Performance Of Environmentally Friendly Plasticizers For Suspension Polymerization Poly (Vinyl Chloride)

Time-temperature characteristics of plasticizer absorption by suspension polymerization poly(vinyl chloride) (S-PVC) was studied by determining the absorption quantities of 7 Environmentally friendly plasticizer under various conditions of time and temperature. The process and mechanism of plasticizer absorption were discussed according to the morphology of S-PVC grains with different absorption conditions characterized by scanning electron microscopy (SEM). The synergy effect of plasticizer blends was investigated with the basic components of epoxy soybean oil (ESO). The mechanical properties, anti-aging properties, plasticizing efficiency, and electrical properties of the flexible PVC samples prepared with ESO as the secondary plasticizer were comparatively analyzed. The results showed that plasticizer absorption by S-PVC was a time-related unsteady process which was comprised of four periods, named "First Induction Period", "First Swelling Period", "Second Induction Period", and "Second Swelling Period". At the "First Induction Period", the grooves of PVC grains were slowly wetted and spread in 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 reached; and at the "Second Swelling Period", the space between molecular chains were rapidly occupied and swelled by plasticizers. Synergy effect of plasticizer blends was obvious when their polarity was close, and the effect could make the time of "First Induction Period shorten or the uptake rate of "First Swelling Period" and "Second Swelling Period" increase under some proportion, and especially strong at "Second Swelling Period". Plasticizers migration was mainly controlled by their compatibility with PVC when temperature was below or near the glass transition temperature (Tg), the mass loss on the one hand was approximately linear with time; on the other hand plasticizers migration was retarded with the degradation of PVC at the case of temperature was above Tg. Vif and TOTM showed perfect in comprehensive performance in the basic formulation with ESO as the secondary plasticizer, LPlas-2 and Flep were also good plasticizers, but LPlas-1 and Pac were poor.