Plasticizer diffusion as the rate‐determining step in dry blending of poly(vinyl chloride)

Differential thermal analysis has been used to examine the process of dry blending of plasticizer and PVC. The rate of transformation of the glass transition from that of the polymer initially in the cold mix to the glass transition of the blend (blend T g ) has been examined at various temperatures from room temperature to above the polymer T g . The dependence on temperature of this rate of transformation of the observed T g is similar to the temperature dependence of the diffusion of plasticizer into PVC. It is concluded that diffusion of plasticizer into polymer particles is the rate‐determining step in the dry blending of PVC. It also appears that a single mechanism of diffusion is involved both below and above the glass transition of the polymer.