study on shape memory of poly(vinyl chloride)/thermoplastic polyester urethane blends

in this research, shape memory effect of polycaprolactone based polyurethane/poly(vinyl chloride) blends in which the pvc weight percentage are 10, 20, 30, 40, 60 and 80 were studied using dma apparatus. the compatibility, tension and dynamic-mechanical properties of these blends have been studied by the authors and this paper specifically deals with the tests results of shape memory effect. the results of tension tests in about 20 percent showed that with increasing pvc content in the blends, recovery rate of temporary shape to permanent shape, the degree of recovery, and the fixity in quantity of temporary shape are improved. therefore, the supplementary shape memory tests were performed on the blend with the highest pvc weight percent (80 percent). in this blend, with increasing tension in thermomechanical cycle, the amount of recovery to earlier shape is decreased due to higher plastic strain. the shape memory tests in consecutive cycles were done on this blend and the behavior of the first cycle was compared with the second and the third cycles. one small tensile handy apparatus was used in order to accomplish shape memory tests in higher tension values and the dma results were registered. in this research the blend with 80 weight percent of pvc as the best shape memory effect was selected.