Digitala Vetenskapliga Arkivet

Change search
Refine search result
1 - 31 of 31
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Agde Tjernlund, Jessica
    et al.
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Gamstedt, Kristofer
    KTH, Superseded Departments (pre-2005), Solid Mechanics.
    Xu, Zhi-Hui
    KTH, Superseded Departments (pre-2005), Materials Science and Engineering.
    Influence of molecular weight on strain-gradient yielding in polystyrene2004In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 44, no 10, p. 1987-1997Article in journal (Refereed)
    Abstract [en]

    Experimental observations have indicated that the presence of strain gradients has an influence on the inelastic behavior of polymers as well as in other materials such as ceramics and metals. The present study has experimentally quantified length-scale effects in inelastic deformations of the polymer material polystyrene (PS) with respect to the molecular length. The experimental technique that has been used is nano-indentation to various depths with a Berkovich indenter. The hardness has been calculated with the method by Oliver and Pharr, and also by direct measurements of the area from atomic force microscopy. The experiments showed that the length-scale effects in inelastic deformations exist in polystyrene at ambient conditions. The direct method gave a smaller hardness than the Oliver-Pharr method. It was also shown that the length-scale parameter according to Nix and Gao increases with increasing molecular weight. For high molecular weights above a critical value of entanglement, there was no pertinent increase in the length-scale parameter. The length-scale parameter for strain-gradient plasticity has a size of around 0.1 μm for polystyrene.

  • 2. Arino, I.
    et al.
    Kleist, U.
    Mattsson, Lars
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Metrology and Optics.
    Rigdahl, M.
    On the relation between surface texture and gloss of injection-molded pigmented plastics2005In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, no 10, p. 1343-1356Article in journal (Refereed)
    Abstract [en]

    The relation between the surface topography of injection-molded plastic objects with deliberately imposed textures and their gloss, measured by means of a conventional glossmeter at incident angles of 20 degrees, 60 degrees and 85 degrees, was investigated. A modification of the general scalar Kirchhoff approximation, which accounts for geometrical features of the glossmeter, is used to describe the experimental gloss values of the textured surfaces. The agreement between the measured and the calculated values for incidence angles of 20 degrees and 60 degrees confirms the usefulness of the approach, though several of the textured surfaces used here are too rough for the Kirchhoff theory to be strictly valid. A poorer agreement, however, was noted at higher incidence angles (85 degrees in this case). For very smooth surfaces (without any texture), the classical Bennett-Porteus theory could in many cases describe the gloss level with sufficient accuracy. The influence on the measured gloss of the polymer material (in terms of its refractive index) and the color of the injection-molded object is also discussed. Light beige specimens in three different polymeric materials (acrylonitrile-butadiene-styrene, acrylonitrile-butadiene-styrene/polycarbonate blend, and polypropylene) as well as three acrylonitrile-butadiene-styrene products with different colors were used. The refractive index of the polymer had no major influence on the measured gloss. The gloss level increased slightly with increasing lightness of the specimens, which can be associated with an increased contribution from the bulk scattering. However, the surface texture governed most of the gloss variations.

  • 3.
    Bekin, Seda
    et al.
    Department of Chemical Engineering, Faculty of Engineering, Istanbul University.
    Sarmad, Shokat
    Department of Chemical Engineering, Faculty of Engineering, Istanbul University.
    Gürkan, Koray
    Department of Electrical and Electronics Engineering, Faculty of Engineering, Istanbul University.
    Yenici, Gökcen
    Department of Chemical Engineering, Faculty of Engineering, Istanbul University, Avcilar.
    Keceli, Gönül
    Department of Chemistry, Faculty of Engineering, Istanbul University.
    Gürdag, Gülten
    Department of Chemical Engineering, Faculty of Engineering, Istanbul University.
    Dielectric, thermal, and swelling properties of calcium ion crosslinked sodium alginate film2014In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 54, no 6, p. 1372-1382Article in journal (Refereed)
  • 4. Camacho, W.
    et al.
    Karlsson, Sigbritt
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    NIR, DSC, and FTIR as quantitative methods for compositional analysis of blends of polymers obtained from recycled mixed plastic waste2001In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 41, no 9, p. 1626-1635Article in journal (Refereed)
    Abstract [en]

    Methods for the determination of the composition of two binary blends in mixtures of recycled polymeric materials were analyzed and compared. Recycled polypropylene/polyethylene (PP/HDPE) and recycled poly(acryl-butadiene-styrene) and polypropylene(ABS/PP) were used to develop and validate the methods. Diffuse reflectance near infrared spectroscopy (NIRS) offers high sensitivity and ease of operation and a possibility to perform multivariate data analysis. In comparison, differential scanning calorimetry (DSC) and Mid-IR which are commonly used for this purpose require certain sample preparation and are indeed time consuming. In addition, the low sensitivity of these two methods to concentrations lower than 1% wt makes their application in quality control of recycled polymers inappropriate. NIR can be used for estimating the composition of the recyclate on-line in only a few seconds, no sample preparation is required, and high precision is achieved. We obtained a root mean square error of prediction (RMSEP) equal to 0.21% wt in the interval from 0-15% wt of PP in HDPE and a RMSEP equal to 0.91% wt in the interval 0-100%. For blends of PP/ABS a RMSEP of 0.74% wt in the range 0-100% and 0.32% wt in the range 0-15% wt PP was calculated. Most of the variation in the spectral data with respect to the polymer blend composition for all the studied blends were explained by two principal components (PC). The optimal number of factors (PC) was determined by cross-validation analysis.

