distribution observed in poloxamer 407. Propylene oxide, isomerised to allyl alcohol during polymerisation, eventually forms a Poly(ethylene oxide-propylene oxide) diblock copolymer when EO is added to the feed. The oxidative thermal degradation of poloxamer 407 at 80 degreesC in air was studied. We found by MALDI that degradation starts after 21 days in the PPO block of the copolymer. This result was confirmed by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS): The first volatile degradation product to appear is 1,2-propanediol,1-acetate,2-formate. The structure of this molecule suggests that a six-ring intramolecular decomposition reaction of the PPO chain occurs at the very beginning of the polymer breakdown. Thus, the secondary hydroperoxide formed on the PPO chain plays a major role on the thermoxidation of poloxamer materials.

  • 55. Gallet, G.
    et al.
    Erlandsson, B.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Thermal oxidation of poly(ethylene oxide-propylene oxide-ethylene oxide) triblock copolymer: focus on low molecular weight degradation products2002Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 77, nr 1, s. 55-66Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The oxidative thermal degradation of poloxamer 407, a poly(ethylene oxide-propylene oxide-ethylene oxide) triblock copolymer, at 50 and 80 degreesC in air was studied by solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS). At 80 degreesC, we found that degradation was initiated on the PPO block of the copolymer by three mechanisms involving hydroperoxyl formation and depropagation. 1,2-propanediol,1-acetate; 1,2-propanediol,2-formate; 1, 2-propanediol,1-acetate, 2-formate and 2-propanone,1-hydroxy were the first degradation products produced. Random chain scissions and a sharp decrease in the molecular weight of the material followed the initiation period. Formic acid and acetic acid, formed upon degradation, participated in esterification reactions leading to the formation of the formate and acetate forms of 1,2-propanediol and ethanediol. Though degradation at 50 degreesC was much slower, the oxidative mechanisms leading to low molecular weight formates and acetates were the same as those observed at 80 degreesC.

  • 56. Gallet, G.
    et al.
    Lempiainen, R.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Characterisation by solid phase microextraction-gas chromatography-mass spectrometry of matrix changes of poly(L-lactide) exposed to outdoor soil environment2000Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 71, nr 1, s. 147-151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Films of poly(L-lactide), PLLA, were buried in outdoor environment in south Finland during two years. The changes in polylactide matrix were characterised by size exclusion chromatography and differential scanning calorimetry, and formation of volatile oligomers was monitored by solid phase microextraction (SPME)-gas chromatography-mass spectrometry. SPME sample preparation was found suitable for analysing small volatile compounds in solid PLLA samples. The oligomers in polylactide were readily extracted with polar CW/DVB fibre. The oligomers were analysed without any complicated sample handling procedure and no solvent was needed. Lactic acid, lactide and lactoyl lactic acid were extracted from the unaged and aged films. Lactide was observed in all films and its content did not change during the two years of soil burial. No lactic acid was observed in any of the polylactide films during the first year. After 20 months lactic acid and lactoyl lactic acid appeared as a result of hydrolysis. After 24 months the amount of lactoyl lactic acid decreased due to biotic hydrolysis of the film. The molecular weight M-n of polylactide increased and the polydispersity decreased during the first year. A slow chemical hydrolysis combined with the migration of small oligomers in soil caused the molecular weight changes for this period. During the second year of soil burial both M-n, and M-w decreased and the polydispersity decreased towards 2. This indicates that a faster hydrolysis took place in the film. It was confirmed by the differential scanning calorimetry analysis of PLLA, which showed that during the second year in soil the thermal properties of the films (T-g and T-m) were affected. PLLA was thus degraded by a combination of hydrolysis and biotic activity. In a first stage, after an induction period of 1 year, the film of PLLA undergoes hydrolysis. In a second stage microorganisms assimilate the small products of degradation while hydrolysis takes place.

  • 57.
    Gil-Castell, O.
    et al.
    Instituto de Tecnología de Materiales (ITM), Universidad Politecnica de Valencia (UPV), Valencia, Spain.
    Badia, J. D.
    Instituto de Tecnología de Materiales (ITM), Universidad Politecnica de Valencia (UPV), Valencia, Spain / Departament d'Enginyeria Química, Escola Tecnica Superior d'Enginyeria, Universitat de Valencia, Burjassot, Spain.
    Kittikorn, T.
    School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH e Royal Institute of Technology, Stockholm, Sweden / Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Songkhla, Thailand.
    Strömberg, E.
    School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH e Royal Institute of Technology, Stockholm, Sweden.
    Ek, M.
    School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH e Royal Institute of Technology, Stockholm, Sweden.
    Karlsson, Sigbritt
    Högskolan i Skövde. School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH e Royal Institute of Technology, Stockholm, Sweden.
    Ribes-Greus, A.
    Instituto de Tecnología de Materiales (ITM), Universidad Politecnica de Valencia (UPV), Valencia, Spain.
    Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites2016Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 132, s. 87-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 degrees C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 degrees C, since it represents the extreme degrading condition. The morphology and crystallinity of the biocomposites were evaluated by means of X-Ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The viscoelastic and thermal performance were assessed by means of dynamic mechanic thermal analysis (DMTA) and thermogravimetry (TGA). The presence of sisal generally diminished the thermal stability of the biocomposites, which was mitigated by the addition of the coupling agent. After composite preparation, the effectiveness of the sisal fibre was improved by the crystallisation of PLA around sisal, which increased the storage modulus and reduced the dampening factor. The presence of the coupling agent strengthened this effect. After hydrothermal ageing, crystallisation was promoted in all biocomposites therefore showing more fragile behaviour evidencing pores and cracks. However, the addition of coupling agent in the formulation of biocomposites contributed in all cases to minimise the effects of hydrothermal ageing. 

  • 58. Gil-Castell, O.
    et al.
    Badia, J. D.
    Kittikorn, Thorsak
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Prince of Songkla University, Thailand.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Skövde University, Sweden.
    Ribes-Greus, A.
    Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites2016Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. The morphology and crystallinity of the biocomposites were evaluated by means of X-Ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The viscoelastic and thermal performance were assessed by means of dynamic mechanic thermal analysis (DMTA) and thermogravimetry (TGA). The presence of sisal generally diminished the thermal stability of the biocomposites, which was mitigated by the addition of the coupling agent. After composite preparation, the effectiveness of the sisal fibre was improved by the crystallisation of PLA around sisal, which increased the storage modulus and reduced the dampening factor. The presence of the coupling agent strengthened this effect. After hydrothermal ageing, crystallisation was promoted in all biocomposites therefore showing more fragile behaviour evidencing pores and cracks. However, the addition of coupling agent in the formulation of biocomposites contributed in all cases to minimise the effects of hydrothermal ageing.

