Thermal Aging and Degradation of Acrylonitrile Butadiene Rubber and Polyacrylate Rubber
Nitrile rubber (NBR) and Polyacrylate (ACM) are majorly used for sealing applications. The seals are exposed to brake fluid continuously or intermittently over the wide range of temperatures. The material reliability is greatly affected by the temperature and the working fluid. The present study presents the effect on thermal aging behavior of NBR and ACM in brake fluids at temperatures in a range of 80°C to 165°C by measuring the changes in mechanical properties such as tensile strength. The strength of NBR reduces from 17.35 MPa to 13.2 MPa in D3 oil and 17.8 MPa to 13.93 MPa in D4 oil. For ACM rubber the strength reduces from 10.08 MPa to 8.67 MPa in D3 oil and 9.89 MPa to 8.55 MPa in D4 oil. However the hardness increases with increasing of temperature and changes in mass before and after immersion in the brake fluids. TGA shows weight loss for aged and unaged samples of NBR and ACM rubber.
Keywords: Oil seal, