Thermal analyses of epoxidized soybean oil (ESO) were conducted and showed that it was stable up to temperatures as high as 240-260 degrees C in air-free environment. The solubility and transport characteristics of ESO in poly(vinylchloride) (PVC) were also investigated under various conditions. The absorption study showed that the resin had a void volume of approximate to 0.3 cm(3)/g. Furthermore, ESO was found to be sufficiently soluble in the PVC matrix to function as an effective plasticizer, with equilibrium solubility of 72 g/100 g PVC at 80 degrees C and 163 g/100 g PVC at 120 degrees C. The absorption of ESO in PVC grains was a three step process comprising induction, swelling, and saturation periods. Torque rheometer studies showed that higher mixer temperature and/or speed facilitated uptake of plasticizer in PVC and ultimate fusion. Migration studies of plasticized and stabilized PVC compositions showed no change in mass at 40 degrees C, but increasingly greater mass loss as the temperature was raised up to 120 degrees C. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers