Endre søk
Begrens søket
1234567 1 - 50 of 775
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Abdi, Sofia
    KTH, Skolan för kemivetenskap (CHE).
    Preparation and process optimization of encapsulating cellulose microspheres2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter.

    Due to the their small size and round shape, microspheres show many advantages in various

    applications such as pharmaceuticals, composites and coatings. The microspheres can be

    customized to fit a specific application and are manufactured in various forms such as solid,

    hollow and encapsulating.

    Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent

    evaporation technique. The purpose of this study was to further investigate the

    possibility of producing encapsulating microspheres with a size range of 10-50 μm that will

    have a high encapsulation. A second purpose of this study was optimizing the emulsifier

    system for the preparation of these spheres. This has been accomplished by varying several

    process parameters such as type of emulsifiers and solvents to study the effect on morphology

    and encapsulation efficiency. The analyses of the spheres were performed with optical

    microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM).

    The emulsifier type and concentration affected the encapsulation and size distribution but had

    no direct effect on the internal and external structure, which was multi-cellular and porous,

    respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v-

    % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used

    to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2)

    and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and

    high number average molecular weight. The solvent also had an effect on the internal

    structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

  • 2. Adamus, Grazyna
    et al.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Höglund, Anders
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Kowalczuk, Marek
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters2009Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, nr 6, 1540-1546 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.

  • 3.
    Akan, Rabia
    KTH, Skolan för kemivetenskap (CHE).
    Oorganiska-organiska nanopartikelbaserade supramolekylära strukturer för biomedicinska applikationer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The possibility to create a multifunctional nanoparticle system via supramolecular chemistry approach with ability to simultaneously target, deliver and diagnose was investigated. Superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation method and surface modified with the cyclic oligosaccharide carboxymethyl-β-cyclodextrin by three different routes. The different routes involved one, two or three reaction steps in order to reach to the final oligosaccharide functionalized nanoparticles. Esterification was performed using the intrinsic hydroxyl functionality of the nanoparticle surfaces or amine functionality was introduced prior to amidization. Further, a polymeric coating was created by incorporation of folic acid functionalized Pluronic® L-35 into carboxymethyl-β-cyclodextrin. The resulting nanoparticle based supramolecular systems were characterized by TEM, TGA, FT-IR, DLS and zeta potential techniques.

     

    The colloidal stabilities of the supramolecular nanoparticle systems were investigated in phosphate buffered saline with pH 7.4 representing body conditions. It was found that a three-step functionalization of iron oxide nanoparticles with citric acid, hexamethylenediamine and finally carboxymethyl-β-cyclodextrin resulted in the most stable ferrofluids. The average size of the resulting carboxymethyl-β-cyclodextrin functionalized nanoparticles was 25 nm prior to, and 50 nm after inclusion of folic acid functionalized Pluronic. The amount of grafted carboxymethyl-β-cyclodextrin on the nanoparticles surfaces was 25 weight %. Thus, the resulting stable ferrofluid creates an efficient platform with potential of multiple uses in biomedicine. This nanoparticle based supramolecular system combines the properties of magnetic targeting and MRI contrast enhancement due to the superparamagnetic iron oxide nanoparticle core, drug delivery of hydrophobic drugs due to the polymer capsule and selective targeting towards tumour cells due to the folic acid.