  • 59. Gil-Castell, O.
    et al.
    Badia, J. D.
    Kittikorn, Thorsak
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. Prince of Songkla University Songkhla, Thailand.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Martinez-Felipe, A.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik. University of Skövde, Sweden.
    Ribes-Greus, A.
    Hydrothermal ageing of polylactide/sisal biocomposites. Studies of water absorption behaviour and Physico-Chemical performance2014Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 108, s. 212-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An accelerated hydrothermal degrading test was designed in order to analyse the synergic effect of water and temperature on PLA/sisal biocomposites with and without coupling agent. As well, the physicochemical properties of biocomposites were monitored along the hydrothermal test by means of Scanning Electron Microscopy, Size Exclusion Chromatography and Differential Scanning Calorimetry. The addition of fibre induced higher water absorption capability and promoted physical degradation, as observed in the surface topography. During the processing of biocomposites and throughout the hydrothermal ageing, a reduction of molecular weight due to chain scission was found. As a consequence, a faster formation of crystalline domains in the PIA matrix occurred the higher the amount of fibre was, which acted as a nucleating agent. Higher crystallinity was considered as a barrier against the advance of penetrant and a reduction in the diffusion coefficient was shown. The addition of coupling agent presented a different influence depending on the composition, showing an inflection point around 20% of sisal fibre.

  • 60.
    Gil-Castell, O.
    et al.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València, Valencia, Spain.
    Badia, J. D.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València, Valencia, Spain / Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili, Tarragona, Spain / Departament d’Enginyeria Química, Escola Tècnica Superior d’Enginyeria, Universitat de València, Burjassot, Spain.
    Strömberg, E.
    KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, Stockholm, Sweden.
    Karlsson, Sigbritt
    Högskolan i Skövde. KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, Stockholm, Sweden.
    Ribes-Greus, A.
    Instituto de Tecnología de Materiales (ITM), Universitat Politècnica de València, Valencia, Spain.
    Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, s. 174-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physicochemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches. 

  • 61. Gil-Castell, O.
    et al.
    Badia, J. D.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. Skövde University, Sweden.
    Ribes-Greus, A.
    Effect of the dissolution time into an acid hydrolytic solvent to taylor electrospun nanofibrous polycaprolactone scaffolds2017Inngår i: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 87, s. 174-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hydrolysis of the polycaprolactone (PCL) as a function of the dissolution time in a formic/acetic acid mixture was considered as a method for tailoring the morphology of nanofibrous PCL scaffolds. Hence, the aim of this research was to establish a correlation between the dissolution time of the polymer in the acid solvent with the physico-chemical properties of the electrospun nanofibrous scaffolds and their further service life behaviour. The physico-chemical properties of the scaffolds were assessed in terms of fibre morphology, molar mass and thermal behaviour. A reduction of the molar mass and the lamellar thickness as well as an increase of the crystallinity degree were observed as a function of dissolution time. Bead-free fibres were found after 24 and 48 h of dissolution time, with similar diameter distributions. The decrease of the fibre diameter distributions along with the apparition of beads was especially significant for scaffolds prepared after 72 h and 120 h of dissolution time in the acid mixture. The service life of the obtained devices was evaluated by means of in vitro validation under abiotic physiological conditions. All the scaffolds maintained the nanofibrous structure after 100 days of immersion in water and PBS. The molar mass was barely affected and the crystallinity degree and the lamellar thickness increased along immersion, preventing scaffolds from degradation. Scaffolds prepared after 24 h and 48 h kept their fibre diameters, whereas those prepared after 72 h and 120 h showed a significant reduction. This PCL tailoring procedure to obtain scaffolds that maintain the nanoscaled structure after such long in vitro evaluation will bring new opportunities in the design of long-term biomedical patches.

  • 62.
    Gil-Castell, Oscar
    et al.
    Instituto de Tecnología de Materiales (ITM), Universitat Politecnica de Valencia (UPV), Valencia, Spain.
    Badia, J. D.
    Instituto de Tecnología de Materiales (ITM), Universitat Politecnica de Valencia (UPV), Valencia, Spain / Departament d'Enginyeria Química, Escola Tecnica Superior d'Enginyeria, Universitat de Valencia, Burjassot, Spain.
    Kittikorn, Thorsak
    Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden / Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University Songkhla, Thailand.
    Strömberg, Emma
    Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Martínez-Felipe, Alfonso
    Instituto de Tecnología de Materiales (ITM), Universitat Politecnica de Valencia (UPV), Valencia, Spain / Departamento de Química Organica, Facultad de Ciencias, Instituto de Ciencia de Materiales de Aragon (ICMA), Universidad de Zaragoza-CSIC, Spain.
    Ek, M.
    Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Karlsson, Sigbritt
    Högskolan i Skövde. Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden.
    Ribes-Greus, Amparo
    Instituto de Tecnología de Materiales (ITM), Universitat Politecnica de Valencia (UPV), Spain.
    Hydrothermal ageing of polylactide/sisal biocomposites: Studies of water absorption behaviour and Physico-Chemical performance2014Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 108, nr special issue, s. 212-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An accelerated hydrothermal degrading test was designed in order to analyse the synergic effect of water and temperature on PLA/sisal biocomposites with and without coupling agent. As well, the physicochemical properties of biocomposites were monitored along the hydrothermal test by means of Scanning Electron Microscopy, Size Exclusion Chromatography and Differential Scanning Calorimetry. The addition of fibre induced higher water absorption capability and promoted physical degradation, as observed in the surface topography. During the processing of biocomposites and throughout the hydrothermal ageing, a reduction of molecular weight due to chain scission was found. As a consequence, a faster formation of crystalline domains in the PIA matrix occurred the higher the amount of fibre was, which acted as a nucleating agent. Higher crystallinity was considered as a barrier against the advance of penetrant and a reduction in the diffusion coefficient was shown. The addition of coupling agent presented a different influence depending on the composition, showing an inflection point around 20% of sisal fibre. (C) 2014 Elsevier Ltd. All rights reserved.

  • 63. Gubanski, S. M.
    et al.
    Dernfalk, A.
    Wallström, Stina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Performance and diagnostics of biologically contaminated insulators2007Inngår i: ICPADM 2006: Proceedings of the 8th International Conference on Properties and Applications of Dielectric Materials, IEEE , 2007, s. 23-30Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biological growth has been observed on insulators installed all over the world. However, so far, its impact on insulator performance is not well known. This paper summarizes a majority of the work published in the field. Based on the gathered experiences, it can be concluded that microbiological growth is unlikely to cause severe degradation of the rubber housings of non-ceramic insulators. Furthermore, it seems that the impact of growth on the insulator performance is rather low. Techniques available for detection and characterisation of growth on insulators are also described and discusses. Among those, laser-induced fluorescence (LIF) spectroscopy has been found to give good results in remote detection of micro-organisms.

  • 64. Gubanski, S. M.
    et al.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Fernando, M. A. R. M.
    Performance of biologically contaminated high voltage insulators2006Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biological growth has been observed on insulators installed all over the world. However, so far, its impact on insulator performance is not well known. This paper summarizes the work published in the field. Based on the gathered experiences, it can be concluded that microbiological growth is unlikely to cause severe degradation of the rubber housings of non-ceramic insulators. Furthermore, it seems that the impact of growth on the insulator performance is rather low. Techniques available for detection and characterisation of growth on insulators are also described and discusses. Among those, laser-induced fluorescence (LIF) spectroscopy has been found to give good results in remote detection of micro-organisms.

