Study on jute twine/polypropylene pre-preg tapes: The effects of surface modification and impregnation

Abstract

Preparation of natural fiber-reinforced thermoplastic prepreg tapes is impeded by two major challenges: 1) incompatibility between natural fibers and thermoplastic; and 2) difficulty impregnating thermoplastic into fibers, due to thermoplastics’ high viscidity. In this study, we investigated the reaction mechanisms associated with jute twines that were treated with alkali and laccase, to improve the compatibility of jute twine/ polypropylene (PP) tape. Simultaneously, PP with three melt flow indices (MFI, 10.9 g/10 min, 27.8 g/10 min, 50.0 g/10 min) was tested to determine optimal conditions for PP impregnation. The results showed that alkali and laccase treatment can effectively improve the interfacial bonding strength between jute twine and PP; although laccase treatment is milder than alkali treatment, and thus enabled more improvement in the prepreg tapes’ tensile and dynamic mechanical properties. The amount of PP impregnated into the jute twine increased as a function of increasing MFI. However, the impregnation effect must be balanced with the PP’s tensile strength. In summary, the prepreg tapes prepared by laccase-treated jute twine and PP with an MFI of 27.8 g/10 min exhibited the best tensile performance. Based on subsequent calculations, the nominal pressure of a pipe wound with laccase-modified jute twine prepreg tapes, can reach 2.88 MPa.