Thermal Conductivity of Poly(lactic acid) in Solid and Molten States and Its Dependence on Temperature and Crystallinity

Thermal transport plays a critical role in both the processing and application of polymeric materials. The measurement of thermal conductivity in polymer melts and solids is challenging, and large variations in experimental results are common in the literature. The scarcity of reliable thermal transport property data severely inhibits efforts for polymer process design and optimization. Here, we use a robust optical technique to measure the thermal diffusivity of two grades of poly(lactic acid) polymers over a temperature range relevant to the processing of these materials. Combined with thermodynamic property measurements, we determine the thermal conductivity as a function of temperature and crystalline domain fraction.