The use of a temperature programmable brabender mixing head for the evaluation of the processing characteristics of poly(vinyl chloride)

A technique is described for determining the temperature-torque profile of a PVC compound in a Brabender Plasticorder mixing chamber from room temperature to the temperature at which degradation occurs. Within this temperature range many PVC compounds show three characteristic peaks in the torque temperature trace. It is suggested that these three peaks are associated with the breakdown of the PVC powder particles (Stage III, 100 to 150 μm), micro-granules (Stage II, 0.5 to 2 μm), and primary particles (Stage I, 10 nm), respectively. The positions and shapes of these peaks are functions of the compound being investigated and as such can be used to characterize the processing behavior of the compound.

The greater part of the work has been carried out using suspension polymers but application of the technique to mass and emulsion polymers suggests that the conclusions are applicable to all polymers which possess a particulate substructure.