  • 65. Gustavsson, T. G.
    et al.
    Gubanski, S. M.
    Hillborg, H.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Aging of silicone rubber under ac or dc voltages in a coastal environment2001Inngår i: IEEE transactions on dielectrics and electrical insulation, ISSN 1070-9878, E-ISSN 1558-4135, Vol. 8, nr 6, s. 1029-1039Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Material samples of silicone rubber with known differences in their composition, i.e. different filler content and extra silicone oil added, have been aged at the Anneberg field station on the west coast of Sweden. ac or dc voltage supplied to cylindrical samples at stress levels of 50 or 100 V/mm. The work includes laboratory examination of material changes together with on-site, visual observations and leakage current measurements. Material samplings for the laboratory tests were made after 18 months of electrical aging, which went on for one more year in order to gather further information on the long-term electrical performance of the material. The dominant aging factor was the level of the applied stress, independent of ac or dc voltage. The dc stressed samples showed a higher leakage current and exhibited larger surface degradation compared with samples exposed to ac voltage. The material parameter, an addition of extra silicone oil, initially lead to an increase in adhesion of pollutants, whereas the overall performance was improved by the higher suppression of the leakage current related to oligomer diffusion. Samples with lower level of alumina trihydrate (ATH) exhibited a delayed onset of degradation, but once damaged they degraded more rapidly than the specimens with a higher ATH content. Infrared spectroscopy showed that the ATH was completely consumed at the eroded surface regions. The aging of the surfaces was further assessed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The low molar mass siloxanes present in the pollution layer were extracted and analyzed by size exclusion chromatography and gas chromatography-mass spectroscopy. The results indicated that the main degradation factor was thermal depolymerization activated by electrical discharges. Oxidative crosslinking of the silicone rubber, usually attributed to surface close corona discharges, appeared to have played a minor role.

  • 66. Haider, N.
    et al.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Kinetics of migration of antioxidants from polyolefins in natural environments as a basis for bioconversion studies2000Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 1, nr 3, s. 481-487Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Plastics ending up in soil or landfill environment will eventually be degraded. At the same time a slow migration of additives from the plastics will occur. The additives and the degradation products of these and the polymer are potential compounds for bioconversion. To predict the rate of the migration of antioxidants from polyolefins, a medium-density polyethylene film MDPE containing two commercial antioxidants, Irganox 1010 and Irgafos 168, was exposed to simulated landfill environments, viz. aqueous media at pH 5 and 7, with temperatures of 25, 50, 80, and 105 degreesC and solid-to-liquid ratios of 1:5. The migration process of the antioxidants was studied by an ultrasonic extraction technique using chloroform as extraction solvent to recover the nonmigrated antioxidants from the polymeric matrix, followed by quantitative analysis of the extracted antioxidants by high performance liquid chromatography (HPLC) with acetonitrile as the mobile phase and a wavelength of 280 nm. It was found that the release of both Irganox 1010 and Irgafos 168 increases at higher temperature, longer time, and lower pH. Moreover, the migration of Irgafos 168 proceeds faster than that of Irganox 1010 at lower temperatures while at higher temperatures the opposite behavior was observed. No degradation of the polymeric matrix was detected under the testing time. Migration processes included diffusion of the antioxidants within the polymer and their desorption from the surface of the polymer into the boundary layers of leachate. In general, the kinetic of the migration process was well described by first-order equations while an Arrhenius-type relationship was applicable for the temperature dependence of the constants. The general constants calculated for the migration processes were applied to the prediction of the time required for complete release of the antioxidants under different landfill conditions.

  • 67. Haider, N.
    et al.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Loss and transformation products of the aromatic antioxidants in MDPE film under long-term exposure to biotic and abiotic conditions2002Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 85, nr 5, s. 974-988Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The loss of a primary phenolic antioxidant Irganox 1010 and of a secondary phosphite antioxidant Irgafos 168 from a medium density polyethylene film (MDPE) was investigated after exposure of the film for 4 years to different environments such as aqueous media at pH5 and 7, open air, and compost, with an exposure of exposition of 25degreesC. An ultrasonic extraction technique using chloroform as extraction solvent was applied to recover the residual antioxidants from the polymeric matrix, and this was followed by High-Performance Liquid Chromatography (HPLC) with acetonitrile as mobile phase and a quantitative analysis at a wavelength of 280 run of the extracted antioxidants. The amount of antioxidant lost varied remarkably depending on the testing medium. The fastest loss of antioxidant was found on exposure to open air and sunlight while the slowest loss was observed in compost. Thermo-analytical measurements were made to characterize the residual thermo-oxidative stability of MDPE film in terms of oxidation temperature and oxidation induction time, to provide a greater insight into the underlying mechanisms of ageing in the different environments. Analysis by Gas chromatography-Mass Spectrometry (GC-MS) revealed that degradation of the polymeric matrix resulted in the formation of hydrocarbons and oxygen-containing compounds such as alcohols, carboxylic acids, aldehydes, and esters. The transformation products of the antioxidants formed as result of processing or exposure to the tested media were also identified. The transformation of the phenoxy radical of the Irganox 1010 produced the ester, acid, dealkylated cinnamate, and quinone products, whereas Irgafos 168 yielded oxidation products and the phenolic hydrolysis byproduct 2,4-ditert-butylphenol.

  • 68. Haider, N.
    et al.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Loss of Chimassorb 944 from LDPE and identification of additive degradation products after exposure to water, air and compost2001Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 74, nr 1, s. 103-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A low-density polyethylene (LDPE) film containing a hindered amine light stabiliser (Chimassorb 944) was exposed to a composting mixture, chemical hydrolysis at pH 5 and pH 7 and air, in all cases at room temperature and for a period of 4 years. The structural changes of the LDPE film were investigated by differential scanning calorimetry (DSC) and size exclusion chromatography with viscosity detection (SEC-viscosity) while degradation products of LDPE and Chimassorb 944 were identified by gas chromatography-mass spectrometry (GC-MS). Determination of the amount of remaining stabiliser was performed using an ultrasonic extraction technique followed by LN spectroscopy analysis (250 nm, absorption of 1,3,5-triazine group). The ultrasonic extraction of Chimassorb 944 was carried out at 60 degreesC for a period of 1 h, using chloroform as extracting solvent. Loss of the stabiliser accompanied by structural changes of the polymeric matrix occurred during exposition time and was strongly influenced by exposure conditions. Thus, the fastest loss of the stabiliser was found on exposition to chemical hydrolysis at both pH while the slowest loss was observed during ageing in compost. Different products formed from Chimassorb 944 were found in all the tested environments as a result both of degradation of the stabiliser to smaller fragments and of reactions between these fragments and other additives present in LDPE. Thus, (Z)-9-octadecenamide was found in both unexposed and all the tested samples and was formed already during processing. 2,2,6,6-Tetramethyl-4-aminopiperidine was found in air and compost aged samples while 2,4-di-t-butyl-6-nitro-phenol was found in the samples exposed to air and water environments and [2-cyclohexene-1-dione, 3,5-dimethyl, O-methyloxime] were found exclusively in the samples aged in water at pH 5.

