Second‐order transitions in solutions of cellulose triacetate

Abstract

The system cellulose triacetate in chloroform has been studied using the technique of dilatometry, viscometry, and light‐scattering, and it has been observed that although under certain conditions the solutions can be induced to gel, gelation occurs without the change in volume to be expected for a first‐order transition. Two second‐order transitions have been observed however, which are still detectable while the system is in the liquid state. In addition, the transition temperatures have been found to be independent of concentration. An explanation for these unusual effects has been proposed, suggesting that the system contains submicroscopic, partly crystalline aggregates of polymer molecules, whole melting point lies above the temperature range studied. Gelation is considered to take place by a coalescence of these aggregates, and second‐order transitions to occur within the aggregates while the aggregates while the system is in an apparently liquid state.