Interface modification on the properties of sisal fiber-reinforced polypropylene composites

Short sisal fiber (SF)-reinforced polypropylene (PP) composites were prepared by melt blending followed by injection molding. To improve the interfacial bonding between SF and PP, the PP matrix was maleated (MAPP) by blending PP and maleic-anhydride-grafted-PP in the weight ratio of 9/1. It was found that the SF/MAPP composites have lower melt viscosity (as reflected by torque rheometer measurements) than the SF/PP composites at the respective sisal fiber contents. In terms of mechanical properties, PP maleation has the effect of improving the tensile strength. This can be explained in terms of the improved SF/matrix interfacial bonding when MAPP was used. However, the impact strength was reduced when the PP matrix was maleated. The improved SF/matrix interfacial bonding prevented fracture mechanisms such fiber/matrix debonding and fiber pullout from taking place.