Evaluation of New ACM Polymers in Sealing Applications Using Advances in Compressive Stress Relaxation Test Measurements: Part 2

Compressive Stress Relaxation (CSR) testing is challenging due to the different sample geometries, fixtures, aeration, and temperature cycles. Ageing environments such as hot air, static fluids, and aerated fluids contribute significantly to this challenge. ASTM and Original Equipment Manufacturer (OEM) standards allow a fixture two hours to equilibrate after immersion in ageing medium before testing. Experience has shown that the sample may not be at room temperature thus leading to possible errors in force readings. The focus of this paper is to conduct thermal cycle testing on typical rubber gasket compounds in order to determine their properties in such environments. Various thermal cycling methods were performed in order to determine the influence on the compound properties. Tests were conducted using compressive stress relaxation (CSR) with Wykeham-Farrance (W-F) intermittent fixture and Elastocon continuous tester, compression set (C/S), and modulus readings in air environments using different thermal conditions. The compounds used in this study were based on Polyacrylic (ACM), Ethylene Acrylic (AEM), and Hydrogenated Nitrile Butadiene Rubber (HNBR) polymers.