  • 69.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Polymerteknologi.
    Migration and emission of plasticizer and its degradation products during thermal aging of nitrite rubber2003Inngår i: IJPAC. International journal of polymer analysis and characterization, ISSN 1023-666X, E-ISSN 1563-5341, Vol. 8, nr 4, s. 279-293Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The behavior of nitrile rubber during long-term thermal aging was evaluated by following the migration of low-molecular-weight additives and additive degradation products from the material. Headspace-GC-MS analysis showed that at 60degreesC the number of low-molecular-weight compounds released was rather low, but a significant increase in the number and amount of products was observed when the temperature was raised from 60degrees to 80degreesC, e.g., several degradation products of tris(2-butoxyethyl)phosphate plasticizer including 2-butoxyethanol and 1-butanol were identified. Oxidation of the plasticizer was also seen in the FTIR spectra. The color of the material changed from light brown to almost black during the aging.

  • 70.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Influence of low molecular weight lactic acid derivatives on degradability of polylactide2000Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 76, nr 2, s. 228-239Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The presence of low molecular weight lactic acid derivatives in films enhanced the degradability of polylactide in a biotic medium. Two different biotic and abiotic series were investigated. The films used for the first abiotic and biotic series (a-l and b-1 films) initially contained some lactic acid and lactoyl lactic acid, while the films used for the second abiotic and biotic series (a-2 and b-2 films) did not originally contain them. The b-1 films decreased in molecular weight during 3 weeks in the biotic medium, while no molecular weight decrease was seen in the a-1 films aged in a corresponding abiotic mineral medium. The molecular weight for the a-2 and b-2 films without lactic and lactoyl lactic acid remained almost constant. Scanning electron microscopy micro-graphs showed a larger amount of bacteria and fungi growing on the surface of b-1 films compared to b-2 films; thus, the presence of easily assimilated lactic acid and lactoyl lactic acid in the films improved the initial growth of microorganisms on the film surfaces. Gas chromatography and mass spectrometry analysis showed that lactic acid and lactoyl lactic acid were rapidly assimilated from the films aged in a biotic medium. New degradation products (e.g., ethyl ester of lactoyl lactic acid, acetic acid, and propanoic acid) were formed during aging in a biotic medium. Acetic acid and propanoic acid were formed as intermediate degradation products during the initial stages, but they were no longer detected after prolonged aging. The concentration of the ethyl ester of lactoyl lactic acid increased with aging time.

  • 71.
    Hakkarainen, Minna
    et al.
    KTH, Tidigare Institutioner, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner, Polymerteknologi.
    Rapid (bio)degradation of polylactide by mixed culture of compost microorganisms - low molecular weight products and matrix changes2000Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 41, nr 7, s. 2331-2338Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly(L-lactide) (PLLA) was rapidly (bio)degraded by a mixed culture of compost microorganisms. After 5 weeks in biotic environment, the films had fragmented to fine powder, while the films in corresponding abiotic medium still looked intact. Analysis of the low molecular weight products by GC-MS showed that microorganisms rapidly assimilated lactic acid and lactoyl lactic acid from the films. At the same time, a new degradation product, ethyl ester of lactoyl lactic acid was formed in the biotic environment. This product cannot be formed by abiotic hydrolysis and it was not detected in the abiotic medium. The degradation of the PLLA matrix was monitored by differential scanning calorimetry (DSC), size exclusion chromatography (SEC) and scanning electron microscopy (SEM). A rapid molecular weight decrease and increasing polydispersity was observed in the biotic environment. In the abiotic environment only a slight molecular weight decrease was seen and the polydispersity started decreasing towards 2.0. This indicates different degradation mechanisms, i.e. preferred degradation near the chain ends in the biotic environment and a random hydrolysis of the ester bonds in the abiotic environment. SEM micrographs showed the formation of patterns and cracks on the surface of the films aged in biotic medium, while the surface of the sterile films remained smooth. The SEM micrographs showed a large number of bacteria and mycelium of fungi growing on the surface of the biotically aged films.

  • 72. Hillborg, H.
    et al.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Characterisation of low molar mass siloxanes extracted from crosslinked polydimethylsiloxanes exposed to corona discharges2001Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 42, nr 21, s. 8883-8889Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Crosslinked polydimethylsiloxanes were exposed to corona discharges in dry air at normal pressure. Short-time solvent extraction and subsequent analysis of the extractables, by gas chromatography, mass spectrometry and size exclusion chromatography showed that, oligomers consisting mainly of cyclics with 4-9 repeating units were formed during corona exposure. The size distribution of the oligomers was independent of the crosslink density and corona exposure time. The amount of oligomers located at the surface increased, with increasing storage time, after the corona exposure in qualitative agreement with the ongoing hydrophobic recovery process. Longer extractions penetrated deeper into the samples, and, in addition to the cyclic oligomers, higher molar mass species (similar to 50,000 g mol(-1) for unexposed samples) were detected. Samples exposed to corona, treated in this way, showed a broadening of the high molar mass peak towards lower molar masses.

  • 73. Jansson, S. E. A.
    et al.
    Gallet, G.
    Hefti, T.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Packaging materials for fermented milk Part 2: Solute-induced changes and effects of material polarity and thickness on food quality2002Inngår i: Packaging technology & science, ISSN 0894-3214, E-ISSN 1099-1522, Vol. 15, nr 6, s. 287-300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work is a continuation of the application of a developed methodology for the selection of packaging material for a specific food product, in this case the 'demanding' food product. fermented milk. The effects of different packaging material parameters on the quality of fermented milk were studied. Food quality after storage was determined as a function of material polarity and pouch thickness by storing the liquid in pouches of different materials. The material polarity was varied by using laminates with polyethylene, poly(ethylene-co-vinyl alcohol) with two different ethylene contents and an aliphatic polyketone. The effects of pouch thickness were studied using high-density polyethylene films of different thicknesses between 25 mum and 200 mum. The interactions between the milk product and the pouch material were analysed by oxygen and water permeability, gas chromatography-mass spectrometry and tensile testing. The CO2 and O-2 contents in the headspace of the pouches were determined. The food quality was determined by measuring whey syneresis and the contents of Bifidobacteria, Enterobacteriaceae, yeast and mould. A trained taste panel determined the sensory properties. The content of CO2, and consequently the sparkling taste, increased with increasing polarity and/or pouch thickness. The CO2 content was affected more easily by changes in material polarity than by changes in pouch thickness. The increase in whey syneresis and the decrease in Bifidobacteria content with time were independent Of material polarity and pouch thickness. The contents Of Enterobacteriaceae, yeast and mould in the liquid were always below existing limits for foodstuffs. A newly developed method was used by which the CO2 and 02 permeabilities of the pouch/packaging could be estimated, using the kinetics of the gas composition in the pouch headspace. Permeability values, as estimated by the method, revealed that the CO2 production and the O-2 consumption rates of the fermented milk were dependent on the CO2 and O-2 headspace concentrations. An increase in permeability, determined by conventional methods, suggested that both the non-polar and the polar polymers were plasticized by fermented milk. The plasticization was, however, modest and undetectable when the polyethylene tensile test data were analysed.