  • 4.
    Akhlaghi, Shahin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Degradation of acrylonitrile butadiene rubber and fluoroelastomers in rapeseed biodiesel and hydrogenated vegetable oil2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Biodiesel and hydrotreated vegetable oil (HVO) are currently viewed by the transportation sector as the most viable alternative fuels to replace petroleum-based fuels. The use of biodiesel has, however, been limited by the deteriorative effect of biodiesel on rubber parts in automobile fuel systems. This work therefore aimed at investigating the degradation of acrylonitrile butadiene rubber (NBR) and fluoroelastomers (FKM) on exposure to biodiesel and HVO at different temperatures and oxygen concentrations in an automated ageing equipment and a high-pressure autoclave. The oxidation of biodiesel at 80 °C was promoted by an increase in the oxygen partial pressure, resulting in the formation of larger amounts of hydroperoxides and acids in the fuel. The fatty acid methyl esters of the biodiesel oxidized less at 150 °C on autoclave aging, because the termination reactions between alkyl and alkylperoxyl radicals dominated over the initiation reactions. HVO consists of saturated hydrocarbons, and remained intact during the exposure. The NBR absorbed a large amount of biodiesel due to fuel-driven internal cavitation in the rubber, and the uptake increased with increasing oxygen partial pressure due to the increase in concentration of oxidation products of the biodiesel. The absence of a tan δ peak (dynamical mechanical measurements) of the bound rubber and the appearance of carbon black particles devoid of rubber suggested that the cavitation was caused by the detachment of bound rubber from particle surfaces. A significant decrease in the strain-at-break and in the Payne-effect amplitude of NBR exposed to biodiesel was explained as being due to the damage caused by biodiesel to the rubber-carbon-black network. During the high-temperature autoclave ageing, the NBR swelled less in biodiesel, and showed a small decrease in the strain-at-break due to the cleavage of rubber chains. The degradation of NBR in the absence of carbon black was due only to biodiesel-promoted oxidative crosslinking. The zinc cations released by the dissolution of zinc oxide particles in biodiesel promoted reduction reactions in the acrylonitrile part of the NBR. Heat-treated star-shaped ZnO particles dissolved more slowly in biodiesel than the commercial ZnO nanoparticles due to the elimination of inter-particle porosity by heat treatment. The fuel sorption was hindered in HVO-exposed NBR by the steric constraints of the bulky HVO molecules. The extensibility of NBR decreased only slightly after exposure to HVO, due to the migration of plasticizer from the rubber. The bisphenol-cured FKM co- and terpolymer swelled more than the peroxide-cured GFLT-type FKM in biodiesel due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. The FKM rubbers absorbed biodiesel faster, and to a greater extent, with increasing oxygen concentration. It is suggested that the extensive biodiesel uptake and the decrease in the strain-at-break and Young’s modulus of the FKM terpolymer was due to dehydrofluorination of the rubber by the coordination complexes of biodiesel and magnesium oxide and calcium hydroxide particles. An increase in the CH2-concentration of the extracted FKM rubbers suggested that biodiesel was grafted onto the FKM at the unsaturated sites resulting from dehydrofluorination.

  • 5.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Amir Masoud, Pourrahimi
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ulf W., Gedde
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Degradation of fluoroelastomers in rapeseed biodiesel at different oxygen concentrations2017Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 136, 10-19 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The degradation of fluoroelastomers (FKM) based on different monomers, additives and curing systems was studied after exposure to rapeseed biodiesel at 100 °C and different oxygen partial pressures. The sorption of fuel in the carbon black-filled FKM terpolymer was promoted by the fuel-driven cavitation in the rubber. The bisphenol-cured rubbers swelled more in biodiesel than the peroxide-cured FKM, presumably due to the chain cleavage caused by the attack of biodiesel on the double bonds formed during the bisphenol curing. With any of the selected types of monomer, the FKM rubbers absorbed biodiesel faster and to a greater extent with increasing oxygen partial pressure due to the increase in concentration of the oxidation products of biodiesel. Water-assisted complexation of biodiesel on magnesium oxide and calcium hydroxide particles led to dehydrofluorination of FKM, resulting in an extensive fuel uptake and a decrease in the strain-at-break and the Young's modulus of the rubbers. An increase in the CH2-concentration determined by infrared spectroscopy, and the appearance of biodiesel flakes in scanning electron micrographs of the extracted rubbers, were explained as being due to the presence of insoluble biodiesel grafted onto FKM on the unsaturated sites resulting from dehydrofluorination. The extensibility of the GFLT-type FKM was the least affected on exposure to biodiesel because this rubber contained less unsaturation and metal oxide/hydroxide particles.

  • 6.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Pourrahimi, A. M.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Christian, Sjöstedt
    Martin, Bellander
    Mikael S., Hedenqvist
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Ulf W., Gedde
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Effects of ageing conditions on degradation of acrylonitrile butadiene rubber filled with heat-treated ZnO star-shaped particles in rapeseed biodiesel2017Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The degradation of acrylonitrile butadiene rubber (NBR) after exposure to biodiesel at different oxygen partial pressures in an automated ageing equipment at 80 °C, and in a high-pressure autoclave at 150 °C was studied. The oxidation of biodiesel was promoted by an increase in oxygen concentration, resulting in a larger uptake of fuel in the rubber due to internal cavitation, a greater decrease in the strain-at-break of NBR due to the coalescence of cavity, and a faster increase in the crosslinking density and carbonyl index due to the promotion of the oxidation of NBR. During the high-temperature autoclave ageing, less fuel was absorbed in the rubber, because the formation of hydroperoxides and acids was impeded. The extensibility of NBR aged in the autoclave decreased only slightly due to the cleavage of rubber chains by the biodiesel attack. The degradation of NBR in the absence of carbon black was explained as being due to oxidative crosslinking. The dissolution of ZnO crystals in the acidic components of biodiesel was retarded by removing the inter-particle porosity and surface defects through heat treating star-shaped ZnO particles. The rubber containing heat-treated ZnO particles swelled less in biodiesel than a NBR filled with commercial ZnO nanoparticles, and showed a smaller decrease in the strain-at-break and less oxidative crosslinking.

