Pressure Solidification of Amorphous Thermoplastics

It is assumed that solidification of a polymer melt is possible by applying pressure. Therefore, the influence of pressure on various properties of amorphous polymers was studied as reported in this article. Pressure-volume-temperature (pvT)-measurements were made on liquid and glassy polycarbonate as well as polymethylmethacrylate and cycloolefin-copolymer to calculate the thermal expansion coefficient and the shift of glass transition temperature with pressure. The existing pvT-apparatus was modified to measure the compression heating and the temperature of the polymer during the isothermal solidification process. All results are in good agreement with literature and show the feasibility of the process approach of pressure solidification for amorphous thermoplastics. In addition, the flow temperature of the materials was measured in a plate-plate-rheometer to identify the lowest process temperature possible. In addition, the results of the isothermal vitrification are discussed. It is shown that solidification occurs due to compression and that it can be proven by a change in compressibility and the volume course. POLYM. ENG. SCI., 49:154-161, 2009. (C) 2008 Society of Plastics Engineers