  • 74.
    Kaali, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Markstrom, Agneta
    Aune, Ragnhild E.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Czel, Gyorgy
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Degradation of Biomedical Polydimethylsiloxanes During Exposure to In Vivo Biofilm Environment Monitored by FE-SEM, ATR-FTIR, and MALDI-TOF MS2010Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 115, nr 2, s. 802-810Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Polymers used for biomedical purposes in medical devices are usually requested to be inert to degradation. This article describes that slow irreversible changes were observed in silicone surfaces exposed to in vivo biofilms even if silicone, in general, is supposed to have excellent long-term properties. Tracheostomy tubes made of silicone rubber were exposed to in vivo biofilm environments in clinical tests for periods of 7, 3, and 6 months. The chemical degradation was monitored by MALDI-TOF MS, ATR-FTI.R, and FE-SEM. In addition, the physical changes were monitored by contact angle and hardness measurements. Cyclic polydimethylsiloxane (PDMS) was detected on the surfaces of new (unaged) silicones. On the surfaces of the in vivo samples new compounds, presumably linear methyl-hydroxyl-terminated PDMS, were detected in addition to cyclic PDMS. These compounds may be formed as a result of the hydrolysis of linear dimethyl terminated PDMS, which is also present in the silicone rubber. ATR-FTIR spectroscopy confirmed that hydrolysis had indeed occurred during the in vivo exposure, since Si-OH groups were detected. Furthermore, significant changes in the topography were detected by FE-SEM, indicating the initiation of degradation. No significant changes in the contact angle of the in vivo used samples were observed, but this information may be shielded by the fact that biofilm may remain on the surface, despite the thorough cleaning before the analysis. It is also possible that the surface hydrophobicity was recovered by the diffusion of linear low-molecular-weight compounds from the bulk.

  • 75.
    Kaali, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Pérez-Madrignal, Maria M.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Aune, Ragnhild E.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Czel, Gyorgy
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    The influence of Ag(+), Zn(2+) and Cu(2+) exchanged zeolite on antimicrobial and long term in vitro stability of medical grade polyether polyurethane2011Inngår i: Express Polymer letters, ISSN 1788-618X, Vol. 5, nr 12, s. 1028-1040Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study aims to investigate the limitations and applicability of different ion exchanged zeolites as antimicrobial additive in thermoplastic polyether type polyurethanes. These composites were designed to improve the health quality of hospitalized patients by expressing both biocompatibility and relevant antimicrobial activity. The zeolites were exchanged with silver, copper and zinc ions and single, binary and ternary ion-exchanged zeolite-polyurethane composites were prepared. The antimicrobial activity and the resistance of the composites against the human environment play vital role in the applicability of the materials as a medical device therefore these properties were investigated. The antimicrobial test were performed on Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa and Candida tropicalis. The tests showed that the efficiency of the silver ions is superior to the other single ionic systems. Besides, the binary and ternary ion-exchanged samples had similar antimicrobial efficiency regardless the type of the ions in the zeolite. The biocompatibility tests were carried out in-vitro in artificial body fluids for a period of 12 weeks. As a result of the in-vitro test, degradation of the composites were observed and the structural changes of the materials were detected and described by Scanning Electron Microscopy, Contact Angle measurements and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy.

  • 76.
    Kaali, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Aune, Ragnhild E.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Czel, Gyoergy
    Department of Polymer Engineering, University of Miskolc.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Antimicrobial properties of Ag+ loaded zeolite polyester polyurethane and silicone rubber and long-term properties after exposure to in-vitro ageing2010Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 95, nr 9, s. 1456-1465Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In biomedical applications, tubes (e.g. catheters etc.) are commonly produced from polyurethane (PU) and silicone rubber which are known to be biocompatible materials. Several studies have shown that tubes, which are connected to the body (invasive) (especially urinary, tracheotomy and central venous catheters) are associated with infections. The present study reports the development of a new method aiming at obtaining antibacterial properties for PU and silicone rubber by mixing respective material with a natural antibacterial agent (Ag+ loaded zeolite) in different weight fractions. The influence of the zeolite content on the antimicrobial properties were analysed by exposure to bacteria (ISO 22196) and mixtures of fungi (ISO 846). The materials were also subject to artificial body fluids (Artificial Lysosomal Fluid (ALF) and Gamble's solution) for periods up to three months and the subsequent changes in the chemical properties after in-vitro exposure were determined by Matrix Assisted Laser Deposition/Ionization Time Of Flight Mass Spectrometry (MALDI-TOF MS) and Attenuated Total Reflection Fourier Transform Infra Red spectroscopy (ATR-FTIR). It was established that the antimicrobial effect of the materials increased with the increase of the zeolite content. The wettability of the materials was found to decrease significantly during the in-vitro exposure, but this could not be correlated to the zeolite content. In the PU samples, the formation of free carbonyl and -OH groups was observed, which corresponds to oxidative degradation. In case of the silicone rubber the ratio of cyclic PDMS to linear PDMS (H, CH3 and dimethyl terminated) decreased, which indicates a change in the concentration of the compounds. The formation and increase of the O-H bond during the exposure was also confirmed by the infrared spectra of the material which corresponds to hydrolysis of the silicone rubber.

  • 77.
    Kaali, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Aune, Ragnhild E.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Czel, Gyorgy
    Modelling the ion distribution in single, binary and ternary ion exchanged Azeolite2011Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093Artikkel i tidsskrift (Annet vitenskapelig)
  • 78.
    Kaali, Peter
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Prevention of Biofilm Associated Infections and Degradation of Polymeric Materials Used in Biomedical Applications2011Inngår i: Biomedical Engineering, Trends in Materials Science / [ed] Anthony N. Laskovski, InTech , 2011Kapittel i bok, del av antologi (Fagfellevurdert)
  • 79.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner, Fiber- och polymerteknologi.
    Recycled polyolefins. Material properties and means for quality determination2004Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 169, s. 201-229Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Recycling of polymers has come to be a necessary part of the development of a sustainable society. Recycling of low price bulk polymers, to which group the polyolefins belong, is seen by many as a waste of time and resources when they simply may be energy recovered. Several life-cycle assessments (LCA) have, however, proven that it is also valuable to material recycle bulk polymers such as polyolefins. In many instances, polyolefins are inplant recycled and used again in similar products, but they may also be separated and sorted from municipal solid waste. This paper will discuss recycled polyolefins, in particular their change in material properties and how to characterise these properties and show that these analyses are a basis for quality determination. In fact, an important vehicle for the success of recycled polymeric materials is to use a quality concept. Accurate determination of a series of polymeric properties will be the only way recycled polymeric materials can compete with virgin ones. Analytical methods useful in the quality concept are presented and discussed. In particular, three parameters are important for quality measurements. These are degree of degradation, polymer composition and presence of low molecular weight compounds (degradation products of polymer matrix and additives, initiator/catalysts, solvents, use-related e.g. fragrance or flavour etc.). For the future it is important to give recycled polymeric materials status as resources besides the fossil and renewable ones.

