This is partly explained by the higher fiber content of the latter (55%) compared to 45% for UD Flax/PLA and UD Flax-paper/PLA, but even when estimating the strength of UD E-glass/Epoxy at 45%, the result (473.5 MPacm3g1
obtained after multiplying the strength by the fiber contents ratio) remains much higher. Fiber treatments to increase the fiber-matrix interfacial adhesion could improve the properties of composite materials and works are currently underway on this [30].