Study on the modification of TPU/PVC/NBR blends

摘要

The mechanical properties and morphology of thermoplastic polyurethane/polyvinyl chlorideitrile rubber (TPU/PVC/NBR) blends were studied. Most attention had been given to the effects of polar rubbers (nitrile rubber and chloroprene rubber) and nonpolar rubbers (butadiene rubber, styrene-butadiene rubber and ethylene-propylene diene rubber) on blending with TPU and PVC. Experimental results showed that mechanical properties of polar rubber/TPU/PVC blends were better than those of nonpolar rub-ber/TPU/PVC blends under the same condition. In the series of nitrile rubbers, two types, NBR-3604 and N-41, were superior to the other types of NBR blended with TPU and PVC in mechanical properties. In the TPU/PVC/NBR blending system, with the content of NBR increased and TPU decreased, NBR had an effect on substituting TPU in the blends. Moreover, degree of polymerization of PVC also affected properties of the blends. The strength of the blends was enhanced as degree of polymerization of PVC increased, but some of the properties of the blends with a high degree of polymerization PVC (DP=2 500, 3 000) got worse. TPU/PVC/NBR blending systems were crosslinked partially attributed to the DCP added. The results proved that elongation at break of the blends was improved and its permanent set reduced. The scanning electron microscopy (SEM) micrographs showed that the polar nitrile rubber blended with TPU and PVC was more compatible than that of nonpolar rubbers.