EFFECTS OF ENVIRONMENT ON THE PROPERTIES OF LOW-DENSITY POLYETHYLENE COMPOSITES REINFORCED WITH PINEAPPLE-LEAF FIBER

The influence of water environment on the sorption characteristics of low-density polyethylene composites reinforced with short pineapple-le af fibers (PALF/LDPE) has been studied by immersion in distilled water at 28, 50 and 70 degrees C. The effects of fiber loading, temperature and chemical treatment on the sorption behavior are also evaluated. W ater uptake is found to increase with fiber loading owing to the incre ased cellulose content. Weight change profiles for the composites at h igh temperature indicated that the diffusion is close to Fickian. All of the treated composites showed lower uptake than the unmodified comp osites. Parameters like diffusion, sorption and permeability coefficie nts were determined and activation energies were calculated. The therm odynamic constants such as entropy, enthalpy and first-order kinetic r ate constant have been evaluated. A correlation between theoretical an d experimental sorption results was evaluated. The effect of water upt ake on uniaxial tensile properties has also been studied. Mechanical p roperties decreased after exposure to water, depending on time of imme rsion, fiber loading and chemical treatment. Finally, studies were car ried out on the flexural properties of PALF/LDPE composites exposed to ultraviolet radiation. (C) 1998 Elsevier Science Ltd. All rights rese rved.