Characterization of irradiated epoxidized natural rubber/polyvinyl chloride/carbon nanotubes nanocomposites

Abstract

The effects of carbon nanotubes addition and irradiation modification on the characterization and properties of epoxidized natural rubber (ENR-50)/poly(vinyl chloride) (PVC)/multi-walled carbon nanotubes (MWNTs) nanocomposites were investigated. ENR-50/PVC/MWNTs nanocomposites were prepared by melt mixing in a Brabender Plastigraph at 150 °C with a rotor speed of 50 rpm followed by compression molding at 160 °C. The samples were irradiated in a 2 MeV electron beam machine in a dose range from 50 to 200 kGy. The functional groups, gel content, morphology, dynamic mechanical properties, volume resistivity and tensile properties of the resulting composites were investigated as a function of MWNTs contents, functionalized MWNTs and irradiation dose. Gel content confirmed the existence of irradiation-induced crosslinking. The highest gel content value was recorded at 8 phr of MWNTs content in nanocomposites. At 0 kGy (up to 6 phr), the MWNTs-COOH had higher gel content value. However, after irradiation (150 kGy), MWNTs nanocomposites recorded the highest gel content value. The x-ray diffraction pattern showed that 2 phr MWNTs content nanocomposites had a better degree of crystallinity than 8 phr MWNTs content and the degree of crystallinity was enhanced after irradiation. The addition of 8 phr of all MWNTs led to the increase of storage modulus and glass transition temperature, and was further enhanced after irradiation (200 kGy). Based on dynamic mechanical analysis results, 8 phr of functionalized MWNTs had better crosslinking as compared with unfunctionalized MWNTs. Volume resistivity increased with increasing MWNTs contents and irradiation dosage. The functionalized MWNTs showed higher resistivity at 0 and 150 kGy of irradiation doses. The tensile strengths of the irradiated nanocomposites increased up to 8 phr of unfunctionalized MWNTs, 6 phr of MWNTs-COOH and 10 phr of MWNTs-OH above 50 kGy. The modulus 100 (M100) increased and elongation at break (Eb) decreased with increasing of MWNTs content and irradiation doses. Functionalized MWNTs showed higher M100 and lower Eb at 0 kGy. However at 200 kGy of irradiation dose, the M100 was lowered and Eb was higher for functionalized MWNTs nanocomposites.