A Study of the Short-Term Flexural Creep - Recovery Behaviour of Rice Hull Flour/HDPE Composites

In this study the short – term flexural creep-recovery of rice hull flour / HDPE (high density polyethylene) composites were investigated. The rice hull flour / HDPE composites were manufactured by using a dry blend/ hot press method. In this method the powder of HDPE (virgin, recycled and mixed of them) and dried flour of rice Hull were mixed in proportion to 60% of the loading weight in an experimental mixer with 1500 rounds per minute in five minutes. Speciment panels with the sizes of 35×35×1 cm were manufactured from the obtained mixtures by using the hot pressure at 190 oc. The nominal density of panels was 1 gr/cm3. In order to study the short-term flexural creep – recovery behaviour of composites, the flexural speciments were pressed at 10, 20 and 30 percent of maximum bending load and held constant during the test. The displacements in midpoint of speciments were measured with an extensometer during creep-recovery time. The total times were 60 minutes (30 minutes for creep and 30 for recovery). The results indicated that the creep – recovery behaviour of the composites was affected by the type of HDPE, and load levels. The behaviour of composites was obviously non-linear at higher levels of load. The most permanent recovery in the composites of rice hull flour/ HDPE was observed in the high levels of load. The results also revealed that the creep behaviour in rice hull flour/HDPE followed the Findley power law.