The Glass Transition of Wool: An Improved Determination Using DSC

The glass transition temperature ( T _g ) of wool and its dependence on water content is reinvestigated using differential scanning calorimetry (dsc). Previous studies with dsc have not accounted for the influence of thermal history, which may introduce a large variability in T _g measurements. Because the T _g of wool is an important parameter affecting textile performance and properties, it needs to be clearly defined. When the finite volume of the water-impenetrable phase is taken into account, an important correction of the Fox equation is obtained, describing the dependence of T _g on water content. On melting of the water-impenetrable crystalline regions, a reduction in the temperature range of the glass transition region is apparent, suggesting that the crystalline regions behave in a manner analogous to filler particles in rubber. The ratio of the change in heat capacity at the glass transition, before and after melting, may provide a way to estimate the crystalline weight fraction in native wool.