Viscoelastic damping properties of natural rubber-epoxidized natural rubber composites

In order to improve the damping performance of natural rubber (NR), it was blended in mass ratio of 20:80 with epoxidized natural rubber (ENR) of different epoxidation degrees in a mixer to obtain blend rubber matrix of ENR-NR. The ENR-NR matrix was further filled in mixing and smelting process with other components (sulfur, accelerator 2,2'-dibenzothiazole disulfde(DM), promoter N-cyclohexylbenzothiazde-2-sulphenamide(CZ), ZnO, stearic acid, carbon black) to prepare a wide temperature-range damping ENR-NR matrix composites. The dynamic mechanical properties and the damping characteristics of the plasticized ENR-NR mixtures and their vulcanized rubbers were tested by rubber processing analyzer (RPA) and DMA. The results show that epoxidation of NR enhances the rigidity local molecular chain and improves the adhesion between the matrix and the fillers while ENR adsorbing more carbon black is inhomogeneously dispersed in the continuous phase NR. ENR and its blend rubber with NR exhibit higher viscosity and storage modulus for ENR with higher epoxied degree. The combination of ENR into NR can obtain materials with better elastic and damping performances for vulcanizates when damping range is widened to higher temperature for ENR-NR compound rubber. The effective range is -57-1℃ for ENR-NR with epoxidation degree 25 in comparison with -57——20℃ for NR although there is ineffective damping zone for composite rubber when natural rubber being epoxidized to higher degree. However, the addition of a small amount of ENR has little effect on the hardness, modulus and elongation at break of NR matrix composite.