SHORT-TERM FLEXURAL CREEP-BEHAVIOR OF WOOD-FIBER POLYPROPYLENE COMPOSITES/

Short term flexural creep tests were conducted to investigate the cree p behavior of wood-fiber polypropylene composites. Three experimental parameters were selected: the addition of a wetting agent, temperature , and wood-fiber concentration. All creep curves are presented in term s of relative creep as a percentage of instantaneous (initial) strain. The creep power law model was used to accurately fit the creep data. The addition of a wetting agent greatly reduced the creep at high stre ss, but had little effect at a lower stress level. The extent of relat ive creep increased with increasing temperature. It was found that the slope of the power law model was directly proportional to the tempera ture. The addition of wood-fibers into pure polymer greatly improved t he creep resistance of the matrix polymer. The relative creep of the c omposites decreased with an increase in wood-fiber concentration. Howe ver, the composite showed relatively large creep compared with that of solid wood. It was found that both the time exponent and slope of the power law model were inversely related to wood-fiber concentration. T he flexural modulus of the composites also had an inverse relationship with the time exponent.