PE/CB复合材料的辐照效应

研究了两种炭黑(CB)对PE的影响及PTC功能材料挤出后的特性，发现挤出后粒子和聚合物取向对材料电性能都有较大影响。经γ射线辐照后HDPE／CB功能复合材料稳定性大为提高，初步探讨了辐射对PTC功能材料稳定性的影响。结合辐射交联等方法提高材料的稳定性。用扫描电镜(SEM)观测了一系列PE／CB的形态、CB的分布、链段的分子运动，并结合Fisher的toy model对PE／CB机制做了较系统的解释。

PE/CB Composites with PTC Properties were Made by γ-Rays Irradiation

High-density-polyethylene(HDPE) and low-density-polyethylene(LDPE) were used as the polymer matrices. Two kinds of carbon blacks ( CB) , high structure and low structure were used as the conductive filler. The positive temperature coefficient (PTC) intensity of the PE/CB composites was tested before and after irradiation. Compared to that of unirradiated HOPE/ CB composites, the positive temperature coefficient (PTC) intensity of the irradiated HDPE/CB composites is higher and the e-lectrical reproducibility of the irradiated HDPE/CB composites of is better. The effects of -y-rays irradiation were also estimated. The experimental results show that PTC effect and negative temperature coefficient ( NTC) effect of the composites were obviously influenced by the irradiation dose. The NTC effect was effectively eliminated when the radiation dose reached 400 kGy. The results show that the reproductive of the PTC effect is related to the adhesion between the interface of the polymer matrices and CB particles. These PTC phenomena and their distinctive aspects were described. Various micro strcture-esploring means were used to study conductive composites, such as scanning electron microscopy (SEM) ,wide angle X-rays diffraction (WAXD) and transmission electron microscopy(TEM). The explanations were given from the structural characteristics of the blends, CB particles distribution and the motion of polymer segments basesd on Fisher's toy model.