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Manufacture and characterisation of thermoplastic composites made from PLA/hemp co-wrapped hybrid yarn prepregs
University of Borås, School of Engineering. (Polymer Group)
University of Borås, School of Engineering. (Polymer Group)
University of Borås, Swedish School of Textiles. (Polymer Group)
2013 (English)In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840Article in journal (Refereed)
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]

PLA/hemp co-wrapped hybrid yarns were produced by wrapping PLA filaments around a core composed of a 400 twists/m and 25 tex hemp yarn (Cannabis Sativa L) and 18 tex PLA filaments. The hemp content varied between 10 and 45 mass%, and the PLA wrapping density around the core was 150 and 250 turns/metre. Composites were fabricated by compression moulding of 0/90 bidirectional prepregs, and characterised regarding porosity, mechanical strength and thermal properties by dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). Mechanical tests showed that the tensile and flexural strengths of the composites markedly increased with the fibre content, reaching 59.3 and 124.2 MPa when reinforced with 45 mass% fibre, which is approximately 2 and 3.3 times higher compared to neat PLA. Impact strength of the composites decreased initially up to 10 mass% fibre; while higher fibre loading (up to 45 mass%) caused an increase in impact strength up to 26.3 KJ/m2, an improvement of about 2 times higher compared to neat PLA. The composites made from the hybrid yarn with a wrapping density of 250 turns/metre showed improvements in mechanical properties, due to the lower porosity. The fractured surfaces were investigated by scanning electron microscopy to study the fibre/matrix interface.

Place, publisher, year, edition, pages
Elsevier Ltd , 2013.
Keyword [en]
Natural fibre composite, Hybrid yarns, Mechanical testing, Compression moulding, Biocomposites, Resursåtervinning
National Category
Chemical Sciences Polymer Chemistry
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-1560DOI: 10.1016/j.compositesa.2013.03.012ISI: 000320149000011Local ID: 2320/12281OAI: oai:DiVA.org:hb-1560DiVA: diva2:869618
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2015-12-18
In thesis
1. Development of thermoplastic biocomposites based on aligned hybrid yarns for fast composite manufacturing
Open this publication in new window or tab >>Development of thermoplastic biocomposites based on aligned hybrid yarns for fast composite manufacturing
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interest in natural fibres as reinforcement for composite materials has been steadily increasing due to their attractive mechanical properties and the possibility of making more eco-friendly materials. Currently, various alternatives are being introduced for commercial applications, as fibres such as hemp, jute and flax exhibit properties, which make them appropriate for structural composite components. Biocomposites offer reductions in weight and cost and have less reliance on foreign oil resources, making them attractive. Several investigations have revealed that the full utilisation of fibre mechanical properties in the final composites can be exploited, provided an aligned fibre orientation is chosen. In fact, a major challenge for natural fibre reinforced composites is to achieve high mechanical performance at competitive prices. The use of commingled/hybrid yarns is one of the more promising methods for manufacturing structural thermoplastic composites.

Commingled yarns of thermoplastic and reinforcing fibres offer a potential for cost-effective production of composite parts, thanks to reduced applied pressures and impregnation times during processing. Besides economic advantages, there is also direct control over fibre placements and ease of handling of fibres in yarn process. The yarn technologies provide homogenous distribution of reinforcing fibre and matrix. Variation in natural fibre properties has been a major problem facing composite manufacturers, compared to carbon and glass fibres that have well-defined production processes. This issue can be addressed by regenerated cellulose fibres. These fibres can be reproduced easily with high surface evenness and even quality, making it possible to get consistent results, which is not possible with natural fibres. Combination of natural and regenerated cellulose fibre brings together the best of both materials. The end result is a product with superior properties, which could not be obtained by the individual components.

This thesis describes the development of aligned hybrid yarns with low fibre twist, for high performance natural (hemp) and man-made (Lyocell) cellulose fibre-reinforced biocomposites, suitable for use in structural or semi-structural applications. The properties of composites in terms of fibre orientation, off-axis angle and alkali treatment were investigated, focusing on determining void%, water absorption, mechanical and thermo-mechanical properties. The results show that combining hemp and Lyocell in PLA composite leads to the reduction of moisture absorption and can improve the mechanical properties. The mechanical properties of the composites were highly affected by the fibre direction. The alkali treatment on hemp fibre improved the mechanical properties of the composites.

Place, publisher, year, edition, pages
Borås: Högskolan i Borås, 2015. 52 p.
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 74
Keyword
Hybrid yarns, Mechanical properties, Porosity, Weaving, Alkali treatment, Compression moulding
National Category
Textile, Rubber and Polymeric Materials
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-764 (URN)978-91-87525-79-7 (ISBN)978-91-87525-80-3 (ISBN)
Public defence
2015-11-27, D207, Allegatan 1, Borås, 10:00 (English)
Available from: 2015-10-26 Created: 2015-09-15 Last updated: 2015-12-18Bibliographically approved

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Baghaei, BehnazSkrifvars, MikaelBerglin, Lena
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