  • 5. Flodberg, G.
    et al.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Gedde, Ulf W.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Barrier properties of injection molded blends of liquid crystalline polyesters (Vectra) and high-density polyethylene2003In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 43, no 5, p. 1044-1057Article in journal (Refereed)
    Abstract [en]

    Blends of an extrusion-grade high-density polyethylene and two liquid crystalline copolyesters (LCP; Vectra A950 and Vectra RD501) were prepared by melt mixing and injection molding, and the. morphologies and oxygen permeabilities of the blends were assessed. Scanning electron microscopy revealed that the LCP was present in the blends as mixed oriented bands and small spheres at low LCP contents (4-9 vol%), Whereas blends with more than 18 vol% LCP showed LCP lamellae of macroscopic lateral size (mm). Scanning electron microscopy revealed a two-dimensional continuity of the LCP domains in the disc plane due to radial shear deformation and circumferential stretching of the melt leaving the central gate of the disc-shaped cavity. The oxygen permeability, diffusivity and solubility decreased with increasing LCP content of the blends. The decrease in permeability with respect to polyethylene was significant (46%-55%) already at 9 vol% LCP. At 27 vol% LCP, the decrease with respect to polyethylene, was 92% for the Vectra A950 blend and 98% for the Vectra RD501 blend. These blends showed a greater decrease in diffusivity (86%-92%) than in solubility (39%-76%) with respect to polyethylene, which showed the very pronounced effect of the LCP lamellae on the geometrical impedance factor. Microvoids were present in all the blends despite the use of a very high injection pressure (180 MPa) but their impact on the oxygen permeability was negligible for the Vectra. RD501 blends and relatively small for the Vectra A950 blends.

  • 6. Flodberg, G.
    et al.
    Hellman, A.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Sadiku, E. R.
    Gedde, Ulf W.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Barrier properties of blends based on liquid crystalline polymers and polyethylene2000In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 40, no 9, p. 1969-1978Article in journal (Refereed)
    Abstract [en]

    Blends of an extrusion-grade polyethylene and two different liquid crystalline polymers of Vectra type were prepared by melt mixing using poly(ethylene-co-methacrylic acid) as compatibilizer. Oxygen and water vapor permeability, transparency and welding strength of compression molded and film blown specimens were studied. The compression molded blends showed gas permeabilities conforming to the Maxwell equation assuming low permeability liquid crystalline polymer spheres in a high permeability polyethylene matrix One of the liquid crystalline polymers with suitable rheological properties formed a more continuous phase in the film blown blends and a substantial decrease in oxygen and water vapor permeability was observed in these blends. The compression molded blends with 50% liquid crystalline polymer and some of blow molded blends showed very high gas permeabilities. It is believed that voids forming continuous paths through the structure were present in these samples. The blends showed significantly higher opacity than pure polyethylene.

  • 7.
    Forsgren, Lilian
    et al.
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser. Chalmers University of Technology, Sweden.
    Thunberg, Johannes
    Chalmers University of Technology, Sweden.
    Rigdahl, Mikael
    Chalmers University of Technology, Sweden.
    Boldizar, Antal
    Chalmers University of Technology, Sweden.
    Injection Molding and Appearance of Cellulose-Reinforced Composites2019In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 60, no 1, p. 5-12Article in journal (Refereed)
    Abstract [en]

    Composite materials based on an ethylene-acrylic acid (EAA) copolymer and 20 wt% cellulose fibers were compounded by two runs in a twin-screw extruder. The composite material with cellulose fibers (CF) and a reference of unfilled EAA were injection molded into plaques using three different temperature profiles with end zone temperatures of 170°C, 200°C, and 230°C. The injection molded samples were then characterized in terms of their mechanical properties, thermal properties, appearance (color and gloss), and surface topography. The higher processing temperatures resulted in a clear discoloration of the composites, but there was no deterioration in the mechanical performance. The addition of cellulose typically gave a tensile modulus three times higher than that of the unfilled EAA, but the strength and strain at rupture were reduced when fibers were added. The processing temperature had no significant influence on the mechanical properties of the composites. Gloss measurements revealed negligible differences between the samples molded at the different melt temperatures but the surface smoothness was somewhat higher when the melt temperature was increased. In general, addition of the cellulose to the EAA reduced the gloss level and the surface smoothness.

