Replacing styrene with bioderived alternatives in polyesters

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.