叠加振动剪切对PE–LLD的结晶性能与力学性能影响

Effect of Superimposed Oscillatory Shear on Crystalline Behavior and Mechanical Properties of PE–LLD

提出了一种新的振动剪切形式——叠加振动剪切,并从聚合物流动性角度分析了叠加振动剪切与普通振动剪切的区别。通过对比实验发现:相比普通振动剪切加工试样,叠加振动剪切加工的线性低密度聚乙烯(PE–LLD)具有更加完善的结晶过程,结晶度提高至43.5%,同时,拉伸强度和拉伸弹性模量分别提高了11%和12.6%,这主要是因为叠加振动剪切加工中存在变化的剪切速率迫使PE–LLD分子链不断受到小幅度的挤压–拉伸作用,形成更加完善的晶体结构,从而提高了PE–LLD的结晶度和力学性能。同时也表明叠加振动剪切比普通振动剪切具有更复杂变化的剪切速率,从而PE–LLD表现出更佳的自增强效果。

A new kind oscillation shear form named superimposed oscillatory shear （SOS） was proposed and the difference between oscillatory shear（OS） and SOS was analyzed. The comparison experiment indicate that compared with the samples under OS, liner low destiny polyethylene （PE-LLD） prepared under SOS exhibits an enhanced crystallization process, the degree of crystallinity is raised to 43.5%, and the tensile strength and Young＇ s modulus are improved by 11% and 12.6%, respectively.This is attributed to the continuous changed shear rate in SOS, which coiled and stretched the PE-LLD molecule chain and formed a more perfect crystal, therefore, the degree of crystallinity and the mechanical properties are improved. Meanwhile, these results suggest that SOS has a more complicate changes in shear rate than normal OS and PE-LLD prepared under SOS shows a better self- enhancement.