  • 8.
    Guo, Zengwei
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF.
    Hagström, Bengt
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF. Chalmers University of Technology, Sweden.
    Preparation of polypropylene/nanoclay composite fibers2013In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 53, no 10, p. 2035-2044Article in journal (Refereed)
    Abstract [en]

    Melt spinning of nanoclay (NA)/polypropylene (PP) composites into textile fibers is studied. The synthetic NA Perkalite F100 is prone to be exfoliated in PP matrix. With the help of a maleic anhydride-grafted low-molecular-weight PP as compatibilizer (Epolene E43), a highly exfoliated PP/NA composite was successfully prepared. However, the prepared PP/NA composite shows a poor spinnability because of the phase separation between Epolene E43 and PP matrix. The combination of two different groups of compatibilizers, which are Polybond 1001 (acrylic acid-grafted PP) for the dispersion of NA and Epolene G3216 (maleic anhydride-grafted PP-based copolymer) for the exfoliation of NA, can solve this problem. The PP/NA composite prepared by these two compatibilizers can be smoothly spun into fiber at the NA concentration below 1.9 wt%, which is found to be the percolation concentration of formation of NA network structure in PP matrix.

  • 9.
    Hedenqvist, Mikael S.
    et al.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Ritums, Janis
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Conde-Brana, M.
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Bergman, Gunnar
    KTH, Superseded Departments (pre-2005), Fibre and Polymer Technology.
    Structure and properties of poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride exposed to water, hydrochloric acid, hydrobromic acid and tetrachloroethylene2004In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 44, no 1, p. 113-122Article in journal (Refereed)
    Abstract [en]

    The transport of water, hydrochloric acid. hydrobromic acid and tetrachloroethylene in poly(ethylene-co-chlorotrifluoroethylene) and polyvinylidene fluoride were studied at 70degreesC by the sorption/desorption technique. The effects on the structure and mechanical properties were studied using size-exclusion chromatography, infrared spectroscopy, differential scanning calorimetry and tensile testing. Solute concentrations in the polymers indicated that both the water and HCl/HBr components diffused into the polymers on exposure to acid solutions. The calculated water contents of the diffusing acids generally differed from the water content in the solution. The ratio of water content in the diffusing acid to that in the surrounding acid solution was generally a function of the relative vapor activity of water and HCl/HBr. It was possible to describe the 35% HCl and 47% HBr desorption data using a two-component model. It was assumed that the water and HCl/HBr diffused separately, each having its own constant diffusion coefficient. The water diffusivity was obtained from the pure water system, and this allowed the HCl/HBr diffusivity to be calculated. It was found that the diffusivity decreased, in a non-simple way, as a function of solute size. The exposure to solute did not lower the molar mass of the polyvinylidene fluoride. Differential scanning calorimetry indicated the development of low-melting point polyvinylidene fluoride crystals during the exposure to all solutes. This seemed to be a consequence of the long-term exposure (175 to 376 days) at 70degreesC. The long-term exposure stiffened several of the polyvinylidene fluoride resins and occasionally made them less ductile. The poly(ethylene-co-chlorotrifluoroethylene) also became stiffer, but it was otherwise unaffected as far as observation by the other available techniques was concerned.

  • 10.
    Karlsson, Sigbritt
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    Biodegradable Polymers1998In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 38, no 8, p. 1251-Article in journal (Refereed)
  • 11.
    Knudsen, Daniel
    et al.
    Portland State Univ, Dept Chem, Portland, OR 97207 USA .
    Harnish, Bernadette
    Toth, Ramona
    Yan, Mingdi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Creating Microstructures on Silicon Wafers Using UV-Crosslinked Polystyrene Thin Films2009In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 49, p. 945-948Article in journal (Refereed)
    Abstract [en]

    We report that UV-crosslinked polystyrene (PS) thin films can be used as an inexpensive wet chemical etch resist to create microstructures on silicon wafers. When spin-coated PS films were irradiated, the polymer undergoes UV-induced crosslinking. Patterned PS films were successfully used as the protective layer withstanding chemical etching with the buffered HF solution. Removal of the polymer films by sonicating in water generated microstructures in silicon wafers. This simple and environmentally friendly procedure employs inexpensive commodity polymer and eliminates the use of organic solvents and harsh conditions in the subsequent development process. POLYM. ENG. SCI., 49:945-948, 2009. (C) 2009 Society of Plastics Engineers

  • 12. Kornmann, X.
    et al.
    Thomann, R.
    Mulhaupt, R.
    Finter, J.
    Berglund, Lars A.
    High performance epoxy-layered silicate nanocomposites2002In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 42, no 9, p. 1815-1826Article in journal (Refereed)
    Abstract [en]

    High performance epoxy-layered silicate nanocomposites based on tetra-glycidyl 4,4'-diamino-diphenyl methane (TGDDM) resin cured with 4,4'-diaminodiphenyl sulfone (DDS) have been successfully synthesized. Fluorohectorites modified by means of interlayer cation exchange of sodium cations for protonated dihydro-imidazolines and octadecylamine were used. Fluorohectorite exchanged with 1-methyl-2-norstearyl-3-stearnoacid-amidoethyl-dihydro-imidazolinium ions was immiscible with the epoxy matrix. In contrast, fluorohectorites exchanged with hydroxyethyl-dihydro-imidazolinium (HEODI) and ricinyl-dihydro-imidazolinium ions (RDI) favored the formation of a nanocomposite structure. This is most likely due to the presence of -OH groups in their molecular structure, which has a catalytic effect on the polymerization occurring between the silicate layers. The diffusion of epoxy and curing agent molecules between the silicate layers is also promoted. Microscopy observations revealed that the dispersion of the silicate aggregates on a microscale was proportional to the degree of separation of the silicate layers on a nanoscale. Decreased apparent glass transition temperature was observed in all the nanocomposites. Finally, mechanical property studies showed that epoxy-layered silicate nanocomposite formation could simultaneously improve fracture toughness and Young's modulus, without adversely affecting tensile strength.

