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The progress of cure reactions was observed for rubber sheets during the cooling period after their extraction from the mold. The study was performed by considering either motionless air at 125°C and water at 12°C for cooling the rubber previously cured in a mold kept at 160eC. A significant increase in the state of cure was calculated with the help of a numerical model for the vulcanizates, especially in the case of air at 125°C. An improvement in physical properties such as the swellling in toluene, and mechanical properties measured either under static or dynamic conditions, was determined. Some parameters were found of interest, especially the kind of cooling fluid and its temperature, and the state of cure of the vulcanizate at the time of extraction out of the midplane of rubber sheets where the state of cure was lower, cooling in air at 125°C was responsible for a development of the profiles of state of cure through the sample leading to a more homogeneous material.

SynopsisThis paper determines the increase in the state of cure through the rubber mass during the cooling period after the vulcanizate is removed from the mold. The problem is complicated because of the great number of parameters. Some of them, such as the dimension of sample, the state of cure through the rubber a t the time of its removal from the mold, the nature of the fluid, its agitation and temperature, are of interest. This work is concerned with the study of the effect of the temperature of motionless air in which the vulcanizate is cooled. This parameter is important in increasing the state of cure. Although the problem is complicated, it has been resolved by using a model based on a numerical method of calculation with finite differences. This model takes into account not only heat transfer by conduction through the rubber and by convection through rubber-air interface, but also the kinetics for heat evolved in the cure reaction.

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