Glass-Transition Temperatures of Polyamide Textile Fibers

Abstract

The glass-transition temperatures (T g ) of thirty-one polyamide homopolymers and copolymers of widely differing molecular structure have been determined by differential scanning calorimetry or, as fibers, by dynamic tensile property measurements, and the results have been related to molecular structure. The effect of water on T g has been determined, and it is shown that the extent to which saturation with water lowers T g of a dry polyamide fiber depends only on the average spacing of amide groups in the monomeric unit. From the value of T g for the water-saturated fiber, the dyebath temperature at which a sudden increase in color yield occurs can be predicted for one disperse-dye system. Finally a procedure is outlined that allows the calculation of each of the above quantities with a precision that averages about 7°C, from a knowledge of the structure of the polyamide monomeric unit.