Dynamic Viscoelasticity of Various Polyvinylchloride-Resins at Low Temperatures

Abstract

Dynamic viscoelasticity of polyvinylchloride (PVC) resins is measured at -150°C-+50°Cby the vibrating reed method (100-200 c/s). Viscoelasticity of these specimens is also measured at 15°C by the free torsional vibration method (0.05-1.7c/s). The samples are homopolymers plasticized by either dioctyl adipate (DOA) or tricresyl phosphate (TCP), copolymers of VC and vinyl acetate (VAc), and polyblend of PVC and PVAc.
It is concluded that;(1) the β transition of PVC is not due to the movement of the end group of the molecules
(2) the flexibility of PVC resins at low temperatures is due to the shape of the a absorption and the temperature at which this absorption appears and it does not depend on the, βabsorption.
(3) plasticizing mechanism of the plasticizer is different from that due to the copolymerization.Addition of the plasticizer shifts the foot of a peak to lower temperature, while the copolymerization results in the appearance of a new, characteristic peak at 30°C. The new peak seems to be due to the micro-Brownian movement of the segments of VAc only, which are more flexible than VC chains. 4′ Department of Polymer Science, Osaka University (Nakanoshima, Kita-ku, Osaka)