Characteristics of ethylene - Methyl methacrylate copolymer and ultrahigh molecular weight polyethylene composite filled with multiwall carbon nanotubes prepared by gelation/crystallization from solutions

Ultrahigh molecular weight polyethylene (UHMWPE) and ethylene-methyl methacrylate copolymer (EMMA) composites containing multiwall carbon nanotubes (MWNTs) were prepared by the gelation/crystallization method. The conductivity and Young's modulus were obtained as a function of EMMA content. When 5 wt% MWNT was admixed into neat EMMA known as an insulator, conductivity of the composite reached ca. 0.05 S/cm, which was much higher than the conductivity of UHMWPE with 5 wt % MWNT. The UHMWPE/EMMAMWNT composite containing 14 wt % EMMA and 5 wt % MWNT could be stretched up to 50 times. The conductivity and Young's modulus reached 3.84 × 10^-3 S/cm and 37 GPa, respectively, which denoted a successful result for preparing a conductive material with high modulus. The electrical conductivity of the composite increased with increasing draw ratio, indicating that the band gap became narrower by elongation. Furthermore, the conductivity increased with elevating temperature, but it tended to decrease beyond the melting point of the composites. Such a temperature dependence of the conductivity is perfectly different from the characteristics of polymer-carbon fiber and polymer-carbon black particles reported already. Such interesting phenomena were mainly analyzed by using X-ray and scanning electron microscopy in terms of morphological aspects.