  • 13.
    Kornmann, Xavier
    et al.
    Luleå University of Technology.
    Berglund, Lars A.
    Luleå University of Technology.
    Sterte, Johan
    Giannelis, E.P.
    Department of Materials Science and Engineering, Cornell University Ithaca.
    Nanocomposites based on montmorillonite and unsaturated polyester1998In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 38, no 8, p. 1351-1358Article in journal (Refereed)
    Abstract [en]

    The concept of nanoscale reinforcement provides opportunity for synthesis of new polymer materials with unique properties. Montmorilonite (MMT) was derived from bentonite, purified, activated by sodium ions and mixed with reacting unsaturated polyester (UP). X-ray and transmission electron microscopy data were in support of the formation of a partially delaminated nanocomposite material. At an MMT content of only 1.5 vol%, the fracture energy, GQ of the nanocomposite was doubled, 138 J/m2 as compared with 70 J/m2 for the pure UP.

  • 14.
    Kornmann, Xavier
    et al.
    Luleå University of Technology.
    Berglund, Lars A.
    Luleå University of Technology.
    Thormann, R.
    Freiburg Materials Research Centre, Institute for Macromolecular Chemistry, Albert-Ludwigs-Universität.
    Mulhaupt, R.
    Freiburg Materials Research Centre, Institute for Macromolecular Chemistry, Albert-Ludwigs-Universität.
    Finter, J.
    Vantico AG.
    High performance epoxy-layered silicate nanocomposites2002In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 42, no 9, p. 1815-1826Article in journal (Refereed)
    Abstract [en]

    High performance epoxy-layered silicate nanocomposites based on tetra-glycidyl 4,4 prime -diamino-diphenyl methane (TGDDM) resin cured with 4,4 prime -diaminodiphenyl sulfone (DDS) have been successfully synthesized. Fluorohectorites modified by means of interlayer cation exchange of sodium cations for protonated dihydro-imidazolines and octadecylamine were used. Fluorohectorite exchanged with 1-methyl-2-norstearyl-3-stearinoacid-amidoethyl-dihydro-imidazolinium ions was immiscible with the epoxy matrix. In contrast, fluorohetorites exchanged with hydroxyethyl-dihydro-imidazolinium (HEODI) and ricinyl-dihydro-imidazolinium ions (RDI) favored the formation of a nanocomposite structure. This is most likely due to the presence of -OH groups in their molecular structure, which has a catalytic effect on the polymerization occurring between the silicate layers. The diffusion of epoxy and curing agent molecules between the silicate layers is also promoted. Microscopy observations revealed that the dispersion of the silicate aggregates on a microscale was proportional to the degree of separation of the silicate layers on a nanoscale. Decreased apparent glass transition temperature was observed in all the nanocomposites. Finally, mechanical property studies showed that epoxy-layered silicate nanocomposite formation could simultaneously improve fracture toughness and Young's modulus, without adversely affecting tensile strength

  • 15. Krook, M.
    et al.
    Albertsson, Ann-Christine
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Gedde, Ulf W.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Barrier and mechanical properties of montmorillonite/polyesterarnide nanocomposites2002In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 42, no 6, p. 1238-1246Article in journal (Refereed)
    Abstract [en]

    The barrier and mechanical properties of biodegradable melt-mixed polyesteramide/octadecylamine-treated montmorillonite clay (filler) have been studied. Extruded films containing 5 and 13 wt% filler were prepared by melt-mixing. Samples compression molded after extrusion was also studied. Oxygen and water transmission rates were measured. X-ray diffraction was used to assess the periodic distance of the clay layers and transmission electron microscopy was used to assess the composite morphology. An increase of the periodic distance from 23.7 Angstrom for pure filler to 32-36 Angstrom for the processed composites was observed. This suggested that the collapsed stacks of clay particle of the first order X-ray reflection became intercalated upon extrusion. A decrease in the intensity with increasing rotation speed was observed, which suggested that higher shear rates promoted delamination, especially in composites with higher filler content. Transmission electron microscopy indicated that a sizable portion of the clay stacks were delaminated into smaller aggregates, containing generally one to three clay sheets. Density measurements indicated that shear-induced voids were formed in the nanocomposite, and these were, according to transmission electron microscopy, almost exclusively located between the clay sheets. The presence of voids limited the improvement in barrier properties with increasing filler content. However, the very large improvement in stiffness and strength with filler content indicated that these properties were unaffected by these voids.

