EFFECT OF FILLER TYPE AND CONTENT ON PHYSICAL AND MECHANICAL PROPERTIES OF NR/SBR NANOCOMPOSITE BLEND

The effect of type and content of nanofiller on the cure behavior, cure characteristics, and mechanical and dynamic mechanical thermal properties of the vulcanized SBR/NR (30/70) blend nanocomposites containing carbon black were investigated. Halloysite nanotube (HNT) and calcium carbonate (CaCO3) nanoparticles were used as reinforcing agents at different levels ranging from0 to 5 phr. Two nanofillers affected the cure characteristics of the blended vulcanizates in opposite ways. While the gradual incorporation of HNT into the elastomer blend shortened the scorch time along with an increase in the effective torque of resulting nanocomposite compared to the unfilled blend, the progressive addition of CaCO3 into the blend monotonically prolonged the scorch time in conjunction with a decrease in the effective torque of vulcanizate sample. Mechanical tests showed enhanced elastic modulus and tensile strength of HNT-filled nanocomposites as the HNT content was increased. Nanocomposites reinforced with HNT exhibited significantly higher extensibility than the unfilled blend. In the case of CaCO3-filled nanocomposites, the elasticmodulus and ultimate strength decreased upon the addition of CaCO3 nanoparticles, whereas the strain at break showed a substantial increase compared to unfilled compound. Dynamic mechanical thermal analysis results revealed a monotonic shift of damping peak's temperature toward higher temperatures with HNT loading in HNT-filled vulcanizate nanocomposites. For CaCO3-filled nanocomposites, the damping peak's temperature shifted to higher temperatures at first and then shifted back to lower temperatures at higher loadings of CaCO3. The damping peak's intensity of the CaCO3-filled nanocomposites was considerably higher than the unfilled blend, indicating higher damping capability in these systems.