EFFECTS OF MATERIAL COMPOSITIONS ON THE CREEP PROPERTIES OF WOOD-PLASTIC COMPOSITES MANUFACTURED BY INJECTION MOLDING

摘要

The objective of this study was to investigate the effects of material compositions on the creep properties of wood-plastic composites(WPCs) manufactured by injection molding. The experimental conditions were used a ratio of plastic matrix (polypropylene, PP and recycled polypropylene, RPP/ wood flour) (30/70, 50/50 and 70/30) and creep load levels (30%, 50% and 70% of MOR). The results are summarized as follows. Under the creep recovery model, creep deflection and creep recovery increase with the increasing of the number of repeat loading times, and their relationships could be expressed by a logarithmic formula. Under the creep load condition of 50% MOR, the instantaneous deflection showed no significant difference between PP50 (plastic/wood flour=50/50) and RPP50. However, it showed remarkably difference of creep deflection followed with the increasing of creep times. The magnitude of relative creep (Rc(t)) for RPP50 WPC were greater than that of PP50 WPC. The magnitude of Rc(t) of different ratio of plastic/wood flour in the following order: RPP30 = RPP 70>RPP50 WPC. Under the creep load condition of 30%, 50% and 70% of MOR: the value of Rc(t) of RPP50 WPC increased with the increasing linearly of creep load levels from 30% to 70% of MOR.