  • 16. Krook, M.
    et al.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Hellman, A.
    Iversen, T.
    Gedde, Ulf W.
    KTH, Superseded Departments (pre-2005), Polymer Technology.
    Barrier and mechanical properties of pulp fiber/polymer laminates and blends2000In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 40, no 1, p. 143-156Article in journal (Refereed)
    Abstract [en]

    Paperboard laminates coated with two grades of poly(epsilon-caprolactone) (PCL), poly(hydroxy butyrate-co-valerate) (PHBV) or a liquid crystalline copolyester (LCP) were prepared by compression molding, and the influence of the processing conditions and polymer content of the laminate on the laminate properties was studied. Ligno-cellulose fiber/polymer blends were prepared from wet pulps and PCL and PHBV. The morphology, water vapor transmission rates, creasability, curl and twist and mechanical properties of the laminates and blends were studied. LCP and slowly cooled high molar mass PCL laminated paperboards showed the best creasing properties and the paperboards that were penetrated by the polymer showed the smallest degree of curl and twist. Extensive penetration occurred during compression molding of the paperboard with the low molar mass PCL at all temperatures and with PHBV and LCP at the higher molding temperatures. The water vapor transmission rates ranged from 1 to 300 times that of polyethylene depending on the polymer used and on the thermal history. In the case of blends, competitive properties were obtained only in those with a high polymer content. The laminate stiffness decreased and the strength increased in two polymer concentration regions, at similar to 20 wt% due to fiber-fiber separation and at similar to 60 wt% due to phase inversion.

  • 17. Krook, M.
    et al.
    Morgan, G.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Barrier and mechanical properties of injection molded montmorillonite/polyesterarnide nanocomposites2005In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, no 1, p. 135-141Article in journal (Refereed)
    Abstract [en]

    Properties of injection-molded biodegradable polyester-amide composites containing 5 and 13 wt% octadecylammonium-treated montmorillonite clay have been studied. Oxygen transmission rates and mechanical properties were measured. X-ray diffraction was used to assess the degree of intercalation of the clay layer stacks, and transmission electron microscopy (TEM) was used to assess the morphology and degree of layer delamination. A substantial reduction in oxygen permeability was observed when clay was added to the composites. The oxygen permeability of the 13 wt% clay sample was only 20% of that of the pure polymer. The in-plane stiffness and in-plane strength of the sheets were greatly improved without any embrittlement. These beneficial effects were probably due to the high degree of clay layer exfoliation and orientation observed by TEM. Heat shrinkage, toughness analysis, and cutting operations suggested that the polymer chains and the clay layers were oriented parallel to the plane of the sheet. TEM and X-ray showed that stacked layers were still present but that these were significantly intercalated. The clay-layer periodic spacing increased from 25 Angstrom to approximately 35 Angstrom during processing.

  • 18.
    Mathew, Aji P.
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Gong, Guan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Björngrim, Niclas
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Wood Science and Engineering.
    Wixe, David
    Luleå University of Technology.
    Oksman, Kristiina
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Moisture absorption behaviour and its impact on the mechanical properties of polyvinyl acetate (PVAc) based cellulose nanocomposites2011In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 11, p. 2136-2142Article in journal (Refereed)
    Abstract [en]

    Cellulose nanowhisker (CNW) reinforced polyvinyl acetate (PVAc) nanocomposites were prepared by melt-extrusion using a master batch process. Microscopy images showed no visible aggregation of whiskers in the matrix. The influence of CNWs and moisture absorption on the mechanical behavior of the nanocomposites was studied. The water sorption studies indicated low water uptake (<10 wt%) for all the materials. However, higher moisture uptake was obtained in the nanocomposites compared to the matrix though the diffusion co-efficient of the nanocomposites was lower. The tensile strength and modulus were decreased with the addition of CNWs to PVAc, but the reduction is lower at higher CNW concentration indicating that the plasticizing effect of the moisture was counteracted to some extent by the reinforcing effect of CNWs. Higher tensile ductility and toughness, which were dependent on moisture absorption, were achieved in the nanocomposites than pure PVAc.

  • 19.
    Olasz, Lorant
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Gudmundson, Peter
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Prediction of residual stresses in cross-linked polyethylene cable insulation2005In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, no 8, p. 1132-1139Article in journal (Refereed)
    Abstract [en]

    Modeling of the manufacturing process of high-voltage power cables was performed with the aim of predicting residual stresses in the cable insulation. A viscoelastic power law-type constitutive model was used which incorporates temperature and crystallinity dependence of the parameters. In this way the mechanical problem is coupled to the heat transfer and crystallization problems. In order to illustrate the effects of relaxation, a comparison to a thermoelastic material model is made.

  • 20.
    Olsson, Richard T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ström, Valter
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Deng, J.
    Savage, S. J.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Core-Shell Structured Ferrite-Silsesquioxane-Epoxy Nanocomposites: Composite Homogeneity and Mechanical and Magnetic Properties2011In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 5, p. 862-874Article in journal (Refereed)
    Abstract [en]

    Epoxy-based composites of ferrite nanoparticles (50 nm) with 3-glycidoxypropyl- (GPTMS), aminopropyl(APTMS), or methyl-silsesquioxane (MTMS) coatings are reported. The GPTMS coatings (30-nm thick) allowed uniform particle dispersion in the epoxy and prevented sedimentation of the nanoparticles, whereas the APTMS-coated particles formed agglomerates, leading to particle sedimentation. The particles with the thinnest coating (MTMS - 3 nm) agglomerated in the composites without sedimentation. The composites based on GPTMS-coated particles showed higher fracture toughness than the composites based on MTMS-coated particles. The uniformity and thickness of the coatings were related to alcohol composition of the coating media. Coating removal by a novel ultrasonic etching allowed precise determination of the effective ferrite content in the coated nanoparticles. A markedly lower coercivity for nanoparticles without coatings as compared with the nanoparticles with thicker coatings was observed. The saturation magnetization and the coercivity of the composites were independent of coating and casting procedures.

