Replacement of Glass/Unsaturated Polyester Composites by Flax/PLLA Biocomposites: Is It Justified?

Extensive studies on biocomposites are already available in the literature. However the simple fact that they come from renewable resources does not necessarily mean that their environmental impact is lower. The aim of this paper is to quantify the environmental impacts of flax/PLLA biocomposites using a standard life cycle analysis (LCA) in order to evaluate their use as a replacement for glass/unsaturated polyester composites. To fulfil the same mechanical functions under tensile loading and over the life cycle flax/PLLA biocomposites require significantly less non-renewable energy than glass/unsaturated polyester (-97%), while a reduction in climate change (-38%), acidification (-36%), and human toxicity (-85%) are observed. A few indicators are nevertheless higher such as eutrophication (+60%), marine toxicity (+26%) and land use (+98%). Different end-of-life scenarios have been evaluated, including incineration, land-filling, aerobic and anaerobic composting and recycling. Although caution is required, as there is little experience to date, recycling appears to be the most appropriate end-of-life solution because it is top of the waste hierarchy. LCA allows new protocols for material selection to be developed. Two performance indicators are proposed here, which take the consumption of fossil fuels and greenhouse gas emissions into account. The latter are greatly reduced for biocomposites, which further supports their use as a replacement for glass/polyester composites.