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Bacterial and fungal degradation of wheat straw has become intensively scrutinised in recent years because of the growing interest in procuring useful feedstocks and chemicals from lignocellulosic sources. Typically, after the extraction of valuable sugars and phenolics, significant quantities of solid biomass remain as waste. In this work, it has been shown that the leftover fermented wheat straw can be successfully used to reinforce epoxy resins, providing better strength properties compared to non-degraded straw. A 12% and a 22% increase in Young’s modulus and ultimate tensile strength respectively were observed for degraded wheat straw/epoxy composites compared to composites containing non-degraded straw. The improvement in mechanical strength is explained in terms of the structural and morphological transformations that occurred in the fibres during the fermentation process. The opportunity to use degraded natural fibres in the manufacturing of composites, in addition to the production of chemicals from lignocellulosic feedstocks, looks promising for improving biorefinery economics further.

Composites offer high strength and stiffness at a lower density compared to other structural materials, therefore are of growing use to a variety of lightweight structures in order to reduce emissions and improve performance. However, traditional composites have the highest embodied carbon content of all engineering materials with limited methods of recycling. Therefore moving composites to a biobased sourcing can have a large impact in the eco-footprint of these materials. 2-Methoxy-4-vinylphenol has previously been shown to be sustainably biosourced from microbial degradation of lignin and has been termed ‘biostyrene’. In this work, the authors investigate the use of 2-methoxy-4-vinylphenol analogues as a replacement for styrene as a reactive thinner for thermoset polyester, which is commonly used in fibreglass composite. 2-Methoxy-4-vinylphenyl acetate and 2-methoxy-4-vinylphenyl oleate were synthesised and along with unmodified 2-methoxy-4-vinylphenol and 1,2-dimethoxy-4-vinylbenzene (3,4-dimethoxystyrene) were compared to styrene in typical polyester formulations. The mechanical properties by way of tensile tests and water-uptake tests and thermal properties by way of dynamic scanning calorimetry were used for comparison. Overall, the solubility issues were apparent using the biostyrenes, however, blends of biostyrenes with styrene of up to 50% showed no statistical difference with pure styrene in properties and so may be a viable styrene replacement in polyester used for fibreglass.