The electrically conductive CB/HDPE composites were prepared by melt compounding method. These CB/HDPE composites present positive temperature coefficient (PTC) phenomenon in which the resistivity was sharply increased near the crystalline melting temperature and negative temperature coefficient(NTC) phenomenon in which the resistivity was sharply decreased above the crystalline melting temperature. The electrical conductivity and PTC intensity of composites were affected by preparation conditions such as heat treatments, stretchings, and thermal shrinkage etc., resulting from the changes of the degree of crystallinity and crystal orientation of composite films. It was also found that the crosslinking reaction of silane treated composite induced the disappearance of the NTC phenomenon and the improved reproducibility of PTC phenomenon.

전기 전도성이 우수한 카본블랙(CB)과 고밀도 폴리에틸렌(HDPE)을 용융 가공법으로 혼합하여 전기 전도성 CB/HDPE 복합재료를 제조하였다. 제조된 CB/HDPE 복합재료는 승온시 모체인 HDPE의 결정용융온도 근처에서 전기 저항이 급격히 증가하는 PTC(positive temperature coefficient) 현상과 이후 저항이 다시 감소하는 NTC(negative temperature coefficient) 현상을 나타내었다. 복합재료의 전기 전도도와 PTC 강도는 열처리, 연신, 열수축 등과 같은 제조조건의 변화에 따른 결정화도, 결정배향도 등의 변화에 따라 크게 영향을 받는 것으로 나타났다. 또한 switching 성질에 심각한 장애가 되는 NTC 현상을 제거하기 위해 복합재료를 실란 가교처리 하였으며, PTC 현상의 재현성도 향상시켰다.

Keywords: Carbon black; Composite; Positive temperature coefficient; Negative temperature coefficient