Flexural behaviour and damage extent in woven natural fibres/polypropylene composite laminates

Recently, low environmental impact and potential use in a wide range of applications have been the main driving reasons supporting the rapid growth of the research interest toward the investigation and development of items based on natural fiber composites. This paper compares the performance and the extent of damage suffered by polypropylene (PP) composites reinforced with natural fiber fabrics and subjected to flexural loads. In particular, laminates including jute, flax and basalt woven fibers have been prepared by typical film stacking and compression molding techniques. A premodified matrix (PPC) including 2 wt% of a coupling agent was also considered. Measurements were carried out on at least 5 determinations for each kind of samples. All flexural parameters appeared to be significantly increased for specimens based on PPC with respect to the ones based on neat PP with effects particularly pronounced in presence of basalt fibers. Despite the use of the same content of coupling agent, this finding can be attributed the achievement of a different extent of interfacial adhesion, in turn, due to the different nature of reinforcing fibers. The influence of both the matrix modification and the nature of reinforcing fibers on the extent of induced flexural damage were assessed in non-destructive way by Electronic Speckle Pattern Interferometry and by Scanning Electron Microscopy observations of cryofractured surfaces.