Abstract: 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.

Key words: High-density polyethylene, Short carbon fiber, Piezoresistive behavior, Percolation network, Stability.