Rubber cooling stage

Cooling Stage of a Perfectly Cured Rubber Sheet in Motionless Fluid... 

The thermal properties of rubber are of very great importance, particularly in the processing stages, but there is a remarkable dearth of reliable data. Traditionally, the approach to heating and cooling problems was empirical rather than by careful analysis. The data needed for such analysis was not available, largely because of the undoubted experimental difficulties to be overcome but, even with data, somewhat complicated calculation is required. 

Place 2 litres (1760g, 36 mol) of concentrated ammonia solution (d 0.88, 35% w/w) (1) in a large (e.g. Winchester) bottle, cool thoroughly in an ice bath and pour in slowly 77 g (0.5 mol) of 2-bromopropanoic acid (Expt 5.164). Close the bottle with a rubber bung held in place with wire, and leave at room temperature for 4 days. Concentrate the solution to about 250 ml by distillation under reduced pressure using a rotary evaporator apply the vacuum with caution in the initial stages when most of the excess of ammonia is being removed. Filter, concentrate further to 150 ml, cool in ice and add 750 ml of... 

The neat epoxy resin was prepared by casting. The as-received B-stage material was subjected to degasification at 85 °C inside a vacuum oven. The softened resin was then transferred into a preheated silicon-rubber mold. The curing schedule was 121 °C for 2.0 hours, 177 °C for 2.5 hours, followed by a slow cooling at 0.5 °C per minute to room temperature (23.0 °C). 

As the evaporation is endothermic, the surface of the rubber is cooled differently during the stage of drying, depending on the rate of evaporation. 

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