蠕变对发泡聚乙烯缓冲性能影响的研究

目的研究发泡聚乙烯(EPE)缓冲衬垫在受到内装产品长期静态压载后的缓冲特性变化规律。方法设定2个不同负载(15.3,22.2 kg)模拟某一类电子产品自重,并设置对照组,预载时间为72 h,进行静、动态缓冲特性实验,对比分析EPE产生不同程度的永久变形后,在不同预载量下的应力-应变曲线、最大加速度-静应力曲线及缓冲系数-最大应力曲线。结果预载使EPE静压的屈服阶段变短,吸能特性降低,最小加速度增大,最小缓冲系数增大。结论蠕变会显著降低EPE的缓冲性能,在对发泡材料进行缓冲特性研究时,应增加对材料初始形态的预处理,使其更加符合实际使用状况。

Effects of Cushion Property of Foamed Polyethylene EPE Cushioning Material Exerted by the Creep

Objective To analyze the changing characteristics of foamed polyethylene EPE cushion after a long time of product loading. Methods Two different load weights (-15. 3, 22. 2 kg) were set to simulate the weight of certain electronic product in this controlled study, with a preloading of 72 h, and the deformation of the internal buffer material after long time stacking compression was checked. Then the stress-strain curves, the maximum acceleration-static stress curves and cushion coefficient-maximum static stress curves under two different pre-loading weights were compared. Results Preloading could shorten the yield segments, decrease the property of energy-absorbing, and increase the minimal acceleration values and minimal cushion coefficient values. Conclusion Preloading could greatly weaken the cushioning performance of EPE buffer material. It is recommended that pre-conditioning should be done prior to the dynamic test for expanded materials, therefore it could better resemble the actual using condition.