Hygrothermal aging and tensile behavior of injection-molded rice husk-filled polypropylene composites

The effect of the filler volume fraction on the tensile behavior of injecti on-molded rice husk-filled polypropylene (RH-PP) composites was studied. Hy grothermal aging behavior was also investigated by immersing the specimens in distilled water at 30 and 90 degreesC. The kinetics of moisture absorpti on was studied from the amount of water uptake by specimens at regular inte rval times. It was found that the diffusion coefficient and the maximum moi sture content are dependent on the filler volume fraction and the immersion temperatures. Incorporation of RH into the PP matrix has led to a signific ant improvement in the tensile modulus and a moderate improvement in the te nsile strength. Elongation at break and energy at break, on the other hand, decreased drastically with the incorporation of the RH filler. The extent of deterioration incurred by hydrothermal aging was dependent on the immers ion temperature. Both the tensile strength and tensile modulus deteriorated as a result of the combined effect of thermal aging and moisture attack. F urthermore, the tensile properties were not recovered upon redrying of the specimens. Scanning electron microscopy was used to investigate the mode of failure of the RH-PP composites. (C) 2001 John Wiley & Sons, Inc.