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首页> 外文会议>International conference on woodfiber-plastic composites >Accelerated Weathering of Natural Fiber-Thermoplastic Composites: Effects of Ultraviolet Exposure on Bending Strength and Stiffness
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Accelerated Weathering of Natural Fiber-Thermoplastic Composites: Effects of Ultraviolet Exposure on Bending Strength and Stiffness

机译：加速天然纤维 - 热塑性复合材料的风化：紫外线暴露对弯曲强度和刚度的影响

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Mechanical properties of bending stiffness and yield stress were used to evaluate the effects of ultraviolet exposure on natural fiber-thermoplastic composites. Four different specimen formulations were evaluated. Injection molded high density polyethylene (HDPE) served as the polymer base for all formulations. Two lignocellulosic fillers, wood flour and kenaf fiber, were added at 50 percent by weight. Additives consisted of an anti-oxidant, coupling agent, and ultraviolet (UV) stabilizer. Specimens were exposed in a laboratory weatherometer to high levels of UV radiation and moisture cycling to simulate the effects of sunlight and rain for a 2000-h exposure period. Bending stiffness (modulus of elasticity) and bending yield stress (modulus of rupture) were measured prior to and after specific exposure periods. For the 100 percent HDPE formulation, stiffness increased and yield stress decreased after exposure. For HDPE with additives, no significant changes in mechanical properties occurred after 2,000 hours of exposure. Significant loss in mechanical properties was observed for both fiber-filled formulations. A 42 percent drop in measured stiffness and 24 percent drop in measured bending strength were recorded for the kenaf fiber formulation due to the 2,000-hr, exposure. A less dramatic drop in stiffness (33%) and strength (20%) was recorded for the wood flour formulation. For all formulations except HDPE with no additives exposed for 1,000 hours, the orientation of the degraded surface in bending, whether on the tension or compression side, had no significant effect on stiffness or strength.
机译：弯曲刚度和产量应力的力学性能评价紫外线暴露在天然纤维 - 热塑性复合材料上的作用。评估了四种不同的样品制剂。注塑成型的高密度聚乙烯（HDPE）用作所有制剂的聚合物基础。两种木质纤维素填料，木粉和keNaf纤维以50重量％加入。添加剂由抗氧化剂，偶联剂和紫外（UV）稳定剂组成。将标本暴露在实验室静止测量仪中，以高水平的紫外线辐射和水分循环，以模拟阳光和雨量的影响，为2000-H暴露时期。在特定暴露期之前和之后测量弯曲刚度（弹性模量）和弯曲屈服应力（破裂模量）。对于100％HDPE配方，暴露后，刚度增加，屈服应激降低。对于具有添加剂的HDPE，在2,000小时的曝光后没有发生重大变化。对于纤维填充的制剂，观察到机械性能显着损失。由于2,000小时，暴露，为keenaf纤维配制记录了测量刚度和24％的测量弯曲强度下降了42％。为木粉配方记录了刚度（33％）和强度（20％）的较小剧烈滴落。对于除HDPE除了未暴露1,000小时的HDPE外，弯曲的降解表面的取向对张力或压缩侧没有显着影响刚度或强度。

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