超细颗粒填充高密度聚乙烯复合体的导电和流变学性质(英文)

制备了多壁碳纳米管、石墨和碳黑填充高密度聚乙烯(HDPE)复合体,研究了复合体的导电和流变学性质.利用隧道逾渗模型对关键指数分别为4.4、6.4和2.9的三种复合体的"非普适性"导电行为进行了解释.与此同时,考察了颗粒类型和含量,以及剪切速率对复合体流变学性质的影响.结果表明,复合体系的储能模量在低频区出现"第二平台",而复合黏度则表现出强烈的剪切变稀行为,标志着颗粒在聚合物内部发生聚集形成了网络结构.与石墨和碳黑填充复合体相比,具有更高纵横比的多壁碳纳米管填充复合体具有更高的储能模量和复合黏度.基于Guth-Smallwood理论结合有效介近似的G′r分析结果表明,填充HDPE复合体系的流变学逾渗阈值和导电逾渗阈值吻合良好.

Electrical and Rheological Properties of High Density Polyethylene Composites Filled with Ultrafine Particles

The electrical and rheological properties of high density polyethylene (HDPE) composites filled with multi-walled carbon nanotubes (MWCNTs), graphite (G) and carbon black (CB) were evaluated. And in particular, the non-universal electrical behavior of the composites was observed with a critical exponent t of 4.4, 6.4, and 2.9, respectively. The effects of filler type, shearing frequency and filler content on the rheological behavior of the composites were investigated, and the relationship between the rheological and electrical percolation threshold of the filled HDPE composites was interpreted in relation to tunneling-percolation model. Results show that a "second plateau" of storage modulus and strong shear thinning behavior are induced at low frequencies by aggregation of fillers. The HDPE composite filled with MWCNTs possesses larger complex viscosity and storage modulus than those filled with CB and G, which is closely related to the higher aspect ratio of MWCNTs. Moreover, the analysis by modified Guth-Smallwood theory combined with effective medium approximation indicates that the relative modulus (G'r) of the filled composites shows a percolating transition at an increased filler content. And the rheological percolation threshold conforms well to the electrical percolation threshold.