On the dynamic state of plasticized poly(vinyl chloride)

The spin probe technique is suggested to be suitable for the study of polymer‐plasticizer interactions. In this work it was found that the rotational relaxation time (τ) of probe radicals in plasticized poly(vinyl chloride) (PVC) diminishes strongly when the amount of plasticizer is increased. A linear correlation between τ and Young's modulus (G) was observed. This indicated that the microstate considerably influences the mechanical behaviour of the gel. The translational diffusion constant of plasticizer molecules at 25°C was calculated to change from 0.2 times; 10 ‐8 cm 2 /s (PVC weight fraction 0.83) to 4.6 times; 10 ‐8 cm 2 /s, (PVC weight fraction 0.20). These values indicate a high degree of freedom for lateral motion of plasticizer molecules in gels.