Structure and Morphology Control in Polymer Forming Through the Thermal History

Abstract

Two examples of the application of the Continuous Cooling Transformation (CCT) method for investigating polymer solidification under processing conditions are illustrated. One example concerns the solidification behaviour of syndiotactic polystyrene (sPS) from the melt, showing an anomalous trend of density versus cooling rate, exhibiting a minimum around 1 °C/s. Once phase composition is obtained from WAXD deconvolution, density can be closely predicted, its minimum depending on the competition among crystalline phases upon increasing cooling rate. Another example regards the formation of Poly-Left Lactic Acid (PLLA) foams via Thermally Induced Phase Separation (TIPS) by starting from thermodynamically stable polymeric ternary solutions PLLA/Dioxane(solvent)/Water(non-solvent). The average pore size of the foams as-obtained depends on demixing time and temperature.