Study On The Mechanical Strength And Visco-elastic Behavior Of WPC Including Temperature Effects

As a new kind of material, the WPC (Wood and Plastic Composite) has absorbed more and more attention from people. But the impediment to utilize these materials is the lack of comprehension about the performance of WPC. In environment, the performance of these materials is affected by the high temperature obviously. Three aspects are included in this paper, the first interest for this study is the static flexural strength,creep,stress relaxation of the different kinds of WPC under different temperatures, another focus of this work is to gain the long-term creep performance of the WPC by using the short-term creep testing procedure and the TTSP(Time Temperature Superposition Principle),TTSSP(Time Temperature Stress Superposition Principle), and the last aspect is the effect of temperature on the aging of WPC. We can reach the conclusion after analyzing the experimental test results:1 In a lot of environmental factors, the temperature is one of important factors that can affect WPC, the mean max stress value of HDPE/rice husk flour WPC at the 85℃was reduced to 44.54% of that at the 35℃, the mean max stress value of PP/wood fiber WPC at the 75℃was reduced to 33.93% of that at the 35℃, the mean max stress value of new HDPE/ Moso Bamboo fiber,recycled HDPE/ Moso Bamboo fiber,recycled HDPE/ Small-Diameter Bamboo fiber WPC at the 85℃were reduced to 40.06%,46.27%,35.87% of those at the 35℃respectively. We also can find that the WPC which comprises the HDPE is affected by the temperature less, because the glass transition temperature of HDPE WPC is about 140℃, but that of PP WPC is only 90℃.2 Creep behavior of WPC is strongly dependent on the amount of stress, time and temperature. The WPC has the characters of the simple thermo-rheologic materials. There are three parts are included in the short-term creep curve: elastic phase,visco-elastic phase and viscous phase. We can utilize the TTSP,TTSSP to predict the long-term creep performance ,then get the mechanic models and the mathematics formula.3 The flexural strength of the WPC decrease dramatically during the 12 hours, and then increase a little between 12 and 122 hours, but it does not change much after 122 hours. The glass transition temperature of the WPC does not change after about 1000 hours under high temperature.