ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
New Methodology and Apparatus for the Thermal Characterization of Semi-Crystalline Thermoplastics in Extreme Conditions
Sinopsis
During the forming of thermoplastic parts, the control and optimization of heat transfer are crucial because they impact on the quality of final part. The modeling of heat transfers requires a comprehensive and accurate knowledge of thermo-physical and crystallization properties of the polymer. However the experimental determination of these parameters is time consuming and requires several devices. In this work, we present a new apparatus associated to a methodology able to determine simultaneously the specific volume, the thermal conductivity and parameters of a crystallization kinetic model. This home-built PvT device is designed such as heat transfer is 1D through the radius of a sample with experimental conditions close to processing conditions: high temperature (up to 400°C), high cooling rate (up to 200K/min) and very high pressure (up to 200MPa). This apparatus controls the applied pressure on the sample while measuring its volume variation which corresponds to a direct measurement of the specific volume. Then the thermal conductivity and the crystallization kinetics are estimated without intrusivity by inverse methods based on a heat transfer model with moving boundaries, which takes temperature and crystallinity gradients into account. Our apparatus and methodology are tested on isotactic polypropylene, which is extensively studied in the literature. Measurements (specific volume) and estimated values (thermal conductivity and crystallization kinetics) are close to literature ones.