CHARACTERIZATION OF MOLECULAR-ORIENTATION IN HOT STRETCHED POLYSTYRENE

Differential scanning calorimetry (DSC) and birefringence was used to study molecular orientation of polystyrene. Models were developed relating the orientation and stress levels to the temperature, strain rate and amount of stretch. The number of relaxations observed on the DSC was influenced most by the temperature of stretch. At a temperature of 1.03 T(g) K, maximum relaxation peaks and maximum tensile properties were developed over a range of molecular weights and molecular weight distributions. At given process conditions, birefringence was found to be influenced by MBAR(w), while DSC enthalpy was influenced by MBAR(n).