  • 80.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    EU:s utsläppshandel otillräckligt för flyget.2018Inngår i: Dagens NyheterArtikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 81.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Bengtsson, Stefan
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    Hörstedt, Fredrik
    Höjer, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Strategiska hållbarhetsstudier.
    Hyfs och kunskap krävs i debatten om flyg och klimat.2018Inngår i: Dagens NyheterArtikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 82.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Finnveden, Göran
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Hållbarhet, utvärdering och styrning.
    KTH måste göra mer för klimatomställningen.2018Inngår i: Dagens NyheterArtikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 83.
    Karlsson, Sigbritt
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Momcilovic, Dane
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Enebro, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Cellulose and cellulose derivatives in biomedical materials: Tools to propose the chemical structure by mass spectrometry2009Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 237Artikkel i tidsskrift (Annet vitenskapelig)
  • 84. Khabbaz, F.
    et al.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Albertsson, Ann-Christine
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Py-GC/MS an effective technique to characterizing of degradation mechanism of poly (L-lactide) in the different environment2000Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 78, nr 13, s. 2369-2378Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The biotic and abiotic degradation of poly (L-lactide) (PLLA) has been studied with pyrolysis gas chromatography mass spectrometry (Py-GC-MS). A mixed culture of compost micro-organisms was used as the biotic medium. Size-exclusion chromatography (SEC), gas chromatography-mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were utilized to monitor the degradation and degradation mechanism. Differences in pH, molecular weight, surface structure, and degradation mechanisms were noted between sample aged in biotic and abiotic medium. Using fractionated Py-GC-MS at 400 and 500 degreesC, acetaldehyde, acrylic acid, lactoyl acrylic acid, two lactide isomers, and cyclic oligomers up to the pentamer were identified as thermal decomposition products of PLA as well as some other not completely identified products. The ratio of meso-lactide to L-lactide was lower in the sample aged in the biotic media than the abiotic media. This is a result of the preference of the micro-organisms for L-form of lactic acid and lactoyl lactic acid rather than the D-form that in turn influences the formation and the amounts of meso and D,L-lactide during the pyrolysis. Based on SEM micrographs, it was shown that degradation in the biotic medium proceeded mainly via a surface erosion mechanism, whereas bulk erosion was the predominant degradation mechanism in the abiotic medium. The SEC and Py-GC-MS data indicate that degradation was faster in the biotic than in the abiotic sample.

  • 85.
    Kittikorn, Thorsak
    et al.
    Prince Songkla Univ, Dept Mat Sci & Technol, Fac Sci, Hat Yai 90112, Thailand..
    Malakul, Raminatun
    Prince Songkla Univ, Dept Microbiol, Fac Sci, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Enhancement of mechanical, thermal and antibacterial properties of sisal/polyhydroxybutyrate-co-valerate biodegradable composite2018Inngår i: JOURNAL OF METALS MATERIALS AND MINERALS, ISSN 0857-6149, Vol. 28, nr 1, s. 52-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lignocellulosic biocomposite is a promising biodegradable materials, though improvement of the interfacial adhesion between cellulose fibre and polymer matrix is still challenged. Therefore, this work investigated the effect of propionylation of sisal reinforced fibre in the sisal/polyhydroxybutyrate-co-valerate (PHBV) biocomposite. Propionylation involved esterification substitution of propionic anhydride to hydroxyl group of sisal fibre, where ester group (COOR) of propionylated fibre was successfully observed by Fourier transform Infrared spectroscopy (FTIR). Then mechanical and thermal properties were evaluated and biodegradation characteristics were assessed. The tensile strength and modulus of propionylated sisal/PHBV biocomposite were greater than unmodified sisal/PHBV, which revealed better compatibility at the interface. In addition, propionate moieties of sisal fibre could induce crystalline formation of PHBV, as determined by an increase of crystalline phase. The higher decomposition temperature (Td) and activation energy (Ea) of 155 kJ.mol(-1), determined by thermal gravimetric analyser (TGA), were strong confirmation of good thermal resistance of the propionylated sisal biocomposite. The storage modulus, as characterized by dynamic mechanical thermal analyser (DMTA), also revealed the improvement of stiffness. Bacterial growth tests evaluated the inhibition of bacterial growth on the PHBV biocomposites. It was clear that propionylation of sisal fibre decreased colonization of Staphylococcus aureus (SA) and Escherichia coli (E.coli).

  • 86.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Chemical surface modification of empty fruit bunch oil palm fibre in PP biocomposites2009Konferansepaper (Annet vitenskapelig)
  • 87.
    Kittikorn, Thorsak
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Strömberg, Emma
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Ek, Monica
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Karlsson, Sigbritt
    Högskolan i Skövde. KTH Royal Institute of Technology, Stockholm, Sweden.
    Comparison of water uptake as function of surface modification of empty fruit bunch oil palm fibres in PP biocomposites2013Inngår i: BioResources, ISSN 1930-2126, Vol. 8, nr 2, s. 2998-3016Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Empty fruit bunch oil palm (EFBOP) fibres were surface modified by four different methods, propionylation, vinyltrimethoxy silanization, PPgMA dissolution modification, and PPgMA blending, and integrated into a polypropylene (PP) matrix. The designed biocomposites were subjected to an absorption process at different temperatures. Their water uptake behaviour was compared with the unmodified fibre biocomposites. An increased fibre content and temperature resulted in increased water uptake for all of the biocomposites. The biocomposites containing modified fibres showed a reduction in water uptake, rate of diffusion, sorption, and permeation in comparison with unmodified fibre composites. Comparing the 20 wt% fibre composites at ambient temperature, the performance in water absorption followed the sequence silanization < propionylation < PPgMA dissolution modification < PPgMA blending < no modification. Furthermore, the lowest water absorption was obtained from the silanized fibre/PP composite with 40% fibre content at ambient temperature. Dissolution or blending of PPgMA gave similar water uptake results. The reduction of diffusion, sorption, and permeation confirmed that the modification of fibres was potentially effective at resisting water penetration into the composites.

