EFFECT OF ALKALI TREATMENT AND MAPP ADDITION ON TENSILE STRENGTH OF SISAL/POLYPROPYLENE COMPOSITES

Mechanical properties of composite are strongly influenced by surface treatment of fibers and fiber content. The study aimed to verify the influence of a modified fiber surface using an alkali solution and, the addition of maleic anhydride grafted polypropylene (MAPP) and both (alkali solution + MAPP) on increasing the tensile strength of sisal/polypropylene (PP) composites. The composites were fabricated using hot compression molding with a fiber content of 30 and 50 wt%. Untreated and alkali-treated sisal fibers with a fiber length of ~ 2 mm were used. Various amounts (5, 10 and 15 wt%) of MAPP were added to the untreated sisal/PP and alkali-treated sisal/PP composites. The results indicated that the tensile strength of the untreated sisal/PP composite containing 50 wt% of fiber was higher than that of 30 wt% fiber content. The addition of 5 wt% MAPP into both untreated and alkali-treated sisal/PP composites significantly increased tensile strength compared to that of 10 and 15 wt% MAPP addition. Good interfacial bonding between sisal fiber and the PP matrix was observed at 5 wt% MAPP loading. Excessive MAPP content could form a barrier that tends to inhibit the stress transferred across the matrix-fiber interfaces