  • 7.
    Alberdi-Muniain, Ane
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gil-Negrete, N.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Influence of carbon black and plasticisers on dynamic properties of isotropic magnetosensitive natural rubber2012Inngår i: Plastics, rubber and composites, ISSN 1465-8011, Vol. 41, nr 7, 310-317 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic shear modulus of magnetosensitive (MS) natural rubber composites is experimentallystudied, where influences of carbon black, plasticiser and iron particle concentrations areinvestigated at various dynamic shear strain amplitudes and external magnetic fields within thelower structure borne frequency range. The iron particles embedded in natural rubber areirregularly shaped and randomly distributed; the plasticisers simplify the iron particle blendingprocess, while carbon black reduces the production costs and improves the mechanicalproperties. The results show that the relative MS effect on the shear modulus magnitude increaseswith increased plasticiser and iron particle concentration and decreases with increased carbonblack concentration. Furthermore, their relative contributions are quantified. Consequently, thestudy provides a basis for optimising the composition of MS natural rubber to meet a variety ofrequirements, including those of vibration isolation, a promising application area for MS materials.

  • 8.
    Albertsson, A-C.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Andersson, S-O.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    The mechanism of biodegradation of polyethylene1987Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 18, 73-87 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 9. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradation of enhanced environmentally degradable polyethylene in biological aqueous media: mechanisms during the first stages1994Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 51, nr 6, 1097-1105 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 10. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Increased biodegradation of a low-density polyethylene (LDPE) matrix in starch-filled LDPE materials1993Inngår i: Journal of environmental polymer degradation, ISSN 1064-7546, Vol. 1, nr 4, 241-245 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 11. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Solid-phase extraction and gas chromatographic-mass spectrometric identification of degradation products from enhanced environmentally degradable polyethylene1995Inngår i: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 690, nr 2, 207-217 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 12. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Susceptibility of enhanced environmentally degradable polyethylene to thermal and photo-oxidation1992Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 37, nr 2, 163-171 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 13. Albertsson, A-C.
    et al.
    Barenstedt, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Lindberg, T.
    Degradation product pattern and morphology changes as means to differentiate abiotically and biotically aged degradable polyethylene1995Inngår i: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 36, nr 16, 3075-83 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 14. Albertsson, A-C.
    et al.
    Griffin, G. J. L.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Nishimoto, K.
    Watanabe, Y.
    Spectroscopic and mechanical changes in irradiated starch-filled LDPE1994Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 45, nr 2, 173-178 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 15. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Abiotic degradation products from enhanced environmentally degradable polyethylene1994Inngår i: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 45, nr 2, 97-103 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 16. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Aspects of biodeterioration of inert and degradable polymers1993Inngår i: International Biodeterioration & Biodegradation, ISSN 0964-8305, Vol. 31, nr 3, 161-170 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 17. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Biodegradable polymers1992Inngår i: Comprehensive Polymer Science, Supplement Series, Midland, Michigan: Pergamon Press, 1992, 285- s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 18. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Biodegradation and testmethods for environmental and biomedical applications of polymers1990Inngår i: Degradable Materials, Boca Raton: CRC Press, 1990, 263- s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 19. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Chemistry and biochemistry of polymer biodegradation1994Inngår i: Chemistry and Technology of Biodegradable Polymers / [ed] G.J.L. Griffin, London, England: Blackie Academic & Professional , 1994, 7-17 s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 20. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Chromatographic fingerprinting as a means to predict degradation mechanisms1996Inngår i: Journal of environmental polymer degradation, ISSN 1064-7546, Vol. 4, nr 1, 51-3 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 21. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Controlled degradation by artificial and biological processes1996Inngår i: Macromol. Design of Polymeric Materials, Marcel Dekker, 1996, 54- s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 22. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable polyethylene-starch complex1991Inngår i: Makromolekulare Chemie, Macromolecular Symposia, Vol. 48-49, nr Eur. Polym. Fed. Symp. Polym. Mater., 3rd, 1990, 395-402 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 23. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable Polymers1996Inngår i: The Polymeric Materials Encyclopedia: Synthesis, Properties and Applications / [ed] J. C. Salamone, Boca Raton, USA: CRC Press, 1996, 150- s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 24. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable polymers for the future1995Inngår i: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 46, nr 2, 114-123 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 25. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Environment-adaptable polymers1993Inngår i: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 41, nr 3, 345-349 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 26. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Increased biodegradation of LDPE-matrix in starch-filled LDPE materials1992Inngår i: Materials Science and Engineering, Vol. 67, 296-297 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 27. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Macromolecular architecture-nature as model for degradable polymers1996Inngår i: Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, Vol. 33, nr 10, 1565-1570 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 28. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    New tools for analyzing degradation1995Inngår i: Macromolecular Symposia, ISSN 1022-1360, E-ISSN 1521-3900, Vol. 98, nr 35th IUPAC International Symposium on Macromolecules, 1995, 797-801 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 29. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Polyethylene degradation and degradation products1990Inngår i: Agricultural and Synthetic Polymers: Biodegradability and Utilization, American Chemical Society (ACS), 1990, Vol. 433, nr Agricultural & Synthetic Polymers, 60-64 s.Kapittel i bok, del av antologi (Fagfellevurdert)
  • 30. Albertsson, A-C.
    et al.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    The Influence of Biotic and Abiotic Environments on the Degradation of Polyethylene.1990Inngår i: Progress in polymer science, ISSN 0079-6700, E-ISSN 1873-1619, Vol. 15, nr 2, 177-192 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 31. Albertsson, A-C.
    et al.
    Sares, C.
    Karlsson, S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Increased biodegradation of low-density polyethylene (LDPE) with nonionic surfactant1993Inngår i: Acta Polymerica, ISSN 0323-7648, E-ISSN 1521-4044, Vol. 44, nr 5, 243-246 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 32.
    Albertsson, Ann-Christine
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Frontiers in Biomacromolecules: Functional Materials from Nature2012Inngår i: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 13, nr 12, 3901-3901 s.Artikkel i tidsskrift (Annet vitenskapelig)
  • 33.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Edlund, Ulrica
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Barrier layers for packaging laminates and packaging laminates comprising such barrier layers2009Patent (Annet (populærvitenskap, debatt, mm))
  • 34.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Erlandsson, Bengt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Molecular weight changes and polymeric matrix changes correlated with the formation of degradation products in biodegraded polyethylene1999Inngår i: Journal of environmental polymer degradation, ISSN 1064-7546, Vol. 64, 91-99 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products, The samples were thermooxidized for 6 days at 100 degrees C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in (M) over bar(n) from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.

  • 35.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Groning, M.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Emission of volatiles from polymers - A new approach for understanding polymer degradation2006Inngår i: Journal of polymers and the environment, ISSN 1064-7546, E-ISSN 1572-8900, Vol. 14, nr 1, 8-13 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Emission of low molar mass compounds from different polymeric materials was determined and the results from the volatile analysis were applied to predict the degree of degradation and long-term properties, to determine degradation rates and mechanisms, to differentiate between biotic and abiotic degradation and for quality control work. Solid-phase microextraction and solid-phase extraction together with GC-MS were applied to identify and quantify the low molar mass compounds. Volatiles were released and monitored at early stages of degradation before any matrix changes were observed by e.g. SEC, DSC and tensile testing. The analysis of volatiles can thus also be applied to detect small differences between polymeric materials and their susceptibility to degradation. The formation of certain degradation products correlated with the changes taking place in the polymer matrix, these indicator products could, thus, be analysed to rapidly predict the degree of degradation in the polymer matrix and further to predict the long-term properties and remaining lifetime of the product.

  • 36.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Gröning, Mikael
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Chromatographic analysis as a tool for predicting material performance2005Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, 247-248 s.Artikkel i tidsskrift (Annet vitenskapelig)
  • 37.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Degradable polymers and their interaction with the environment2007Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 223, 566-567 s.Artikkel i tidsskrift (Annet vitenskapelig)
  • 38.
    Albertsson, Ann-Christine
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    The three stages in the degradation of polymers- polyethylene as a model substance1988Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 35, 1289-1302 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 39. Albertsson, Ann-Christine
    et al.
    Renstad, Rasmus
    Erlandsson, Bengt
    Eldsäter, Carina
    Karlsson, Sigbritt
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Effect of processing additives on (bio)degradability of film-blown poly(ε-caprolactone)1998Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 70, nr 1, 61-74 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 40.
    Albán Reyes, Diana Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Skoglund, Nils
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå, Sweden .
    Svedberg, Anna
    Eliasson, Bertil
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Sundman, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    The influence of different parameters on the mercerisation of cellulose for viscose production2016Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 2, 1061-1072 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A quantitative analysis of degree of transformation from a softwood sulphite dissolving pulp to alkalised material and the yield of this transformation as a function of the simultaneous variation of the NaOH concentration, denoted [NaOH], reaction time and temperature was performed. Samples were analysed with Raman spectroscopy in combination with multivariate data analysis and these results were confirmed by X-ray diffraction. Gravimetry was used to measure the yield. The resulting data were related to the processing conditions in a Partial Least Square regression model, which made it possible to explore the relevance of the three studied variables on the responses. The detailed predictions for the interactive effects of the measured parameters made it possible to determine optimal conditions for both yield and degree of transformation in viscose manufacturing. The yield was positively correlated to the temperature from room temperature up to 45 A degrees C, after which the relation was negative. Temperature was found to be important for the degree of transformation and yield. The time to reach a certain degree of transformation (i.e. mercerisation) depended on both temperature and [NaOH]. At low temperatures and high [NaOH], mercerisation was instantaneous. It was concluded that the size of fibre particles (mesh range 0.25-1 mm) had no influence on degree of transformation in viscose processing conditions, apparently due to the quick reaction with the excess of NaOH.

