Composites utilizing vegetable fibers as reinforcement have demonstrated attracted increasing interest ofcrescent advantages from the scientific and industrial communities. Sugarcane bagasse and straw are renewable materials and when used as reinforcement in thermoplastic matrix can give origin to composite materials with low cost, low density and interesting mechanical properties. This work aimed to evaluate the mechanical and morphological properties of polypropylene composites reinforced with cellulose from sugarcane bagasse and straw. The cellulose was obtained through NaOH/AQ pulping process at 170ºC for 3.5 h. The composites reinforced with 20 and 30 % wt of fibers were preparated utilizing a Dryser mixer. After ground and injection molding, these materials were analyzed by tensile and flexural tests, optical microscopy (OM) and scanning electron microscopy (SEM). The tensile strength of composites reinforced with fibers (20 wt.%) was similar to that of pure polypropylene, however, it decreased with the increase increasing amount of reinforcement. The tensile and flexural elasticity moduli increased up to 79.4 and 81.7 %, respectively, due to the high modulus of the fibers inserted inside the polymeric matrix. The composite surface analysis by OM showed homogeneous distribution of fibers inside the matrix and variable length and shape of the fibers. The cellulosic fibers from straw were also smaller than those from bagasse. SEM analysis of fractured composites exhibited pullout displacement of the fiber in with respect to thematrix and a typical behavior of brittle fracture. Cellulosic fibers obtained from sugarcane bagasse and straw resulted in composites with similar mechanical and morphological properties and provided rigidity to thematrix.
cellulose; sugarcane bagasse and straw; polypropylene; composites; morphology
