Sisal fibre/polypropylene composites modified with carboxyl terminated hyperbranched polymer

In this study, polypropylene (PP)/sisal fibre (SF)/carboxyl terminated hyperbranched polymer (CTHP) composites were prepared by using short SF as the reinforcement, PP as the matrix and CTHP as a compatiliser. The impact fracture surface of PP/SF composites and the interfacial compatibility between PP and SF were analysed. Experimental results showed that the impact strength and flexural strength of PP/SF composites modified with the CTHP (2 wt-% of SF) were 21.5 and 9.7% higher than that of unmodified systems respectively. The SEM photomicrographs of the fracture surfaces have also shown that PP was highly bonded to the SF in the CTHP treated composites; wide angle X-ray diffraction (WAXD) measurement indicated that the CTHP did not change the crystal structure of PP and was still a-type crystal. Moreover, the addition of a small amount of the CTHP was helpful to improve water resistance of SF/LGF/PP composites.