Development of Crosslinked Flexible PVC Foam Formulations

Experiments were carried out to develop a peroxide based plasticised PVC formulation from which a crosslinked foam could be produced. Thermal analysis was used to investigate the reactions which occurred during crosslinking and blowing, and to select a suitable peroxide and crosslinking temperature. Solvent extraction was used to assess the amount of crosslinked material (gel content), and thermomechanical analysis was used to measure softening temperature of the foams produced. For selected samples, the reaction was scaled up so that tensile properties could be measured. Providing that a suitable peroxide was well dispersed in the plastisol, and in the presence of a crosslinking monomer, uniform crosslinked foams could be produced when a suitable spreading temperature was used. Gel content and softening temperature increased with peroxide and monomer concentration. The crosslinking reaction appeared to be similar to that occurring in the irradiation crosslinking of plasticised PVC studied previously.