Realization of Polypropylene/Sisal Fiber Composites by Reactive Extrusion

Sisal fibers are used for the reinforcement of a polypropylene matrix. The compatibilization between the two materials is assumed through treatment of cellulosic fibers with a maleated polypropylene (PP-graft-MA). The influence of different parameters is studied: fibers fraction, washing of raw fibers, chemical treatment of the fibers in a solvent or during extrusion, rate of maleic anhydride in PP-graft-MA and the rate of PP-graft-MA in the composites. The effects of these parameters are evaluated by determination of the mechanical properties of the composites (impact strength and breaking stress) and by the quantity of water sorbed by the composites. The elimination of pectic substances by washing of the fibers is favorable for the mechanical properties of the composites and also reduces their water sorption. The grafting of the fibers by PP-graft-MA enhances both the impact strength and the breaking stress.