HDPE/纳米SiO_2杂化材料的动态流变行为研究

The Study of the Dynamic Rheological Behavior of the HDPE/Nano-SiO_2 Hybrid Materials

通过熔融接枝反应将乙烯基三甲氧基硅烷(VTMS)接枝到高密度聚乙烯(HDPE)分子链上,以四乙氧基硅烷(TEOS)为前驱体,加入接枝的HDPE中,通过溶胶-凝胶法(Sol-Gel)制备了HDPE/SiO2杂化材料,使用平板流变仪研究了纳米SiO2对HDPE/纳米SiO2杂化材料的动态流变行为的影响。结果表明,当SiO2含量达到1.2%时,复数黏度η*发生突变,并出现强烈的剪切变稀;低频区,储能模量G′、损耗模量G''出现第二平台;对应的应变γ-G′曲线上,体系出现两段线性粘弹区域。这些现象表明由于杂化体系中纳米SiO2粒子与基体聚合物间通过化学键链接,并且均匀分布,在纳米粒子的含量达到1.2%时,粒子间就会发生似固体的关联行为。

Vinyl trimethoxysilane（VTMS） was grafted to the chain of the high density-polyethylene（HDPE） via melt grafting reaction.The tetraethoxysilane（TEOS） which acts as precursor was mixed with grafted HDPE,and then the HDPE/SiO2 hybrid materials were prepared by sol-gel process.The dynamic rheological behavior of the prepared high density-polyethylene/nano-silica hybrid composites was investigated by plate rheometer.Experimental results show that the complex viscosity（η＊） of the composites increases with increasing the content of SiO2.When the SiO2 content of the hybrid composite reaches 1.2%,its complex viscosity η＊ increases suddenly and the shear thinning behavior appears.In the low frequency region,both the curves of the storage module G′ vs.frequency and loss module G″ vs.of the HDPE/SiO2 appear a second flat;and on the curve of the strain γ vs.storage module G′,there appears two linear viscoelastic sections.These phenomena can be attributed to the links between the nano-SiO2 particles and polymer matrix in the hybrid system by chemical bonds and the uniform distribution of the nano-SiO2 particles;while when the nano-SiO2 content reaches 1.2%,the ＂solid-like＂ behavior may occur between the particles.