抄録
Mechanical properties of unplasticized polyvinylchloride under tension and compression were reported in this paper. The following results were obtained:
(1) This material shows a distinct yield point and the strain corresponding to this point becomes larger as the testing temperature becomes low, and reaches the maximum value at about 0°-10°C.
(2) The stress-strain curve up to the yield point is affected remarkably by the testing temperature and strain velocity which also greatly affect the total elongation at the breaking point.
(3) Regarding the process of cross-necking, a peculiar type of deformation is observed as shown in Fig. 12.
(4) A secondary test was made at a different temperature on a specimen stretched primarily at a certain temperature and the mechanical properties were examined.
a) Properties of the specimen streched previously at a high temperature up to the yield point are in the second low temperature test not affected by the previous treatment.
b) When the primary elongation at high temperature is greater than the breaking elongation at low temperature, the specimen shows no new necking deformation in the second test (low temperature test) and is fractured in a brittle manner.
c) On the contrary, the specimen stretched previously at low temperature over the yield point, shows in the second stretching at high temperature no yield point and deforms according to its original stress-plastic deformation curve.
