Influence of Crystallization on the Sorption of Hydrocarbons by Natural Rubber and Gutta-Percha

Abstract

It has been known that the mechanical properties and structure of amorphous and of crystalline polymers differ from one another sharply. However, the influence of the phase state of polymers on their thermodynamic properties has not been made clear. Hence it has been of interest to evaluate the effect of polymer crystallization on the polymer's sorption properties. For this purpose it was essential to compare the sorption properties of a polymer which can exist in either the amorphous or the crystalline state at the very same temperature. The most suitable material is natural rubber, which is capable of crystallizing either during prolonged aging or under stress and, therefore, may be obtained at the same temperature in both the amorphous and the crystalline states. With the aid of a McBain balance in a high vacuum and under isothermal conditions, curves for the sorption of n-hexane by amorphous and crystalline samples of natural rubber at 0° and 25° C were obtained. In the experiment at 0°, the sorbent consisted of strips of natural rubber, some of which had been aged 8 months at 0° (the crystallized sample), and others aged for the same period at room temperature (the amorphous sample).

Structural, Adsorption, and Mass-Transfer Properties of Polycaproamide

“…The different desorption and adsorption isotherms were explained earlier by glassification of the polymer outer layers [10]. The PCA differential structural curve (2) that was calculated from the desorption isotherm ( Fig.…”