  • 88.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Comparison of Water Uptake as Function of Surface Modification of Empty Fruit Bunch Oil Palm Fibres in PP Biocomposites2013Inngår i: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 8, nr 2, s. 2998-3016Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Empty fruit bunch oil palm (EFBOP) fibres were surface modified by four different methods, propionylation, vinyltrimethoxy silanization, PPgMA dissolution modification, and PPgMA blending, and integrated into a polypropylene (PP) matrix. The designed biocomposites were subjected to an absorption process at different temperatures. Their water uptake behaviour was compared with the unmodified fibre biocomposites. An increased fibre content and temperature resulted in increased water uptake for all of the biocomposites. The biocomposites containing modified fibres showed a reduction in water uptake, rate of diffusion, sorption, and permeation in comparison with unmodified fibre composites. Comparing the 20 wt% fibre composites at ambient temperature, the performance in water absorption followed the sequence silanization < propionylation < PPgMA dissolution modification < PPgMA blending < no modification. Furthermore, the lowest water absorption was obtained from the silanized fibre/PP composite with 40% fibre content at ambient temperature. Dissolution or blending of PPgMA gave similar water uptake results. The reduction of diffusion, sorption, and permeation confirmed that the modification of fibres was potentially effective at resisting water penetration into the composites.

  • 89.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Effect of surface modifications on microbial growth and biodegradation in sisal/PLA biocomposites2013Manuskript (preprint) (Annet vitenskapelig)
  • 90.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Susceptibility to biodegradation by fungi for sisal/PLA and sisal/PHBV biocomposites2013Manuskript (preprint) (Annet vitenskapelig)
  • 91.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    The effect of surface modifications on the mechanical and thermal properties of empty fruit bunch oil palm fibre PP biocomposites2012Inngår i: Polymers from Renewable Resources, ISSN 2041-2479, Vol. 3, nr 3, s. 79-100Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to study the effect of chemical surface modifications on empty fruit bunch oil palm fibre/polypropylene composite properties. By FTIR spectra, propionylated fibre and PPgMA-modified fibre showed the presence of a carbonyl group of esters while vinyltrimethoxysilane-treated fibre showed a peak of silicate, confirming that the modifications were successful. PPgMAmodified fibre PP composite at fibre content 20% demonstrated the highest modulus of 0.71 GPa while the modulus of unmodified fibre PP composite was 0.56 GPa. By DSC analysis, PPgMA-modified fibre and vinyltrimethoxysilane-treated fibre PP composite at the same fibre content of 5% showed the highest crystallinity of 46% and 44% respectively whereas unmodified fibre PP composite showed a lower crystallinity of 38%. The DMTA analysis showed that after 60°C, the modified fibre PP composites exhibited a higher stiffness than pure polypropylene.

  • 92.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material. Skövde University.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    The mechanical properties of natural cellulosic fiber/biodegradable polymer biocomposites2011Inngår i: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC, 2011, s. 1330-1333Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this work was to investigate a methodology for the improvement of the mechanical properties of sustainable biodegradable biocomposites based on polylactide (PLA). Cellulosic fibre was incorporated as a reinforcing agent for improvement of the mechanical properties of the biocomposites. A coupling agent was synthesized and employed in order to enhance the interfacial adhesion of two components via a melt blending process. FT-IR spectra showed presences of specific functional groups of maleic anhydride on the backbone of the PLA after the grafting. The modulus of PLA was considerably raised after incorporation of the fibre. Furthermore, an addition of a coupling agent in PLA biocomposites was also able to remarkably increase the stiffness of the material.

  • 93.
    Kittikorn, Thorsak
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Träkemi och massateknologi.
    The mechanical properties of natural cellulosic fibre/biodegradable polymer biocomposites2011Inngår i: 16th International Symposium on Wood, Fiber and Pulping Chemistry - Proceedings, ISWFPC: Volume 2, 2011, s. 1330-1333Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Theaim of this work was to investigate a methodology fortheimprovement ofthemechanicalpropertiesof sustainablebiodegradablebiocompositesbased on polylactide (PLA).Cellulosicfibrewas incorporated as a reinforcing agent for improvement ofthemechanicalpropertiesofthebiocomposites. A coupling agent was synthesized and employed in order to enhancetheinterfacial adhesion of two components via a melt blending process. FT-IR spectra showed presences of specific functional groups of maleic anhydride onthebackbone ofthePLA afterthegrafting.Themodulus of PLA was considerably raised after incorporation ofthefibre. Furthermore, an addition of a coupling agent in PLAbiocompositeswas also able to remarkably increasethestiffness ofthematerial.

  • 94. Lindblad, M. S.
    et al.
    Liu, Y.
    Albertsson, A. C.
    Ranucci, E.
    Karlsson, Sigbritt
    KTH, Tidigare Institutioner                               , Polymerteknologi.
    Polymers from renewable resources2002Inngår i: Advances in Polymer Science, ISSN 0065-3195, E-ISSN 1436-5030, Vol. 157, s. 139-161Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    From the point of view of making novel polymers with inherent environment-favorable properties such as renewability and degradability, a series of interesting monomers are found in the metabolisms and cycles of nature. This review presents and discusses a number of aliphatic polyesters which show interesting applications as biomedical materials and degradable packages. Available from nature are amino acids, microbial metabolites from the conversion of glucose and other monosaccharides (e.g., acetic acid, acetone, 2,3-butanediol, butyric acid, isopropanol, propionic acid), lactic acid, ethanol and fatty acids. A series of biodegradable polymers with different properties and different potential industrial uses were made starting with succinic acid and/or 1,3-propanediol. There were two routes for making the polyester-based materials; the direct ring-opening polymerization of lactones (cyclic esters) synthesized from 1,3-propanediol, and the chain-extension of alpha,omega-dihydroxy-terminated oligomeric polyesters produced by thermal polycondensation of 1,3-propanediol and succinic acid (oligo(propylene succinate)s).

  • 95. Lugoye, M.
    et al.
    Ndazi, B. S.
    Tesha, J.
    Nyahumwa, C.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Characterising technical cashew nut shell liquid using Maldi-ToF MS2017Inngår i: Natural Products Journal, ISSN 2210-3155, Vol. 7, nr 4, s. 281-285Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Various techniques have been applied for detecting anacardic acid, cardanol, cardol, and 2-methylcardol and their degrees of unsaturation in a complex mixture of a highly corrosive cashew nut shell liquid found in the cashew (anacardium occidentale) nut shells. However, very little has been reported on the applicability of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry for the same. The aim of this paper is to report the application of this technique for identifying those components in technical cashew nut shell liquid obtained by a hot-roasting process. Methods: The cashew nut shell liquid analyte was diluted in acetone before adding a matrix of 2,5- dihydroxybenzoic acid, which contained acetone in a volumetric ratio of 1:2. This was followed by doping the analyte with either sodium or silver trifluoroacetate. Results: The mass spectra obtained by both sodium trifluoroacetate and silver trifluoroacetate dopants revealed existence of well-resolved peaks ascribed to cardanol and cardol in the analyte. It was further observed that the peaks corresponding to 2-methyl cardol and anacardic acid in the analyte could only be detected by using sodium trifluoroacetate dopant. The results have further revealed the possibility of the material to contain traces of other components between 0.3 and 23%. Peaks associated with those components may have been overlapped with peaks ascribed to the phenolic components. Conclusion: The results therefore suggest that this technique may be applicable for characterising the composition of technical cashew nut shell liquids when proper sample preparation is done and appropriate solvents, dopants and matrices are used.

