四川大学傅强团队报道了通过热处理和电处理制备具有优异加工性、机械性能和PTC效应的自限位加热电缆。相关研究成果发表在2024年1月11日出版的国际学术期刊《中国高分子科学杂志》。

聚合物/导电填料复合材料已广泛用于制备具有正温度系数（PTC）效应的自限热电缆。聚合物基体中导电填料分布和网络的控制是PTC材料性能的关键。为了补偿加工过程中强剪切对填料网络结构的破坏，通常在聚合物基体中添加过量的导电填料，这反过来又牺牲了其加工性和机械性能。

该文中，研究人员开发了一种简单的挤压电缆后处理方法，包括热处理和电处理，以生产具有优异PTC效应的高密度聚乙烯（HDPE）/炭黑（CB）电缆。研究发现，对于挤压态样品，强剪切使CB颗粒均匀分散在HDPE基体中，形成导电路径需要25wt%的CB。对于热处理的样品，观察到CB填料结构逐渐聚集，这导致PTC效应的改善和CB含量显著降低到20wt%。

非常有趣的是，对于综合热处理和电处理的样品，CB颗粒聚集并沿着电场方向定向，以产生实质性的导电路径，这导致CB含量进一步降低至15wt%。通过这种方式，同时实现了具有优异加工性、机械性能和PTC效应的自限位加热电缆。

附：英文原文

Title: Preparation of Self-limiting Heating Cables with Excellent Processability, Mechanical Properties and PTC Effect via Thermal and Electrical Treatments

Author: Tian-Hao Yang, Tong Wu, Qiang Fu

Issue&Volume: 2024-01-11

Abstract: Polymer/conductive filler composites have been widely used for the preparation of self-limiting heating cables with the positive temperature coefficient (PTC) effect. The control of conductive filler distribution and network in polymer matrix is the most critical for performance of PTC materials. In order to compensate for the destruction of the filler network structure caused by strong shearing during processing, an excessive conductive filler content is usually added into the polymer matrix, which in turn sacrifices its processability and mechanical properties. In this work, a facile post-treatment of the as-extruded cable, including thermal and electrical treatment to produce high-density polyethylene (HDPE)/carbon black (CB) cable with excellent PTC effect, is developed. It is found for the as-extruded sample, the strong shearing makes the CB particles disperse uniformly in HDPE matrix, and 25 wt% CB is needed for the formation of conductive paths. For the thermal-treated sample, a gradually aggregated CB filler structure is observed, which leads to the improvement of PTC effect and the notable reduction of CB content to 20 wt%. It is very interesting to see that for the sample with combined thermal and electrical treatment, CB particles are agglomerated and oriented along the electric field direction to create substantial conductive paths, which leads to a further decrease of CB content down to 15 wt%. In this way, self-limiting heating cables with excellent processability, mechanical properties and PTC effect have simultaneously been achieved.

DOI: 10.1007/s10118-024-3074-z

Source: https://www.cjps.org/en/article/doi/10.1007/s10118-024-3074-z/