Radiation-induced polymerization of glass-forming systems. III. Effect of melting point and glass transition temperature on the formation of the glassy phase

The general empirical rules about glass formation of organic compounds including monomers were studied. It was found that the difference of T_m (melting point) and T_g (glass transition temperature) was the most important factor in glass formation, that is, the glass-forming property of organic systems, mono- or multicomponent, could be expressed as a function of T_m and T_m – T_g at the cooling temperature ?196°C. The glassforming property was further divided into four classes according to the relation between T_m and T_m – T_g, and each class was related to several patterns in DTA curves. From these results it was clarified that the phases are completely or partially glassified depending on the different values of T_m – T_g in eutectic and noneutectic compositions. The overall phase diagrams covering the whole composition with the variation of T_m and T_g were determined, and they also supported the relationship between T_m – T_g and the glass-forming property. The distinct glass-forming property of binary systems with large molecular interaction was attributed to the great lowering of T_m and elevation of T_g in those systems. The effect of the number of components on glass formation was also studied; it was shown that if T_m, T_g, and ΔH (sum of heat of melting and of mixing) are given, the number of components necessary to glassification can be estimated.