  • 96.
    Luttropp, Conrad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Johansson, Jan
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinelement.
    Vilaplana, Francisco
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Design for material hygiene - An ecodesign strategy for improved recycling of polymers2010Inngår i: Proceedings of the 8th International Symposium on Tools and Methods of Competitive Engineering, TMCE 2010, 2010, s. 1223-1231Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recycling of polymers has come into focus lately. Many polymers carry a backpack of energy from manufacturing, which is lost in present recycling of e.g. automotives and small house hold appliances. This calls for higher efficiency in recycling. To take a step in this direction a literature study is made and an experiment at a recycling plant for refrigerators and freezers. A batch of 30m3 of electronic waste was collected and processed in a so-called Hurricane machine. The experiment showed that recycling of polymers can be made on higher levels of efficiency with the used machine, if complemented with sorting and some initial processing before shredding. In order to improve polymer recycling a set of process steps must be designed in order to get secondary polymer fractions that can be used in products.

  • 97. Moliner, C.
    et al.
    Badia, J. D.
    Bosio, B.
    Arato, E.
    Kittikorn, T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi. e Department of Materials Science and Technology, Faculty of Science, Prince of Songkla University, Songkhla, Thailand .
    Strömberg, Emma
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Teruel-Juanes, R.
    Ek, Monica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ribes-Greus, A.
    Thermal and thermo-oxidative stability and kinetics of decomposition of PHBV/sisal composites2018Inngår i: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 205, nr 2, s. 226-237Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The decomposition behaviours of composites made of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and sisal were assessed in terms of thermal stability and decomposition kinetics, under inert and oxidative conditions, by means of multi-rate linear non-isothermal thermogravimetric experiments. A statistical design of experiments was applied to study the influence of the addition of sisal (0–10–20–30%wt), the presence coupling agent (Yes/No) and the applied conditions of work (inert or oxidative). An improvement of the thermal and thermo-oxidative stability of PHBV with the addition of sisal was observed for all cases. An accurate methodology based on iso-conversional methods was applied to simulate the potential of thermal recovery technologies, such as pyrolysis and controlled combustion, to use these biocomposites after the end of their service life. The mathematical descriptions of both thermo-chemical reactions were helpful in the evaluation of the eventual optimal operational conditions to carry out a suitable energetic valorisation. A minimum of 240°C and 137 kJ/mol of activation energy in inert conditions and 236°C and 118 kJ/mol in oxidative conditions ensured the feasibility of the reactions regardless the composition of the PHBV/sisal biocomposites, which may ease the operability of further energy valorisation with the aim to turn biowaste into new fuels.

  • 98.
    Moliner, C.
    et al.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy.;Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Badia, J. D.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain.;Univ Valencia, Escola Tecn Super Engn, Dept Engn Quim, Av Univ S-N, E-46100 Burjassot, Spain..
    Bosio, B.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Arato, E.
    Univ Genoa, DICCA, Via Opera Pia 15, I-16145 Genoa, Italy..
    Teruel-Juanes, R.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Kittikorn, Thorsak
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi. Prince Songkla Univ, Fac Sci, Dept Mat Sci & Technol, Hat Yai 90112, Thailand..
    Strömberg, Emma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ek, Monica
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi.
    Ribes-Greus, A.
    Univ Politecn Valencia, ITM, Camino Vera S-N, E-46022 Valencia, Spain..
    Thermal kinetics for the energy valorisation of polylactide/sisal biocomposites2018Inngår i: Thermochimica Acta, ISSN 0040-6031, E-ISSN 1872-762X, Vol. 670, s. 169-177Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The thermal stability and decomposition kinetics of PLA/sisal biocomposites was discussed to evaluate the suitability of their use in energy recovery processes such as pyrolysis and combustion. The influence of the addition of sisal up to 30%wt, the presence of coupling agent, and the atmosphere of operation, i.e. inert or oxidative was discussed by means of multi-rate linear non-isothermal thermogravimetric experiments. All biocomposites showed a mean high heating value of 15 MJ/kg indicating their suitability for energy recovery processes. The thermal requirements of PLA/sisal decomposition were assessed in terms of onset decomposition temperature and apparent activation energy. A minimum of 240 degrees C and 174 kJ mol(-1) in inert environment and 225 degrees C and 190 kJ mol(-1) in oxidative environment ensured the feasibility of the reactions regardless the composition of the PLA/sisal biocomposites. The atmosphere of work lead to a greater amount of residue in case of pyrolysis reactions that would need further treatment whereas an oxidative atmosphere resulted in nearly zero final waste stream. The similar kinetics obtained for all samples regardless the amount of sisal or use of coupling agent eases the operability of energy facilities aimed of turning these biowastes into new fuels.

  • 99. Momcilovic, D.
    et al.
    Aune, Ragnhild E.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Material Property Changes vs. Release of Phthalates from In-vitro and In-vivo Aged Biomaterials Made of PVC2008Konferansepaper (Fagfellevurdert)
  • 100. Moore, Alastair J.
    et al.
    Cetti, Edward
    Haj-Yahia, Saleem
    Carby, Martin
    Bjoerling, Gunilla
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Shah, Pallav
    Goldstraw, Peter
    Moxham, John
    Jordan, Simon
    Polkey, Michael I.
    Unilateral Extrapulmonary Airway Bypass in Advanced Emphysema2010Inngår i: Annals of Thoracic Surgery, ISSN 0003-4975, E-ISSN 1552-6259, Vol. 89, nr 3, s. 899-906E2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background. Gas trapping in emphysema results in resting and dynamic hyperinflation. We tested the hypothesis that a direct connection between the lung parenchyma and the atmosphere could increase expiratory flow and thereby potentially improve dyspnea through the relief of gas trapping. Methods. Ex vivo we studied 7 emphysematous lungs and 3 fibrotic lungs (as controls) and measured expiratory flow before and after airway bypass insertion during a forced maneuver in an artificial thorax. Pilot studies were conducted in vivo in 6 patients with advanced emphysema using a size 9 endotracheal tube as a bypass surgically placed through the chest wall into the upper lobe. Results. In the ex vivo emphysematous lungs the volume expelled during a forced expiratory maneuver increased from 169 to 235 mL (p < 0.05). In the in vivo group 4 patients retained the bypass tube for 3 months or more; total lung capacity was reduced, and the forced expiratory volume in 1 second increased by 23% (mean percent predicted at baseline versus 3 months, 24.4% versus 29.5%). Conclusions. An extrapulmonary airway bypass increases expiratory flow in emphysema. This may be a useful approach in hyperinflated patients with homogeneous emphysema. (Ann Thorac Surg 2010;89:899-906)

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