木纤维含量对木塑复合材料蠕变特性的影响

Influence of Wood Fiber Content on the Creep Behavior of Wood Fiber-Plastic Composite

测试了不同木纤维含量(质量分数)的木塑复合材料的24h蠕变应变和24h回复应变,分析了木纤维含量对木塑复合材料蠕变特性的影响,并采用十元件广义Kelvin模型和Findley幂律模型对木塑复合材料24h蠕变曲线进行了拟合.测试分析了温度对木塑复合材料蠕变特性的影响.结果表明:在各测试条件下增加木纤维含量都有助于提高木塑复合材料的抗蠕变应变能力.当木纤维含量由50%增加到70%时,木塑复合材料的弯曲强度和弹性模量显著升高,24h蠕变应变减小了58%左右;当木纤维含量由50%增加到70%时,木塑复合材料回复应变差别没有蠕变应变差别那么显著.在10%和20%加载应力水平下,50%与60%木纤维含量的木塑复合材料24h蠕变回复率接近,而在30%加载水平下,60%和70%木纤维含量的木塑复合材料24h蠕变回复率接近.十元件广义Kelvin模型和Findley幂律模型均可较好地拟合木塑复合材料的24h蠕变曲线.温度升高使木塑复合材料的蠕变应变增大;在一定温度范围内增加木纤维含量有利于抑制木塑复合材料的蠕变应变.

24 h creep strains and recovery strains of wood fiber-plastic composites with different wood fiber contents（by mass） were measured. The effects of wood fiber contents on the creep behaviors of wood fi- ber-plastic composite were discussed. 24 h creep curves of wood fiber-plastic composite were fitted by ten element general Kelvin model and Findley＇s power law model. The effects of temperature on the creep be- haviors of wood fiber-plastic composite were tested. The results show that the resistances for creep strains of wood fiber-plastic composite are improved by increasing wood fiber contents at various testing condi- tions. When the wood fiber content increases from 50~ to 70%, the bending strength and elastic modulus of wood fiber-plastic composites are markedly elevated and creep strain in 24 h is reduced by about 58%, and the difference of recovery strain is not as obviously as the difference of creep strain. At 10% and 20% loading stress level, the 24 h creep recovery efficient of wood fiber-plastic composite with 50% wood fiber is similar to that with 60% wood fiber; while, at 30% loading stress level, the 24 h creep recovery effi- cient of wood fiber-plastic composite with 60% wood fiber is similar to that with 70% wood fiber. Both ten-element general Kelvin model and Findley＇s power law model fit 24 h creep curves of wood fiber-plastic composites well. The creep strain of wood fiber-plastic composite increases with increasing temperature; however, the creep stain of wood fiber-plastic composite could be restrained by increasing wood fiber con- tent in a certain temperature range.