Abstract
Graft copolymers of NR and PMMA (i.e., NRโgโPMMA) were prepared with the bipolar redox initiation system, using various percentages of molar ratios of NR/MMA at 95/5, 90/10, 80/20, 70/30, and 60/40. It was found that the Mooney viscosity, shear stress, and shear viscosity of the NRโgโPMMA increased with an increase in the molar ratio of MMA used in the graft copolymerization. This may be attributed to an increasing trend of the chemical interaction between polar functional groups within the grafted PMMA molecules. Furthermore, a decreasing trend of storage moduli was observed with increasing molar ratios of MMA. The glass transition temperature was obtained from the tan ฮด curves. We found a slightly increasing trend of the T~g~'s with an increase in molar ratios of MMA used in the grafting reaction. The NRโgโPMMA was later compounded using TBBS as an accelerator. With an increase in molar ratios of MMA in the grafting reaction, we observed an increasing trend of minimum torque, maximum torque, cure time, and scorch time, but quite similar levels of torque difference and crosslink density. Furthermore, the tensile strength of the NRโgโPMMA gum vulcanizate increased with an increase in molar ratios of MMA, whereas the elongation at break decreased. ยฉ 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1600โ1614, 2006