Assessment of failures of nitrile rubber vulcanizates in rapid gas decompression (RGD) testing: Effect of physico-mechanical properties

摘要

Rapid gas decompression (RGD) test is used to evaluate structural failures such as bubbles, blisters, internal and external cracks in rubber vulcanizates exposed to gas environment under high pressure and high temperature (HPHT) conditions. Physico-mechanical properties of vulcanizates may greatly affect the RGD resistance of rubber products. In this study, effect of the most important physico-mechanical properties such as hardness, modulus, elongation at break, tensile strength, tear strength, compression set and crosslink density of nitrile rubber (NBR) samples cured by different sulfur curing systems including conventional system (CV), semi-efficient system (SEV) and efficient system (EV) on RGD resistance has been investigated. Results showed that the type of sulfur curing system and resultant physico-mechanical properties had pronounced effects on RGD resistance. The NBR rubber samples prepared by CV system exhibited highest failures under RGD testing. Moreover, by increasing crosslink density, hardness and modulus of NBR vulcanizates, the internal cracks were increased during RGD test. Furthermore, the RGD resistance was improved at higher tear strength of rubber samples. Also, lower compression set specially in CV curing system and higher tensile strength of NBR samples lead to less structural failures.