短碳纤维填充HDPE复合体系的渗流网络与压阻行为

Percolation Network and Piezoresistive Behavior of HDPE Conducting Composites Filled With SCF

研究了短碳纤维 ( Short carbon fiber,SCF)填充高密度聚乙烯 ( HDPE)导电复合体系的渗流 ( Percola-tion)与压阻行为 ( Piezoresistive behavior,PRB) ,发现 SCF经物理接触而形成的导电网络是复合材料导电的根源 .体系的压阻行为呈现浓度依赖性 .受压时 SCF间隙的减小与渗流网络的局部破坏 -重建过程随填料浓度、载荷大小和力学循环次数的变化而变化 ,导致 PRB表现为电阻负压力系数 ( NPC)、电阻正压力系数( PPC)或两者兼有的现象 .讨论了体系 PRB的稳定性 ,发现由于 HDPE基体的塑性永久形变 ,电阻 -时间基线随着压缩循环的进行而发生漂移 。

Piezoresistive behavior(PRB) of high-density polyethylene(HDPE)-matrix conducting composite filled with short carbon fiber(SCF) was studied in relation to the structure alternation of the percolation network. Scan electron microscopy(SEM) micrographs revealed that the electrical conductivity of HDPE/SCF composites dominantly depended on the percolation network formed by the SCF physical contact. PRB was attributed to the changes of tunneling current and the destroying-rebuilding competition of the conducting long-carbon-chain as well as the percolation network. The resistance at zero stress after unloading decreased continuously with the increase of the number of compressive cyclic tests, which could be related to the residual compressive strain induced by the crystalline slippage and the intermolecular friction of the polymer matrix in the amorphous region. The stability of PRB could be improved significantly by a certain number of compressive cycles, and the improvement became more prominent as the volume fraction of SCF approached the percolation threshold.