| 1. |
- Andersons, J., et al.
(författare)
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Statistical model of coating fragmentation under equibiaxial load
- 1998
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Ingår i: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 13:4, s. 597-602
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Tidskriftsartikel (refereegranskat)abstract
- A statistical model of coating cracking under equibiaxial tension is proposed based on a Weibull strength distribution for the coating. Crack length and spacing distributions are derived assuming that cracks initiate in random locations and propagate straight till stopping upon encountering a geometiical obstacle (another crack). The theoretical distributions are verified by comparing with simulated cracking patterns obtained by the Monte-Carlo method. An analysis of crack patterns of SiO2 coatings on a PET film under biaxial tension is performed. Qualitative agreement with the theoretical crack spacing distribution is observed.
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| 2. |
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| 3. |
- Lundquist, L., et al.
(författare)
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Alkali-methanol-anthraquinone pulping of Miscanthus x giganteus for thermoplastic composite reinforcement
- 2004
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 92:4, s. 2132-2143
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Tidskriftsartikel (refereegranskat)abstract
- The potential of pulp fiber-reinforced thermoplastics is currently not fully explored in composites. One of the main reasons is that pulp fibers are extracted for the use in papermaking and are thus not optimized for use as reinforcements in thermoplastics. Furthermore, currently used processing methods constitute several severe thermomechanical steps inducing premature degradation of the fibers. A systematic development of these composite materials requires the study of both these aspects. The goal of this work was to optimize fiber extraction against properties relevant to the reinforcement of thermoplastics. To this end, thick-walled Miscanthus x giganteus pulp fibers were selected. The fibers were pulped by the alkaline-methanol-anthraquinone process. An unreplicated factorial design was applied to determine the effect of key operating variables on fiber thermal stability and mechanical properties. The thermomechanical properties of pulp fibers depend primarily on the morphology and chemical composition of the fiber resource in terms of the respective amounts of lignin, hemicellulose, and cellulose, all strongly influenced by the choice of pulping conditions. Optimal pulping parameters were identified, allowing production of fibers thermally stable up to 255 degreesC with an aspect ratio of 40, a straightness of 95%, and tensile strength as high as 890 MPa. Specific stiffness and strength values with respect to density and material cost of 56 GPa m(-3) $(-1) and 820 MPa m(-3) $(-1) were highly competitive with glass fibers, with corresponding values of 15 GPa m(-3) $(-1) and 270-490 MPa m(-3) $(-1), respectively.
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| 4. |
- Plummer, C. J. G., et al.
(författare)
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Influence of processing routes on morphology and low strain stiffness of polymer/nanofibrillated cellulose composites
- 2015
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Ingår i: Plastics, rubber and composites. - 1465-8011 .- 1743-2898. ; 44:3, s. 81-86
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Tidskriftsartikel (refereegranskat)abstract
- The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively homogeneous NFC dispersions and significant reinforcement of the in-plane Young's modulus. The continuous cellular networks obtained by wet comingling of polylactide powder or latex with NFC also provided efficient and essentially scale independent reinforcement, in spite of the extensive agglomeration of the NFC. However, the irreversible nature of these networks is incompatible with low pressure thermoplastic processing routes such as physical foaming, and while they may be broken up by e.g. extrusion, this led to substantial loss in reinforcement, particularly at temperatures above the glass transition temperature of the matrix, consistent with the observation of isolated low aspect ratio NFC aggregates in the extruded specimens.
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| 5. |
- Plummer, C. J. G., et al.
(författare)
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Influence of processing routes on the morphology and properties of polymer/nanofibrillated cellulose composites
- 2014
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Ingår i: 16th European Conference on Composite Materials, ECCM 2014. - 9780000000002
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Konferensbidrag (refereegranskat)abstract
- The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively homogeneous NFC dispersions and significant reinforcement of the in-plane Young's modulus. The continuous cellular networks obtained by wet-comingling of PLA powder or latex with NFC also provided efficient and essentially scale-independent reinforcement, in spite of the extensive agglomeration of the NFC. However, the irreversible nature of these networks is incompatible with low pressure thermoplastic processing routes such as physical foaming, and while they may be broken up by e.g. extrusion, this led to substantial loss in reinforcement, particularly above Tg, consistent with the observation of isolated low aspect ratio NFC aggregates in the extruded specimens.
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