  • 41.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Analytical tools for identification and quantification of migrants from food packaging2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Polymers are frequently used as packaging material for food and therefore it is of concern that migrating substances such as additives or degradation products could contaminate the food. Sometimes also processing or microwave heating of food is performed directly inside the food package, which could lead to increased migration. Chromatographic and mass spectrometric analysis techniques can be used to detect, identify and quantify compounds that are released from polymers during such scenarios and, with suitable extraction and analysis techniques for example solid phase micro extraction coupled to gas chromatography – mass spectrometry (SPME-GC-MS), the migrating substances can be identified and quantified. We have previously detected the emission of low molecular weight substances from polymers using SPME-GC-MS [1,2]. With these analysis techniques we have shown that significant antioxidant degradation takes place during microwave heating of the polypropylene (PP) packages in the fatty food simulants, which further led to increased migration of potentially toxic degradation products into the food [3]. No antioxidant degradation was observed in aqueous food simulants or during conventional heating at the same temperature. Electrospray ionization-mass spectrometry (ESI-MS) was shown to be a valuable tool for studying the less volatile migrants. Antioxidant migration rates from three PP materials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials, as determined by high performance liquid chromatography (HPLC) [4]. The extraction efficiency of a headspace - solid phase microextraction (HS-SPME) method could be predicted from the analyte properties using a partial least squares (PLS) regression model [5].

     

    References

    [1] M Gröning, M Hakkarainen, Journal of Chromatography, (2001) 932, 1-11

    [2] M Hakkarainen, Journal of Chromatography, (2003)  1010, 9-16

    [3] J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry, (2011) DOI: 10.1021/jf1048639

    [4] J. Alin and M. Hakkarainen, Journal of Applied Polymer Science, (2010) 118, 1084-1093

    [5] J. Alin and M. Hakkarainen, manuscript

  • 42.
    Alin, Jonas
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Quality control of polymeric packaging and recycled materials by chromatographic and mass spectrometric techniques2011Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    During the lifetime polymers can emit degradation products and additives to the surrounding environment. The development of analytical techniques to identify and quantify migrated compounds is essential to assess the safety of the plastic products. This is especially important when plastic materials are used in demanding or otherwise sensitive applications such as toys, medical products, food packaging or water pipes as well as when new types of polymeric materials such as nanocomposites, degradable materials, functional materials or recycled materials are developed. We have in several studies applied chromatographic and mass spectrometric techniques for analysis of emissions from different polymeric materials. As an example we have shown that microwave heating can lead to accelerated degradation of additives incorporated in the polypropylene (PP)packages, which further led to increased migration of potentially toxic degradation products into the food [1]. Significant antioxidant degradation was shown to take place during microwave heating of the packages in the fatty food simulants, while no degradation of antioxidants was detected during conventional heating of the packages in the fatty food simulants. No antioxidant degradation was observed in aqueous food simulants. Antioxidant migration rates from three PPmaterials to fatty food simulants differed largely with respect to the PP type and increased with decreasing degree of crystallinity in the materials [2]. Stereocomplexation improved the migration resistance of novel polylactide based packaging materials in contact with food simulants [3]. When polymeric materials are recycled one point of concern is the presence of unknown low molecular weight products in the materials. In addition the recycled materials could be more susceptible for further degradation even when further stabilized. We have shown that increasing amounts of degradation products are formed during aging of in-plant recycling of polyamide 6.6[4]. The amount of degradation products could also be correlated to deterioration of material properties such as mechanical properties. The odor coming polypropylene materials containing recycled milled phenol-formaldehyde glass-fiber scrap was shown to be caused by the presence of phenol in the materials [5].

