Natural Fibre Composites with 3D Woven Reinforcement for New Application Areas

Abstract

The cross-discipline research embodied in this paper is a culmination of substantial research advancing the field of natural fibre reinforced composites. This international peer reviewed paper was selected for its pioneering approach to developing sustainable woven composite materials. Contributors in this issue were selected from high profile experts that tackle issues on ‘Materials for a Low Carbon Future’ presented at the Natural Fibres ‘09 Conference in Dec 2009 at The Institute of Materials, London. Materials that contribute to a prominent environmental agenda were presented, such as composite materials made from natural plant-based fibres as an alternative to synthetic petroleum based fibres. The author gave a keynote address at this conference. The research determines the fabrics initial mechanical properties against standard fabric benchmarks. It highlights technical trade-off’s between old materials that fail in a familiar way and new materials that combat these failure mechanisms but fall slightly short (in certain tests) on enhanced properties. The work establishes both benefits and production challenges these materials face en-route to commercialisation and wider acceptance. Published by Elsevier (USA), the Journal special issue featured International research from global experts who were working at various 'technology-readiness levels' to generate data and future products. The paper was also a key outcome of AHRC project 3D Reinforced Natural Fibre Reinforced Woven Preforms and Eco-composites’ (AH/E007953/1)). Spin-off benefits from this publication included future collaborations with the technical textile Industry in the UK and with natural fibre composite experts. PUBLISHED ABSTRACT: The cross-discipline research embodied in this paper has been generated from a technical textile design perspective, where the author, as an established technical weave designer, has developed 3D woven natural fibre preforms for composite production and subsequent testing. This research is a comparative study between commercially available 2D bi-axial woven plied composite laminate and 3D reinforced woven multiple layer composites using both flax and naturally derived viscose yarns for natural fibre composite applications. The objective is to determine the initial properties of two natural fibre 3D woven composites with relatively low fibre volume fraction and assess their performance against a standard natural fibre 2D woven fabric lay-up arrangement. In order to achieve this, the textile design and production cycle must be considered. The paper focuses on the design and assemblage of 3D woven textile preforms, discussing the complex design parameters associated with obtaining desired loom state fibre volume fractions within the 3D material. It also highlights the weave production issues that impact on the quality and integrity of 3D woven fabric architectures for flat and tailored reinforcements. Treatment experiments with 4% NaOH on flax yarns were attempted to establish if the woven fabrics would benefit from post-production treatment prior to resin processing to improve interfacial bonds between fibres and matrix. Once woven, it details the Vacuum Assisted Resin Transfer Moulding (VARTM) processing method using epoxy resin and presents initial results from mechanical test programs assessing flexural strength and damage resistance. By selecting a 2D 2/2 woven twill laminate and angle interlock (AI) 3D architecture as baseline control samples, an early assessment will establish the benefits and challenges these materials face, and their future potential. Findings from the research indicated that 2D twill flax composites achieve a higher fibre volume fraction which, in turn, leads to superior flexural properties with respect to 3D AI composites. 2D 2/2 twill viscose rayon composites flexural strength and modulus were found to be superior to 3D angle interlock structures but inferior in damage resistance. The damage characteristics from impact resistance tests show differences in damage area, impact depths and the dispersal of subsidiary cracking. Test specimens demonstrate that 3D woven viscose rayon composites displayed mostly localized damage around the location and did not allow the damage to radiate out substantially which is in contrast to the delamination damage observed in the 2D material. From this publication the author was invited to be a member of the International Organising Committee for conference “Emerging Green Technologies”, the Annual Environmental Biopolymer Society (BEPS) in USA, held in Toronto, Oct 2010 and member of the organising committee for the ECOCOMP conferences in the UK (2013). Keywords: WOVEN; PREFORM; NATURAL FIBRE COMPOSITES; VACUUM ASSISTED RESIN TRANSFER MOULDING (VARTM)Document Type: Research article DOI: 10.1166/jbmb.2010.1078