Thermal diffusivity of polymers by the laser flash technique

Abstract

The nature of the molecular structure of plastics makes the properties of such materials markedly temperature dependent. Thermal conductivity, thermal diffusivity and specific heat, namely the thermal properties, are the three most important physical properties of a material that are needed for heat transfer calculations. Nowadays, several different techniques for the determination of the thermal diffusivity and thermal conductivity may be found in the literature. Recently, transient techniques have become the preferable way for measuring thermal properties of materials. In this work, the laser flash technique is employed in the experimental determination of the thermal diffusivity of some selected polymers. Measurements were carried out from room temperature up to 160 °C. Disc shaped samples 10 mm diameter and 0.3–1 mm thickness were prepared either by hot pressing the polymer powder, or by cutting the discs from long cylindrical commercial bars. The reproducibility is excellent, and the results obtained were checked against results obtained by the hot wire technique, and when possible, they were also compared with data found in the literature. The laser flash technique mostly employed in the determination of thermal properties of ceramics and metals may also be considered as a suitable method for measuring thermal properties of polymers.