Development of a method for pressure-free volumetric dilatometry of polymer melts and solids

The tendency of polymers to shrink upon cooling and to expand upon heating strongly affects polymer processing operations. Therefore, quantifying these properties through dilatometry is crucial. Existing setups to measure dilatometry are, however, mostly limited to solid samples, or are expensive and impractical to use. Moreover, upcoming forms of polymer processing such as additive manufacturing techniques or more commonly named 3D-printing techniques require these properties to be measured under atmospheric pressure, which is not possible with most of the existing setups. Therefore, this paper describes a novel method for pressure-free volumetric dilatometry that is able to characterize samples in both liquid and solid phase, and during liquid-solid transitions. The principle of the method is based on the use of a highly viscous confining fluid that, in combination with a simple piston-die sample container, offers a cheap, easy-to-use and safe method to measure volumetric dilatometry on a variety of samples. The method is verified by comparison with standards and data from literature.