Dynamic mechanical and physical properties of cyclized natural rubber blends

Natural rubber (NR) and cyclized NR (C-NR) containing 5,20, and 90% degree of cyclization were blended by dynamic vulcanization in a high shear environment using sulfur based curing systems at 160°C. In addition, the addition of sulfur compound in C-NR (90%) latex before vulcanization process was also studied. As expected, all blends with curing agents show an increase in hardness and modulus compared to the pure NR vulcanizates, except for rubber blend with C-NR (5%). Maximum hardness properties are obtained for NR/C- NR (90%) with the ratio 30/70. The vulcanization rate, observed by using oscillating disk rheometer, of rubber blends containing C-NR was slower than that of neat NR vulcanizate. All properties of the rubber blend containing cyclized NR, In which a sulfur compound was added to the cyclized NR latex before dynamic vulcanization, were better than those of samples after vulcanization process. According to the DMA results, the rubber blends containing C-NR (5 % or 20%) exhibited one peak, while the NR/C-NR (90%) represented two peaks.