Mechanical Properties of Polypropylene Composites Based on Natural Fibers Subjected to Multiple Extrusion Cycles

JUAN MORÁN; VERA ALVAREZ; ANALÍA VÁZQUEZ

Buenos Aires - Argentina

Congreso; International Conference on Science and Technology of Composite Materials, COMAT 2005; 2005

In this work, the feasibility of re-use of composite materials based on polypropylene and natural fibers was studied. Composites with 20% (weight fraction) of flax fibers were prepared. The composite was obtained by twin screw extrusion. The recycling process was simulated applying multiple extrusion steps. In order to characterize the resulting materials, compression molded plates were made. Melt flow index studies showed that an important degradation takes place on the polypropylene matrix during sequent extrusion cycles. Similar mechanical behaviour was observed in all tests, showing an improvement of mechanical properties by increasing extrusion cycles. This effect is due to better mixing of the fibres into the matrix (distribution and dispersion). Young’s modulus was correlated by using a modified Halpin – Tsai model. Elastic modulus of the reinforcement was considered to vary according to Grifith’s modelto take into account the mechanical degradation suffered by the fibres. It was observed a good correlation was obtained by applyingthe Halpin-Tsai model including the both corrections (Grifith`s model and correction factors as well).