Effect of Time and Temperature on Plasticizer Absorption of Suspension Poly (vinyl chloride) Resin

Plasticizer absorption of suspended poly(vinyl chloride) (S-PVC) were determined under various time and temperature. The morphology of S-PVC grains under different plasticizer absorption conditions was characterized by scanning electron microscopy (SEM). The results showed that S-PVC grains were composed of multilevel particles, and there were grooves and pore channels among these particles. The S-PVC grains were spread and swelled by plasticizers entering through those grooves. The plasticizer adsorption of S-PVC which depended on temperature and time was a four-step unsteady process, named "first induction period", "first swelling period", "second induction period", and "second swelling period". At the "first induction period", the grooves of S-PVC grains were slowly wetted and spread by plasticizers; the pores among the agglomerates were swelled with an accelerated absorption at the "first swelling period"; while at the "second induction period", the intervals among the primary particles were slowly swelled after a swelling equilibrium; and at the "second swelling period", the space between molecular chains were rapidly occupied and swelled by plasticizers. Shorter induction period and higher swelling rates were gained at higher temperature.