  • 21. Ritums, J. E.
    et al.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Bergman, G.
    Prodan, T.
    Emri, I.
    Sorption behavior in polymers above T-g: Relations between mechanical properties and swelling in limonene2005In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, no 9, p. 1194-1202Article in journal (Refereed)
    Abstract [en]

    The sorption behavior of two highly swelling rubbery polymers, natural rubber and polyethylene, has been studied. The polymers are in many aspects very different. Yet, when the solute mass uptake, in this case limonene, is plotted as a function of the square root of time, both polymers show similar sigmoidal-types of curves. This triggered the research to determine what mechanisms were responsible for the observed similarities and if the degree in sigmoidal behavior and swelling anisotropy could be easily assessed explicitly by any mechanical parameter. It was found that their degrees of swelling anisotropy, described by a solute-surface-concentration relaxation time, could be explained by their relative bulk moduli. It was assumed that the ratio in bulk modulus at zero pressure, determined from compression measurements, could represent the ratio in expansion bulk modulus during swelling. However, the prediction in swelling anisotropy during sorption using the ratio in bulk modulus was slightly less successful when the swelling anisotropy was quantified as the relative ratio of sheet thickness to cross-sectional area side length. It should be noted that the ratio in uniaxial tensile modulus between polyethylene and natural rubber was several orders of magnitude higher than their ratio in swelling anisotropy. The natural rubber sheet became saddle-shaped during limonene sorption and collapsed into a flat shape when the saturation concentration was approached. During desorption, the sheet went from flat to cup-shaped and then flat again at the end of desorption. The saddle and cup shapes occurred in both square and round sheets. These shapes are believed to be a consequence of buckling and deformation due to instabilities in the stress state of the sheet This was, in turn, explained by the normally existing local variation in cross-link density.

  • 22. Römhild, Stefanie
    et al.
    Hedenqvist, Mikael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Bergman, G.
    The Effect of Water Activity on the Sorption and Diffusion of Water in Thermosets Based on Polyester, Vinyl Ester, and Novolac Resins2012In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 52, no 4, p. 718-724Article in journal (Refereed)
    Abstract [en]

    In this work, the transport properties of water in various thermoset resins typically used for fiber-reinforced plastic process equipment (vinyl ester, novolac, bisphenol-A-epoxy-based polyester, and urethane-modified vinyl ester) were systematically studied with a focus on the effects of water activity. Sorption and desorption studies were carried out in aqueous solutions (water activity = 0.78–1) with different salts (NaCl, MgCl2, Na2SO4, and KCl) and one nonionic substance (sucrose) within the temperature interval 65–95°C. It was found that the water concentration in thermoset resins with different chemical structures could be predicted from the water activity, regardless of the actual solute (salt or sucrose) in the aqueous solution. The water quasi-equilibrium concentration decreased with decreasing water activity, whereas the average diffusion coefficient was considered to be independent of water activity in the studied water activity range. A relationship, based on a power law fit, was established describing the water concentration as a function of the water activity and the concentration of pure water. The relationship was independent of resin chemistry and temperature.

  • 23.
    Römhild, Stefanie
    et al.
    RISE, Swerea, Swerea KIMAB.
    Hedenqvist, M.S.
    Royal Institute of Technology.
    Bergman, Gunnar
    RISE, Swerea, Swerea KIMAB.
    The effect of water activity on the sorption and diffusion of water in thermosets based on polyester, vinyl ester, and novolac resins2012In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 52, no 4, p. 718-724Article in journal (Refereed)
    Abstract [en]

    In this work, the transport properties of water in various thermoset resins typically used for fiber-reinforced plastic process equipment (vinyl ester, novolac, bisphenol-A-epoxy-based polyester, and urethane-modified vinyl ester) were systematically studied with a focus on the effects of water activity. Sorption and desorption studies were carried out in aqueous solutions (water activity = 0.78-1) with different salts (NaCl, MgCl 2, Na 2SO 4, and KCl) and one nonionic substance (sucrose) within the temperature interval 65-95°C. It was found that the water concentration in thermoset resins with different chemical structures could be predicted from the water activity, regardless of the actual solute (salt or sucrose) in the aqueous solution. The water quasi-equilibrium concentration decreased with decreasing water activity, whereas the average diffusion coefficient was considered to be independent of water activity in the studied water activity range. A relationship, based on a power law fit, was established describing the water concentration as a function of the water activity and the concentration of pure water. The relationship was independent of resin chemistry and temperature. © 2012 Society of Plastics Engineers.

