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Biocomposites can be both environmentally and economically beneficial: during their life cycle they generally use and generate less petroleum-based carbon, and when produced from the byproduct of another industry or recycled back to the manufacturing process, they will bring additional economic benefits through contributing to a circular economy. Here we investigate and compare the environmental performance of a biocomposite composed of a soybean oil-based resin (epoxidized sucrose soyate) and flax-based reinforcement using life cycle assessment (LCA) methodology. We evaluate the main environmental impacts that are generated during the production of the bio-based resin used in the biocomposite, as well as the biocomposite itself. We compare the life cycle impacts of the proposed biocomposite to a functionally similar petroleum-based resin and flax fiber reinforced composite, to identify tradeoffs between the environmental performance of the two products. We demonstrate that the bio-based resin (epoxidized sucrose soyate) compared to a conventional (bisphenol A-based) resin shows lower negative environmental impacts in most studied categories. When comparing the biocomposite to the fossil fuel derived composite, it is demonstrated that using epoxidized sucrose soyate versus a bisphenol A (BPA)-based epoxy resin can improve the environmental performance of the composite in most categories except eutrophication and ozone layer depletion. For future designs, considering an alternative cross-linker to facilitate the bond between the bio-based resin and the flax fiber, may help improve the overall environmental performance of the biocomposite. An uncertainty analysis was also performed to evaluate the effect of variation in LCA model inputs on the environmental results for both the biocomposite and composite. The findings show a better overall carbon footprint for the biocomposite compared to the BPA-based composite at almost all times, demonstrating a good potential for marketability especially in the presence of incentives or regulations that address reducing the carbon intensity of products. This analysis allowed us to pinpoint hotspots in the biocomposite's supply chain and recommend future modifications to improve the product's sustainability. [ABSTRACT FROM AUTHOR]

Today, plant fibers are considered as an important new renewable resource that can compete with some synthetic fibers, such as glass, in fiber-reinforced composites. In previous works, it was noted that the pectin-enriched middle lamella (ML) is a weak point in the fiber bundles for plant fiber-reinforced composites. ML is strongly bonded to the primary walls of the cells to form a complex layer called the compound middle lamella (CML). In a composite, cracks preferentially propagate along and through this layer when a mechanical loading is applied. In this work, middle lamellae of several plant fibers of different origin (flax, hemp, jute, kenaf, nettle, and date palm leaf sheath), among the most used for composite reinforcement, are investigated by atomic force microscopy (AFM). The peak-force quantitative nanomechanical property mapping (PF-QNM) mode is used in order to estimate the indentation modulus of this layer. AFM PF-QNM confirmed its potential and suitability to mechanically characterize and compare the stiffness of small areas at the micro and nanoscale level, such as plant cell walls and middle lamellae. Our results suggest that the mean indentation modulus of ML is in the range from 6 GPa (date palm leaf sheath) to 16 GPa (hemp), depending on the plant considered. Moreover, local cell-wall layer architectures were finely evidenced and described. [ABSTRACT FROM AUTHOR]