Study On Anti-reversion Properties Of Naturalrubber Sulphur Vulcanization System

When the size of ZnO particle enters nano-meter magnitude, vulcanizedactivation is greatly raised because of nano-meter effect of ZnO, and studies showedthat nano-zinc oxide (NA) and in-situ surface modification nano-ZnO (YW) hadstronger activation than ordinary zinc oxide in different curing systems of NR.Firstly, the in-situ surface modified nano-ZnO were prepared using Si-69silanecoupling agent, and X-ray diffraction (XRD) demonstrated that average graindiameters of in-situ surface modified nano-ZnO was50nm, and X-Ray spectroscopy(SEM with EDS) showed that the dispersal of in-situ surface modified nano-ZnO inNR turned out to be no worse than that of ordinary ZnO.Secondly, the effects of different varieties of ZnO on anti-reversion properties andthe cure characteristics of NR vulcanizates cured with CV, SEV and EV cure systemsat143℃,153℃,158℃,163℃and168℃respectively, were studied. Nano-ZnO andin-situ surface modified nano-ZnO can greatly improve the crosslinking degree of NRvulcanizates cured with CV, SEV and EV cure systems, especially in EV cure system,as a result, nano-ZnO and in-situ surface modified nano-ZnO vulcanizates cured withEV cure systems increased by165.8%and155.3%respectively.Then, the effects of different varieties of ZnO on physical properties of NRvulcanizates cured with CV, SEV and EV cure systems at143℃,153℃,158℃,163℃,168℃respectively, were researched. Studies have shown that, in the NR a CV system,tensile strength and elongation at break of YW vulcanizate containing at158℃,respectively, was28.7MPa,440%.In addition, the crosslinking densities and different types of the crosslink bond of the vulcanizates were studied with the equilibrium swelling method and chemicalprobing method. Result showed that NR vulcanizates filled with in-situ surfacemodified nano-ZnO had the maximum total crosslinking density, monosulfidic anddisulfide crosslinking bond density, and improved24.46%,4.73%,25.76%and100%,respectively compared with the ordinary zinc.Finally, the high temperature vulcanization kinetics of CV, SEV and EV curesystems were studied. The kinetic parameters k and B of the vulcanization reactionwere obtained by linear fit, and the activation energy of NR compound addition ofdifferent varieties of zinc oxide in the heat curing stage were calculated by theArrhenius equation. Result showed that activation energy of CV cure system filledwith ordinary zinc oxide, nano-zinc and in-situ surface modification of nano-zincoxide were100.32KJ/mol,96.93KJ/mol and95.51KJ/mol, and SEV cure system filledwith ordinary zinc oxide, nano-zinc and in-situ surface modification of nano-zincoxide were84.75KJ/mol,106.68KJ/mol and73.74KJ/mol respectively.