Novel technique for following the rigidity changes accompanying the curing of polymers

Abstract
A method is described for measuring the rigidity of a curing polymer system throughout its complete course of reaction (liquid to solid). In this technique, a braided fiber (nylon), impregnated with the polymer system to be studied, is used as the supporting member for a free, torsionally vibrating mass. From the frequency of the vibration, the apparent rigidity modulus of the impregnated braid is calculated. The rigidity of the reacting polymer is thus followed nondestructively during the curing period. In a further development, the term relative rigidity /0 is introduced to normalize the rigidity parameter to a more experimentally adaptable quantity. The curing behavior of several types of polymer is presented to illustrate the general utility of the method.