Effect Of Cure Process On Microstructure And Properties Of Tire Compound

Tires are thick rubber products with poor thermal conductivity,resulting in different temperature fields and uneven cure degree in different parts of the cure process.Even if the cure degree is the same,if the cure process is different,it will lead to different microstructure,such as crosslinking density and filler dispersion,which will have a certain impact on the properties of rubber.It is of great significance to explore the changes of rubber structure and performance under different cure processes,so as to optimize the comprehensive performance of tires,and provide guidance for tire companies to establish grading standards for tire performance under different cure processes.In this paper,the tread,shoulder pad and cord compound in tire were vulcanized at 140℃,145℃,150℃,155℃and 160℃for 1.5 times and 2.0 times of process optimum cure time(t₉₀).The effects of different cure processes on the microstructure and properties of tread,shoulder pad and cord compound were studied.The results showed that:For tread compound,when the cure time was 1.5 times t₉₀,the tread rubber was in the optimum cure state,and when the cure time was 2.0 times t₉₀ and the cure temperature was lower than 150℃,the tread rubber was too,but when the cure temperature reached 150℃,the tread rubber vulcanized for a long time was in the state of reversion;when the cure temperature was≤150℃,the crosslinking network of vulcanizate with long cure time was more perfect,and when the curing temperature was>150℃,the crosslinking network with short curing time was more perfect;With the increase of cure temperature,the scorch time of tread rubber was shortened,and the dispersion of filler was relatively good;The tear strength of tread rubber decreased significantly with the increase of cure temperature and cure time,and other physical and mechanical properties did not change significantly;With the increase of cure temperature,the wear resistance decreased,and the samples vulcanized for a short time had better wear resistance;The effect of cure process on wet sliding and rolling resistance was not obvious.For shoulder pad rubber,when the cure time was 1.5 times t₉₀,the shoulder pad rubber was in the optimum cure state;When the curing time was 2.0 times t₉₀,the shoulder pad rubber was in the state of reversion;When the cure time was 1.5 times t₉₀,the crosslinking density of the vulcanizate reached the highest when vulcanized at145℃,and the crosslinking network was more perfect;With the increase of cure temperature,the dispersion of filler was relatively good;Under the influence of crosslinking density and filler dispersion,the tear strength and constant elongation stress of shoulder pad rubber were higher when vulcanized at 145℃,while the tensile strength and elongation were higher when vulcanized at high temperature;The shoulder pad Rubber vulcanized at low temperature for a long time had less heat production due to compression.For cord rubber,when the cure time was 1.5 times t₉₀,the cord rubber was in the optimum cure state and was not in the state of reversion.However,when the cure time was 2.0 times t₉₀,the cord rubber began to be over sulfurized.The higher the cure temperature,the greater the degree of over sulfurization;The crosslinking density of the samples vulcanized at 1.5 times t₉₀ cure time was greater than that of the samples vulcanized at 2.0 times t₉₀.With the increase of cure temperature,the crosslinking density decreased and the crosslinking network of the vulcanizate deteriorated;With the increase of cure temperature,the dispersion of filler was relatively good;The tensile properties and tear strength of cord compound decreased significantly with the increase of cure temperature and cure time.The constant tensile stress of long-time vulcanized compound was slightly higher than that of short-time vulcanized sample;affected by various network structures,different cure processes had no obvious effect on the compression heat generation performance of cord rubber.