    1. J. Alin and M. Hakkarainen, Journal of Agricultural and Food Chemistry (2011) 59(10), 5418-5427

    2. J. Alin and M. Hakkarainen, Journal of Applied Polymer Science (2010) 118(2), 1084-1093.

    3. Y. Bor, J. Alin and M. Hakkarainen, Packaging Technology and Science, DOI: 10.1002/pts.990.

    4. M. Gröning and M. Hakkarainen, Journal of Applied Polymer Science, (2002) 86, 3396-3407

    5. M. Gröning, H. Eriksson, M. Hakkarainen and A.-C. Albertsson, Polymer Degradation andStability, (2006) 91, 1815-1823

  • 43.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Microwave heating causes rapid degradation of antioxidants in polypropylene packaging leading to greatly increased specific migration to food simulants as shown by ESI-MS and GC-MS2011Inngår i: Journal of Agricultural and Food Chemistry, ISSN 0021-8561, E-ISSN 1520-5118, Vol. 59, nr 10, 5418-5427 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microwave heating of commercial microwavable polypropylene packaging in contact with fatty food simulants caused significant antioxidant degradation and increased specific migration as shown by electrospray ionization-mass spectrometry (ESI-MS) and gas chromatography-mass spectrometry (GC-MS). Degradation of the antioxidants Irgafos 168 and Irganox 1010 was not detected during conventional heating of polypropylene packaging at the same temperature. The migration into aqueous food simulants was primarily restricted by the water solubility of the migrants. Using isooctane as fatty food simulant caused significant swelling and greatly enhanced overall migration values compared to the other fatty food simulant, 99.9% ethanol, or the aqueous food simulants 10% ethanol, 3% acetic acid, or water. ESI-MS spectra clearly reflected the overall migration values, and the number and amount of compounds detected decreased as the hydrophilicity of the food simulant increased. ESI-MS was shown to be an excellent tool for the analysis of semivolatile migrants and a good complement to GC-MS analysis of volatile migrants.

  • 44.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymerteknologi.
    The significant effect of polypropylene material on the migration of antioxidants from food container to food simulants2010Konferansepaper (Annet vitenskapelig)
  • 45.
    Alin, Jonas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Hakkarainen, Minna
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    Type of Polypropylene Material Significantly Influences the Migration of Antioxidants from Polymer Packaging to Food Simulants During Microwave Heating2010Inngår i: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 118, nr 2, 1084-1093 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three different polypropylene materials, polypropylene homopolymer (PP), propylene-ethylene random copolymer (PP-R), and propylene-ethylene copolymer (PP-C) are commonly used in plastic containers designed for microwave heating of food. Migration of antioxidants, Irganox 1010 and Irgafos 168, from PP. PP-R, and PP-C during microwave heating in contact with different food simulants was investigated by utilizing microwave assisted extraction (MAE) and high performance liquid chromatography (HPLC). The polypropylene material significantly influenced the migration rate, which decreased in the order of increasing degree of crystallinity in the materials. PP homopolymer was the most migration resistant of the studied materials especially in contact with fatty food simulants. The use of isooctane as fatty food simulant resulted in rapid depletion of antioxidants, while migration to another fatty food simulant, 96% ethanol, was much more limited. Migration to aqueous and acidic food simulants was in most cases under the detection limits irrespective of microwaving time and temperature. The diffusion coefficients were similar to what have been found previously under similar conditions but without microwaves. The effect of swelling was shown by the large increase in the calculated diffusion coefficients when isooctane was used as food simulant instead of 96% ethanol. (C) 2010 Wiley Periodicals, Inc. I Appl Polym Sci 118: 1084-1093,2010

