Single-wall Carbon Nanotubes in Vulcanisates Based on Different Rubbers: Investigation of the Dynamic Mechanical Characteristics

Abstract

The dynamic mechanical properties of sulphur vulcanisates based on different rubbers containing single-wall carbon nanotubes (SCNTs) were studied. Components of the dynamic modulus (G′ and G″) and the temperature dependence of the mechanical loss tangent tg δ were obtained on a DMS Ares instrument (Reometrics) at an amplitude of 0.5%, a frequency of 1 Hz, and a heating rate of 1°C/min at temperatures ranging from −80 to +80°C. The glass transition temperature T_g was determined as the temperature of the maximum on the temperature dependence of tg δ. The morphology was studied on transmission and scanning electron microscopes. Rubber compounds based on hydrogenated nitrile butadiene rubber (HNBR Therban 3496), styrene butadiene rubber (Sprintan SLR 4502), and natural rubber (NR of grade SMR CV60) were chosen. SCNTs (1%) were introduced into composite YU-58 containing NR latex (98%) and polyvinylpyrrolidone (1%). This composite was regarded as the filler. The properties of composites containing SCNTs with a carboxylated surface (SCNT-COOH) were also studied. To calculate the parameters of the two-phase ‘rubber (matrix)–filler’ system at temperatures of −70, −30, and +23°C, we used the Kerner equation. There is a notable trend towards an increase in the flexibility of the macromolecules. For NR-based composites containing 0.3% SCNTs, the calculated value of G′ of the boundary layer at −30°C is 10 times higher than the G′ value of the matrix, and 15 times higher at +23°C. Deliberations concerning the nature and properties of the boundary layer are laid out.