A novel method for characterizing temperature-dependent elastic modulus and glass transition temperature by processing the images of bending cantilever slender beams at different temperatures

Abstract

We propose a novel method for estimating the elastic modulus of several materials by processing the bending image of cantilever material sheets. The calculated results (tested for five samples) were consistent with data obtained by direct measurement using a tensile strength device. By placing the cantilever sheets in an environment inside of which the temperature could be controlled, we were able to obtain the temperature dependence of elastic modulus. We identified a drastic drop of elastic modulus at a certain temperature and assumed this temperature corresponds to glass transition temperature. We also introduced an equation for describing the elastic modulus around that critical temperature and were able to estimate the glass transition temperature for all tested polymer materials. Surprisingly, the estimated glass transition temperatures conform to data obtained by direct measurement using a DTA device. Since the elastic modulus changes suddenly around the glass transition temperature, the proposed method might be more accurate than measurement using a DTA device where the glass transition temperature corresponds to the location of a weak peak at the DTA curve. This is the first attempt for estimating the glass transition temperature of polymer based on bending of cantilever slender beam, and seems to be the simplest method. The method is very potential for developing new equipment for determining the glass transition temperature of polymeric materials.