  • 24.
    Soroudi, Azadeh
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. University of Boras.
    Skrifvars, Mikael
    University of Borås, Faculty of Textiles, Engineering and Business.
    Electro-conductive polyblend fibers of Polyamide-6/polypropylene/polyaniline: electrical, morphological and mechanical characteristics2012In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 52, no 7, p. 1606-1612Article in journal (Refereed)
    Abstract [en]

    Melt spun drawn fibers were prepared using a ternary blend of PP/PA6/PANI-complex (polypropylene/polyamide-6/polyaniline-complex). Their electrical and mechanical properties were compared to those of binary blend fibers of PP/PANI-complex. The results of the morphological studies on 55:25:20 PP/PA6/PANI-complex ternary fibers were found to be in accordance with the predicted morphology for the observed conductivity vs. fiber draw ratio. The scanning electron microscopy (SEM) micrographs of the ternary blend illustrated at least a three-phase morphology of a matrix/core-shell dispersed phase style, with widely varying sizes of droplets. This resulted in a dispersed morphology that, in some parts of the blend, approached a bicontinuous/dispersed phase morphology due to coalescence of the small droplets. The matrix was PP and the core-shell dispersed phase was PA6 and PANI-complex, in which a part of the PANI-complex had encapsulated the PA6 phase and the remaining was solved/dispersed in the PA6 core, as later confirmed by X-ray mapping. When the ternary blend fibers were compared to the binary fibers, the formers were able to combine better conductivity (of an order of 10−3 S cm−1) with a greater tensile strength only at a draw ratio of 5. This indicated that the draw ratio is more critical for the ternary blend fibers, because both conductivity and tensile strength depended on the formation of fibrils from the core-shell dispersed phase of the PA6/PANI-complex.

  • 25.
    Strååt, Martin
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Boldizar, A.
    Chalmers University of Technology.
    Rigdahl, M.
    Chalmers University of Technology.
    Hagström, Bengt
    Swerea IVF Institute of Research.
    Improvement of melt spinning properties and conductivity of immiscible polypropylene/polystyrene blends containing carbon black by addition of styrene-ethylene-butene-styrene block copolymer2011In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 6, p. 1165-1169Article in journal (Refereed)
    Abstract [en]

    Conducting polymeric materials prepared from immiscible blends, such as polypropylene (PP)/polystyrene (PS), together with carbon black (CB), are known to have a relatively high electrical conductivity, because of a selective distribution of CB (double percolation). Melt spinning of immiscible blends containing CB has, however, not been extensively reported on previously. An immiscible 1:1 blend of PP and PS to which 4 wt% CB was added exhibited a very low melt draw-down ratio at rupture compared wit PP with the same content of CB. By adding 5 wt% SEBS (styrene-ethylene-butene-styrene block copolymer), the ultimate melt draw-down ratio increased about 10 times, which made the material more suitable for melt spinning. As-extruded samples of the immiscible blends (with CB) did not have higher electrical conductivities than PP/CB. A heat treatment increased the conductivity of immiscible PP/PS/CB composites, and longer treatment times and higher temperatures promoted the conductivity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.

  • 26.
    Sun, Fengzhen
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Li, Hu
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Gamstedt, E. Kristofer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Effect of nanosectioning on surface features and stiffness of an amorphous glassy polymer2018In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 58, no 10, p. 1849-1857Article in journal (Refereed)
    Abstract [en]

    Sectioning of a glassy polymer, poly(methyl methacrylate), at nanoscale was carried out by means of an ultramicrotome. The effects of sectioning thickness and speed on the morphology and stiffness over the sectioned surface were then investigated by atomic force microscopy. A critical sectioning thickness and speed were identified, below which flat and smooth surfaces were created with homogeneous elasticity. Above the critical thickness or speed, periodic localized structures formed on the sectioned surfaces, leading to a nonhomogeneous distribution of the mapped elasticity. Finite element simulation reproduced the periodic structures observed in the experiments. The influence of sectioning speed on the surface stiffness was predicted by a phenomenological damage model and was found to correlate with the experimental results. The study lends confidence that critical sectioning conditions (e.g., the sectioning thickness and speed) can be identified to avoid undesirable local deformation and damage in the manufacture of small scale optical and photonic components and devices.

  • 27. Swart, Morne
    et al.
    Olsson, Richard T.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Mallon, Peter E.
    Organic-Inorganic Hybrid Copolymer Fibers and Their Use in Silicone Laminate Composites2010In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 50, no 11, p. 2143-2152Article in journal (Refereed)
    Abstract [en]

    Nonwoven organic-inorganic fiber mats of poly(methyl methacrylate)-graft-poly(dimethyl siloxane) copolymers with various PDMS contents were produced by the electrospinning process. The average fiber diameter increased from 0.7 to 3 mu m with increasing PDMS content. The fiber mats were used in the preparation of silicone-laminated composite materials by distributing them (single, double and triple layer mats) in a silicone matrix prior to thermal curing. The composites showed a remarkably good fiber distribution in the silicone matrix. In general the stiffness and strength increased in the presence of fiber, and surprisingly, so did the toughness/extensibility. An interesting feature was that the most silicon-rich fibers showed clear signs of yielding after tensile testing and failure. This, together with the greater compatibility of the fibers with the matrix because of the higher PDMS content, most probably favored composite toughness. All composite fracture surfaces were characterized by clear signs of fiber pull-out. Fracture initiation areas were difficult to locate, and this is accredited to an even distribution of the individual fibers in the matrix. POLYM. ENG. SC., 50:2143-2152, 2010.

