Thermal properties of samples prepared from polylactic acid by 3D printing

In this contribution are described thermal properties (thermal conductivity, specific heat capacity and thermal diffusivity) of objects prepared from PLA (polylactic acid) filaments by 30 printing. The step wise transient method was used, which allows the determination of all parameters using a differential fractal heat transfer model. It was found that the determined thermal parameters depend on the thickness of the measured samples. This is due to the uneven heat transport through the sample. For the measurement of the thermal conductivity it is suitable to use thin samples, where the heat passes to the thermocouple evenly over the entire surface, unlike the measurement of the specific heat capacity where thick samples are used because heat is accumulated mostly in the sample volume. From the extrapolation/interpolation of the values of the determined thermal parameters, the correlation between the sample thickness and the thermal parameters can be found. Then real thermal parameters of the material can be determined. In our case for the transparent PLA, the value of the thermal conductivity and the specific heat capacity was determined as 0.12 W/m/K and 1200 J/kg/K, respectively, that agree with the tabulated values of the material.