The “Freezing” of Raw Rubber

Abstract

Abstract The experiments lead to certain general conclusions. 1. Measurements of the changes in density, hardness, and light absorption show that all three properties suddenly decrease at the same temperature, doubtless as a result of the fusion of a crystalline component. 2. Measurements by means of a Bunsen ice calorimeter show that hard frozen samples of rubber have a definite heat of fusion. 3. The “melting point” of frozen rubber changes as time goes on, a phenomenon which may be explained by the growth of crystals. 4. A study of the freezing of raw rubber at ™10° C. and at 4° C. shows that freezing occurs in a few days, and that such rubber melts at a lower temperature than rubber which has been kept frozen for several years, phenomena which are explainable by the ordinary known laws of crystallization.