  • 46.
    Alipour, Nazanin
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymera material.
    Structure and Mechanical/Transport properties of Single and Multilayer Polyethylene-based Materials2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The current study discusses the structure, mechanical and transport properties of polyethylene-based materials into two parts. The first part deals with the migration and chemical depletion of active substance such as insecticides from moulded polyethylene sheets. Deltamethrin (DM) and synergist piperonyl butoxide (PBO) are often used for insect control purpose. It was found that DM as a powder was incapable of recrystallization and remained in liquid state after cooling to room temperature, and that the evaporation of a DM/PBO solution was greater than that predicted from the evaporation rates of pristine separate material components. Infrared spectroscopy and liquid chromatography showed that the loss of DM and PBO through polyethylene sheets was negligible over 30 days, when aged in air at 80 °C (60 and 80 %RH). However, significant migration of the active species was observed in aged polyethylene sheets which were exposed in liquid water (at 80 and 95 °C). In the second part, the structure and properties of multi–layered polymer films were studied in terms of crystallization kinetics, mechanical and transport properties. Previously, it has been shown that when the layer thickness decreases from micrometre-scale to nanometre-scale, leading to improvement of the film performance such as crack propagation and oxygen barrier properties. In this work, two multi-layered systems were considered based on compatible (i) or incompatible layers (ii). In the first case (i), metallocene polyethylene (mPE) and low-density polyethylene (LDPE) where investigated as 2, 24, and 288 adjacent layers. In the second case (ii) poly(ethylene-co-vinyl alcohol) (EVOH) and polyethylene adhesive was evaluated as 5 and 19 layers. The crystallization kinetic studies showed that the crystallization rate was retarded as the layers became thinner with increasing number of layers in the multi-layered films as compared to the reference films (2 and 5 layers). The observation was suggested to stem from greater association between layers (inter layer mixing) in the case of mPE/LDPE films with 2 layers. Furthermore, the crack growth resistance increased with increasing number of layers. The x-ray scattering and tensile testing showed that the films were orientated more in extrusion direction than in the transverse direction, besides the EVOH films (the incompatible system) showed higher orientation in the extrusion direction than mPE/LDPE films. The uptake of n-hexane was reduced significantly in multi-layered EVOH films due to the effective protective role of EVOH. Furthermore, it was revealed that non-homogenous swelling causing a folding/curling of bilayer films when exposed to the vapour of the solvent.

  • 47.
    Alipour, Nazanin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Andersson, Richard L.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Olsson, Richard T.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi.
    VOC-Induced Flexing of Single and Multilayer Polyethylene Films As Gas Sensors2016Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, nr 15, 9946-9953 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The differential swelling and bending of multilayer polymeric films due to the dissimilar uptake of volatile organic compounds (VOCs; n-hexane, limonene) in the different layers was studied. Motions of thin polyethylene films triggered by the penetrant were investigated to learn more about how their deformation is related to VOC absorption. Single layers of metallocene or low-density polyethylene, and multilayers (2-288-layers) of these in alternating positions were considered. Single-, 24-, and 288 layer films displayed no motion when uniformly subjected to VOCs, but they could display simple curving modes when only one side of the film was wetted with a liquid VOC. Two-layer films displayed simple bending when uniformly subjected to VOCs due to the different swelling in the two layers, but when the VOC was applied to only one side of the film, more complex modes of motion as well as dynamic oscillations were observed (e.g., constant amplitude wagging at 2 Hz for ca. 50 s until all the VOC had evaporated). Diffusion modeling was used to study the transport behavior of VOCs inside the films and the different bending modes. Finally a prototype VOC sensor was developed, where the reproducible curving of the two-layer film was calibrated with n-hexane. The sensor is simple, cost-efficient, and nondestructive and requires no electricity.

  • 48. Amer, Wael A.
    et al.
    Wang, Li
    Amin, Abid M.
    Yu, Haojie
    Zhang, Lei
    Li, Chao
    Wang, Yang
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Liquid-crystalline azobenzene-containing ferrocene-based polymers: study on synthesis and properties of main-chain ferrocene-based polyesters with azobenzene in the side chain2013Inngår i: Polymers for Advanced Technologies, ISSN 1042-7147, E-ISSN 1099-1581, Vol. 24, nr 2, 181-190 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ferrocene-based polymers are characterized by their electrochemical activity, good redox properties, thermal, photochemical stability, and liquid crystallinity, and thus they have various applications in different fields. A comprehensive investigation on the synthesis and properties of three novel main-chain ferrocene-based polyesters with azobenzene in the side chain (MFPAS) was carried out. The main-chain ferrocene-based polyester, poly(N-phenyldiethanolamine 1,1'-ferrocene dicarboxylate (PPFD), was synthesized via the solution polycondensation reaction of 1,1'-ferrocenedicarbonyl chloride with phenyldiethanolamine (PDE). The novel MFPAS were synthesized via the post-polymerization azo-coupling reaction of PPFD with three different 4-substituted anilines including 4-nitroaniline, 4-aminobenzoic acid, and 4-aminobenzonitrile to produce 4-nitrophenylazo-functionalized-PPFD (PPFD-NT), 4-carboxyphenylazo-functionalized-PPFD (PPFD-CA), and 4-cyanophenylazo-functionalized-PPFD (PPFD-CN), respectively. All the synthesized polymers were characterized by 1H NMR spectroscopy, Fourier transform infrared spectroscopy, and UVvisible spectroscopy. In addition, powder X-ray diffraction patterns were measured for the synthesized polymers. The photoisomerization of the MFPAS was studied. The thermal properties of the MFPAS were studied using thermogravimetric analysis and differential scanning calorimetry. PPFD-CA and PPFD-CN were found to be more thermally stable than PPFD-NT. Finally, the liquid-crystalline properties of PPFD and the MFPAS were examined using polarized optical microscope. It was found that all the polymers possessed nematic phases and exhibited textures with schlieren disclinations.

