Micro- and nano-scale mechanisms of enzymatic treatment on the interfacial behaviors of sisal fiber reinforced bio-based epoxy resin

Theoretically, sisal fiber (SF) is an ideal reinforcing material for green composites due to its high specific strength and specific modulus. However, the weak interface performance between SFs and resin affects the mechanical properties of composites. Therefore, the surface modification of SFs was carried out by enzymatic treatment to enhance the interfacial properties between SFs and bio-based epoxy resin in this work. It was found that the interfacial strength was effectively increased by 108% after the SF was treated with xylanase and pectinase for 6 h. The experiment study showed that the enzymatic treatment mainly caused the hydrolysis and cleavage of pectin and hemicellulose of SFs, which increased the surface grooves and surface roughness of SFs. The further finite element analysis proved that the mechanical interlocking effect at the nano-scale induced by surface roughness of SFs was the primary reason for the increase of interfacial strength between SFs and bio-based epoxy resin. Enzymatic treatment provides a green and large-scale production method for interface modification of SFs reinforced composites, which also can be used for the other bast fiber reinforced composites.