6533b86dfe1ef96bd12ca5c4

RESEARCH PRODUCT

Multifunctional biosourced materials : durability of unidirectional recycled matrix composites reinforced with flax fibers

subject

description

Now more than ever, many engineering sectors are turning to natural fiber composites because of the need for more environmentally friendly solutions. One of the main challenges in developing the use of biocomposites in outdoor applications is the lack of knowledge about their long-term durability. The main objective of this work is to provide a better understanding of the mechanisms involved in photooxidative aging of unidirectional composites made of a virgin or recycled polypropylene matrix, reinforced with long flax fibers. In addition, this work aims to study the potential use of a recycled matrix by comparing the evolution of its behavior to photooxidative aging with a virgin matrix. Thus, accelerated agings and natural weathering under real environmental conditions have been carried out on these materials. The impact of these photooxidative agings on the mechanical and physico-chemical properties of the composites is presented according to a multiscale characterization, from the molecular to the macroscopic scale through the macromolecular and microstructural scales. First, the impact of UV intensity on the photooxidation of the composites was studied. Then, the effect of water spray cycles on the accelerated photooxidative aging was also evaluated. For natural aging, a specific support was set up to decouple the climatic factors in order to better understand the contribution of each factor in the mechanism of photooxidative aging of composites. Based on these photooxidative agings, it has been shown that recycled polypropylene, if it is well selected, can be used as a matrix in natural fiber composites for outdoor applications. Finally, it was found that these materials show a loss of mechanical performance with time which could be improved by a better stabilization of the polymer matrices.