AbstractStress relaxation modulus data,Er(t), have been determined between −70 and +170°C on blends of three samples of poly(vinyl chloride) of different molecular weights with di‐2‐ethylhexyl adipate, di‐2‐ethylhexyl phthalate, epoxidized soybean oil, and a poly(propyl adipate), respectively. The relaxation modulus‐time–temperature data could be combined into master curves. However, probably owing to the finite contributions of the crystalline phase to the elastic properties, time–temperature superposition is here just marginally valid, and the master curves are only crude, yet still useful approximations. Combination of the present data with the accumulated published information suggests that the viscoelastic properties of plasticized poly(vinyl chloride) are determined primarily by the glass transition temperàture of the plasticizer, the compatibility of polymer and plasticizer, and probably also by the crystallites (as crosslinks). The exact role of the crystallites will remain elusive until the advent of plasticized poly(vinyl chloride) with control
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