The effect of gypsum loadings on the curing characteristics and physicomechanical properties of natural rubber vulcanisates

Document Type : Research Paper


The effect of gypsum loading on curing characteristics and physico-mechanical properties of natural rubber vulcanisates were investigated over a range of filler loadings from 0 to 40 phr. Changes with minimum torque (ML), maximum torque (MH), scorch time (ts2), 90% cure time (tc90) and curing rate index (CRI), tensile strength, young modulus at 300% elongation (M300), elongation at break, hardness and rebound resilience with the filler loadings were investigated. The results revealed that the values of both the minimum torque and the maximum torque increased with the filler loadings. However, the scorch time was found to decrease and 90% cure time was almost unchanged with increasing filler loadings. The tensile moduli at 300% elongation and hardness increased, whereas, tensile strength, elongation at break and rebound resilience dropped with the addition of filler loadings.