Natural fibre-polyhydroxyalkanoate PHA composites

As a result of past research on PHAs and the commercial development of PHB and PHBV, it is perhaps not surprising that these polymers have also been examined for use in biodegradable composites. Examples of reinforcing fibres used with PHAs have included wood (Reinsch and Kelley, 1997 Peterson et al, 2002), wheat straw (Avella et al, 2000a, 2000b), pineapple leaf fibres (Luo and Netravali, 1999) and jute (Khan et al, 1999) amongst others. 

The idea of treating jute fibres with different additives to enhance the properties of hot-pressed Biopol composites was examined by Khan et al. (1999). As in a number of other research studies, Biopol , a PHBV originally developed by ICI but now owned by Metabolix Inc of the US, was the chosen polymer matrix. Jute was used in the form of a fabric combined with sheets of polymer film. Fibre treatments included 2-ethyl hexyl acrylate (3%), 7-methacryloxypropyltrimethoxysilane (2%) and trimethoxyvinylsilane (0.5%). These treatments were effective in improving composite mechanical properties by up to 80% over and above those properties obtained when using untreated fibre. 

2 Schematic of the process for making natural fibre (e.g., jute)-PLA composites using a film-stacking method (source Plackett eta ., 2003). 

3 Mechanical properties of PHB and jute-PHB composites processed at various temperatures (source Plackettand Andersen, 2002). 

Flax-PHB composites have been prepared by mixing flax fibres with a chloroform solution of PHB (Shanks et al., 2004). The solvent was allowed to 

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