CHARACTERIZATION OF MOLECULAR-ORIENTATION BY DIFFERENTIAL SCANNING CALORIMETRY .3. INJECTION BLOW MOLDING OF POLYSTYRENE

Differential scanning calorimetry was used to study part quality from an injection blow moulding machine producing polystyrene thin-walled containers. Cavity-to-cavity, within cavity and shot-to-shot problems were detected. Multiple relaxation peaks observed in the temperature range T(g)-T(LL) had the relationship T(j) = 1.02 T(i) K, for T(LL) greater-than-or-equal-to T(j) > T(i) greater-than-or-equal-to T(g) and (j - i) = 1. Based on some simple assumptions, a model was developed that allowed the multiple peaks be resolved between the injection moulding and blowing steps of the process and into a three-dimensional array.