  • 28.
    Toll, Staffan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Packing mechanics of fiber reinforcements1998In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 38, no 8, p. 1337-1350Article in journal (Refereed)
    Abstract [en]

    Theories of fiber packing, of use in manufacturing composite materials, are developed. The maximum packing fraction of force free fibers is estimated based on a statistical analysis of the distribution of fiber-fiber contact points. The new expressions are more general than previous ones by allowing for a distribution in fiber length and orientation. The forced packing beyond this limit is governed by the bending of fiber segments between contact points. A micromechanical theory is developed for this, again based on the contact point statistics, and equations relating the force response per unit area of a fiber bed to the fiber volume fraction are derived for three basic types of assembly: a general 3D wad, a planar mat of dispersed fibers, and a bundle of almost parallel fibers. Other types of reinforcement structure, such as woven fabrics, and the effect of lubrication are also treated briefly.

  • 29.
    Wik, V. M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Aranguren, M. I.
    Mosiewicki, M. A.
    Castor Oil-based Polyurethanes Containing Cellulose Nanocrystals2011In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 51, no 7, p. 1389-1396Article in journal (Refereed)
    Abstract [en]

    Partially foamed and nanocellulose-reinforced polyurethanes (PU) based on castor oil (CO) were prepared and their different properties were measured and related to their structures. A castor oil-based polyol (COPO) was obtained by alcoholysis of CO with triethanolamine. The COPO was used in the preparation of partially foamed and solid PU. Cellulose nanofibrils (NC) in the range of the rheological percolation content were incorporated to the materials and the final mechanical properties of these nanocomposites were analyzed. The incorporated NC considerably affected the rheology of the suspensions, which presented solid-like behavior under frequency sweep tests with the addition of only 0.5 wt% of NC. By increasing the NC concentration the dispersion becomes increasingly difficult. The properties of the solid PU were also affected by the incorporation of NC and a significant increase of the tensile modulus was observed for the 0.5 wt% NC composite, compared to the unfilled solid PU. This behavior was associated to the incorporation of the rigid particle reinforcement and the interfacial bonding. As expected, the partially foamed PU showed lower modulus than the corresponding solid PU.

  • 30.
    Wolter, Nick
    et al.
    University of Bremen, Germany; Fraunhofer, Germany.
    Carrillo Beber, Vinicius
    University of Bremen, Germany; Fraunhofer, Germany.
    Haubold, Thorben
    University of Bremen, Germany; Fraunhofer, Germany.
    Sandinge, Anna
    RISE Research Institutes of Sweden, Safety and Transport, Fire Technology. DTU Technical University of Denmark, Denmark.
    Blomqvist, Per
    RISE Research Institutes of Sweden, Safety and Transport, Fire Technology.
    Goethals, Frederick
    CENTEXBEL, Belgium.
    Van Hove, Marc
    CENTEXBEL, Belgium.
    Jubete, Elena
    BRTA, Spain.
    Mayer, Bernd
    University of Bremen, Germany; Fraunhofer, Germany.
    Koschek, Katharina
    Fraunhofer, Germany.
    Effects of flame-retardant additives on the manufacturing, mechanical, and fire properties of basalt fiber-reinforced polybenzoxazine2021In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 61, no 2, p. 551-561Article in journal (Refereed)
    Abstract [en]

    Basalt fiber-reinforced polybenzoxazines (BFRP) were manufactured through vacuum infusion using resorcinol bis (diphenyl phosphate) and poly-(m-phenylene methylphosphonate) together with bisphenol-F and aniline based benzoxazine. Different types and loadings of flame-retardant additives showed to have catalysis or dilution effects in viscosity measurements. BFRPs show well-penetrated fibers and near-zero porosity. Additive addition did not influence tensile properties, while apparent interlaminar shear strength decreased indicating a lower adhesion between fiber and matrix. BFRP's heat and smoke release properties increased, though time to ignition increased and flammability behavior improved by decreasing delamination yielding oxygen indices in between 72 and 91%. © 2020 The Authors. 

  • 31.
    Zhang, H.
    et al.
    Luleå University of Technology.
    Berglund, Lars A.
    Luleå University of Technology.
    Deformation and fracture of glass bead/CTBN-rubber/epoxy composites1993In: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 33, no 2, p. 100-107Article in journal (Refereed)
    Abstract [en]

    Carboxyl-terminated butadiene-acrylonitrile-rubber decreases modulus and yield stress of the studied epoxy but increases fracture toughness. The addition of glass bead compensates for the loss in modulus but has little effect on yield stress. However, it significantly contributes to the fracture toughness by providing additional mechanisms for toughening of both the unmodified and rubber-modified epoxy. For the toughened epoxies studied, fracture surfaces gave only limited information on fracture mechanisms since significant energy absorption also occurs in the material below the fracture surface. Suggestions for suitable material compositions for fiber composite matrices are given.

1 - 31 of 31
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf