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Development of thermoplastic biocomposites based on aligned hybrid yarns for fast composite manufacturing
Högskolan i Borås, Akademin för textil, teknik och ekonomi.
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Hållbar utveckling
Innehållet faller inom området hållbar samhällsutveckling
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.

Ort, förlag, år, upplaga, sidor
Borås: Högskolan i Borås, 2015. , s. 52
Serie
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 74
Nyckelord [en]
Hybrid yarns, Mechanical properties, Porosity, Weaving, Alkali treatment, Compression moulding
Nationell ämneskategori
Textil-, gummi- och polymermaterial
Forskningsämne
Resursåtervinning
Identifikatorer
URN: urn:nbn:se:hb:diva-764ISBN: 978-91-87525-79-7 (tryckt)ISBN: 978-91-87525-80-3 (tryckt)OAI: oai:DiVA.org:hb-764DiVA, id: diva2:854028
Disputation
2015-11-27, D207, Allegatan 1, Borås, 10:00 (Engelska)
Tillgänglig från: 2015-10-26 Skapad: 2015-09-15 Senast uppdaterad: 2015-12-18Bibliografiskt granskad
Delarbeten
1. Characterization of thermoplastic natural fibre composites made from woven hybrid yarn prepregs with different weave pattern
Öppna denna publikation i ny flik eller fönster >>Characterization of thermoplastic natural fibre composites made from woven hybrid yarn prepregs with different weave pattern
2015 (Engelska)Ingår i: Composites Part A: Applied Science and Manufacturing, Vol. 81, nr February 2016, s. 139-144Artikel i tidskrift (Övrigt vetenskapligt) Published
Nyckelord
A. Fabrics/textiles B. Mechanical properties E. Weaving E. Compression moulding
Nationell ämneskategori
Teknik och teknologier
Forskningsämne
Resursåtervinning
Identifikatorer
urn:nbn:se:hb:diva-3991 (URN)10.1016/j.compositesa.2015.10.042 (DOI)
Tillgänglig från: 2015-12-10 Skapad: 2015-12-10 Senast uppdaterad: 2018-06-01Bibliografiskt granskad
2. Manufacture and characterisation of thermoplastic composites made from PLA/hemp co-wrapped hybrid yarn prepregs
Öppna denna publikation i ny flik eller fönster >>Manufacture and characterisation of thermoplastic composites made from PLA/hemp co-wrapped hybrid yarn prepregs
2013 (Engelska)Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 50, s. 93-101Artikel i tidskrift (Refereegranskat) Published
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.

Ort, förlag, år, upplaga, sidor
Elsevier Ltd, 2013
Nyckelord
Natural fibre composite, Hybrid yarns, Mechanical testing, Compression moulding, Biocomposites, Resursåtervinning
Nationell ämneskategori
Kemi Polymerkemi
Forskningsämne
Resursåtervinning
Identifikatorer
urn:nbn:se:hb:diva-1560 (URN)10.1016/j.compositesa.2013.03.012 (DOI)000320149000011 ()2320/12281 (Lokalt ID)2320/12281 (Arkivnummer)2320/12281 (OAI)
Tillgänglig från: 2015-11-13 Skapad: 2015-11-13 Senast uppdaterad: 2017-11-02Bibliografiskt granskad
3. Novel aligned hemp fibre reinforcement for structural biocomposites: Porosity, water absorption, mechanical performances and viscoelastic behaviour
Öppna denna publikation i ny flik eller fönster >>Novel aligned hemp fibre reinforcement for structural biocomposites: Porosity, water absorption, mechanical performances and viscoelastic behaviour
Visa övriga...
2014 (Engelska)Ingår i: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 61, s. 1-12Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

This paper examines the thermal and mechanical behaviour as well as moisture absorption of aligned hemp composites using hemp/PLA wrap spun yarns. Uniaxial composites were fabricated with 30 mass% hemp using compression moulding. The properties of composites in terms of hemp fibre orientation (aligned and random), off-axis angle and alkali treatment were investigated. It was found that the testing direction influenced the mechanical properties of the composites. Compared with all the fabricated composites, the aligned alkali hemp/PLA yarn composite possessed the best mechanical properties, including tensile, flexural and impact strengths, lower porosity and water absorption. The water absorption for all composites was higher than for neat PLA, both at room temperature and 80 C. The PLA in its treated composites had higher crystallinity, which was attributed to effective heterogeneous nucleation induced by hemp. Based on SEM observation and theoretical analysis of DMTA data, there was a favourable interfacial adhesion in all composites.

Ort, förlag, år, upplaga, sidor
Elsevier, 2014
Nyckelord
Fabrics/textiles, Mechanical properties, Porosity, Compression moulding, Resource recovery
Nationell ämneskategori
Kemi
Forskningsämne
Resursåtervinning
Identifikatorer
urn:nbn:se:hb:diva-1835 (URN)10.1016/j.compositesa.2014.01.017 (DOI)000335104100001 ()2320/13548 (Lokalt ID)2320/13548 (Arkivnummer)2320/13548 (OAI)
Tillgänglig från: 2015-11-13 Skapad: 2015-11-13 Senast uppdaterad: 2017-11-02Bibliografiskt granskad

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