  • 49. Amer, Wael A.
    et al.
    Wang, Li
    Yu, Haojie
    Amin, Abid M.
    Wang, Yang
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Synthesis and Properties of a Ferrocene-based Metallomesogenic Polymer Containing Bis(4-hydroxyoctoxyphenyl)sulfone2012Inngår i: Journal of Inorganic and Organometallic Polymers and Materials, ISSN 1574-1443, Vol. 22, nr 6, 1229-1239 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Poly[bis(4-hydroxyoctoxyphenyl)sulfone 1,1'-ferrocene dicarboxylate] (PHOSFD) was synthesized by solution polycondensation reaction of bis(4-hydroxyoctoxyphenyl)sulfone with 1,1'-ferrocenyl chloride. The synthesized polymer was characterized via the measurement of its H-1 NMR spectrum, UV-Vis spectrum and FTIR spectrum. X-ray diffraction pattern was measured to investigate the crystallinity of the synthesized polymer and it was found that the polymer is mostly amorphous. The molecular weight of the polymer was determined by gel permeation chromatography. In addition, the electrochemical, the thermal, and the liquid crystalline properties of the synthesized polymer were examined and compared with the properties of poly(diethyleneglycol 1,1'-ferrocene dicarboxylate) (PDEFD) that was synthesized in our earlier study. The electrochemical processes of PHOSFD in CH2Cl2 were confirmed neither to be totally reversible nor completely irreversible. Generally, the electrochemical properties of PHOSFD and PDEFD were found to be similar to each other. PHOSFD was found to be thermally stable but its thermal stability is lower than that of PDEFD. Both of PHOSFD and PDEFD showed liquid crystalline properties and they possessed nematic phase textures with schlieren disclinations during heating and cooling.

  • 50.
    Aminlashgari, Nina
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik, Polymerteknologi.
    LDI-MS strategies for analysis of polymer degradation products, additives and drugs2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The advancement of mass spectrometry (MS) has been and continues to be a prominent analytical technique for highly accurate determination of analytes. The goal of this thesis was to develop new laser desorption ionization-mass spectrometric (LDI-MS) methods for analysis of polymer degradation products, additives and drugs. Modifications in the sample preparation were evaluated in the presence and absence of surface assisting materials. Various nanoparticles were evaluated as effective absorbents for energy transfer in the LDI procedure of the small molecules.

    In paper I and II, LDI-MS methods were developed for following the progression of chemical reactions. First, the procedure to optimize microwave assisted hydrothermal degradation products of cellulose were analyzed; second, the synthesis of glucose hexanoate ester plasticizers was monitored as a function of reaction time. The LDI-MS method provided rapid detection for the elucidation of the chemical products and their relative ratios. In contrast, the electrospray ionization-mass spectrometry (ESI-MS) analysis produced a noisy spectrum primarily containing peaks from salt clusters. A surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) method was developed in paper III enabling the identification of poly(e-caprolactone) and its degradation products by using nanoparticles as the substrate. Similar analysis by matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) was not as successful due to convolution of the analyte peaks with clusters released from the matrix. ESI-MS analysis verified the SALDI-MS method as comparable degradation product patterns were observed. Furthermore, the possibility of using polylactide based nanocomposites as surfaces in the analysis of drugs was evaluated in paper IV. An advantage was the ease of handling compared to the use of free nanoparticles. Paper V introduces the potential of direct examination of oxygen plasma modified parylene C surfaces by a LDI-MS methodology. 

1234567 1 - 50 of 775
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf