INFLUENCE OF MODIFIED NATURAL RUBBER ON PROPERTIES OF NATURAL RUBBER–CARBON NANOTUBE COMPOSITES

Abstract

ABSTRACT Carbon nanotube (CNT)–filled natural rubber (NR) composites were prepared by using an internal mixer and a two-roll mill. Various types of NR, including unmodified NR, epoxidized NR (ENR), and maleated NR (MNR), were used. The chemical reactions between rubber molecules and functional groups on the CNT surface were characterized by attenuated total reflection Fourier transform infrared spectroscopy. Cure characteristics, tensile properties, relaxation behavior, and electrical conductivity of the various gum rubbers and the CNT-filled rubber composites were investigated. It was found that the addition of CNTs significantly affected the composite properties. This is due not only to the excellent properties of the CNT itself but also to the physical and chemical interactions between modified rubber molecules and CNT surfaces. On comparison between the three types of NR, it was observed that the ENR-CNT composite showed the highest values of delta torque, tensile strength, and initial relaxation modulus. This confirms the homogeneous distribution of CNT particles in the ENR matrix, which in turn resulted from enhanced interactions of functional groups on CNT surfaces and epoxide groups in ENR molecules. Furthermore, electrical conductivity as a function of CNT content was examined to estimate the electrical percolation threshold value and to determine the state of dispersion of CNTs.