Effect of Coupling Agent Content and Water Absorption on the Mechanical Properties of Coir-Agave Fibers-Reinforced Polyethylene Hybrid Composites

In this study, high-density polyethylene/agave-coir composites with two fiber contents (20 and 30 wt%) and different coir-agave fiber ratios (1-0, 0.8-0.2, 0.60.4, 0.4-0.6, 0.2-0.8, and 0-1) were produced in a two-step process using twin-screw extrusion followed by injection molding. The effect of mixing two different natural fibers and the addition of coupling agent on water absorption, mechanical properties, and morphology is reported. The rule of hybrid mixture was used to predict the properties of the composites, showing a good agreement with the experimental data. The results obtained showed that the combination of different fibers produces composites with unique characteristics as coir fibers absorb less water than agave fibers, while at the same time increase more tensile and flexural strengths. On the other hand, agave fibers were found to improve the impact strength of coir composites. Also, the effect of water absorption on the mechanical properties was studied. Finally, the use of a coupling agent had a positive effect on mechanical properties, while lowering water uptake. (C) 2015 Society of Plastics Engineers