CP5_FF_PP has poor wetting of polypropylene across the fibre layers as indicated by the dry fibre without any polymer in the opening of the delaminated piece (see Fig. 5b).CP5_FF_PP failed
because of insufficient matrix to transmit the load sharing among neighboring fibers. When placed over a bright light source, the cracks present on both unidirectional flax reinforced polymer
composite (i.e., UD4_FF_EP and UD1_FF_PP) run along the interfacial bonding between the flax fibers and the epoxy resin (see Fig. 6a and c).