The Development of Bio-Based Composite Materials.

Owing to the increasing global population and more widespread industrialisation (particularly with respect to the developing world’s aspirations to equality of standard of living), the extraction and use of materials is expanding. This ever-increasing demand for materials has meant that certain resources are under pressure. Polymer matrix composites, which are normally derived from petrochemicals with synthetic fibres requiring high amounts of energy during manufacture, are increasingly used for both structural and non-structural applications. The development of composites using bio-derived fibres or resins (or both) is an important area of research. This study considers the mechanical properties of various bio-derived fibres, laminated with a range of standard (commercially available) and modified (tailored or with bio-derived content) thermosetting resins, in comparison with synthetic equivalents. The starting point for the current work was to manufacture composites using commonly available natural fibres (hemp, in both chopped strand mat and unidirectional form) with commercial resin systems, primarily to investigate a potential marketing opportunity. This work has shown that it is possible to manufacture such composites, but that their mechanical properties are not particularly useful: in some cases they are in fact worse than the bulk resin. In part this is due to the compatibility of the resin with the fibres. This has been addressed to some extent by the optimisation of the composite with a coupling agent to the formulation. Of more interest however has been the identification of a processed-cellulose fibre, available in a continuous form. Composites made from this have interesting properties and, due to the comparatively low density of the fibres, the specific mechanical properties of the composites are comparable with those of glass based systems. In addition, this study has also conducted an environmental LCA of thermosetting resin manufacture; the conclusions of this have informed the corporate sponsor (Scott Bader) of strategies for reducing the environmental impact of resin manufacture