The Effect Of Vulcanization Process On The Microstructure And Properties Of NR Vulcanizates

In this paper, the effects of curing temperature，curing time and curing pressureon chemical crosslink network, filler network, dynamic mechanical properties andphysical mechanical properties of NR vulcanizates, which filled with carbon blackand sillca respectively, were investigated by means of Magnetic Resonance Cross-linkDensity Spectrometer(MR-CDS3500),Rubber Process Analyzer(RPA2000), ScanningElectron Microscope(SEM),Dynamic Mechanical Spectroscopy(DMTS) and theiranalysis methods, the effect of scorch time on microstructure and properties of NRvulcanizates was also investigated by changing the dosage of anti-scorchingagent,with the aim to define the key parameters that affect microstructure andpeoperties of vulcanizates, and their control methods.The results showed that: in comparision, the effects of curing temperature andcuring time on network and properties were larger than the effects of curing pressureand scorch time.With the increasing of curing temperature, two kinds of compound were moreeasier tend to reversion, crosslinking density decreased; filler dispersion became bad,and the degree of filler network increased; dynamic mechanical properties have a littlechange, physical mechanical properties generally decreased.With the prolonging of curing time, crosslinking density of both two kinds ofvulcanizates increased first and then decreased; the degree of filler network increased;tanδ and dynamic mechanical properties had a slight change; physical mechanicalproperties generally decreased， but compression heat decreased;compared withvulcanizates filled with carbon black, silica filled vulcanizates had better dynamic mechanical properties.With the improving of curing pressure, the crosslinking density of two kinds ofcompound had a slight change; filler network was easier to be broken, and the degreeof filler network decreased;the change of dynamic mechanical properties ofvulcanizates filled with carbon black was not obvious,the dynamic mechanicalproperties of vulcanizates filled with silica was the worst at8Mpa,and the othervulcanizates cured at different curing pressure were almost the same, physical andmechanical properties had little change.With the increasing of CTP dosage, the scorching time of both two kinds ofcompounds were prolonged obviously; crosslinking density tend to decrease; filler’sdispersion became bad; dynamic mechanical properties had little change; physical andmechanical properties tend to decrease generally，especially for compression heat andcompression，therefore, there is no need for us to add a lot of anti-scorching agent, ifscorching time can satisfy our need.