Short term flexural creep behavior of wood-fiber/polypropylene composites

Short term flexural creep tests were conducted to investigate the creep 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 terms 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 stress, but had little effect at a lower stress level. The extent of relative creep increased with increasing temperature. It was found that the slope of the power law model was directly proportional to the temperature. The addition of wood-fibers into pure polymer greatly improved the creep resistance of the matrix polymer. The relative creep of the composites decreased with an increase in wood-fiber concentration. However, 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. The flexural modulus of the composites also had an inverse relationship with the time exponent.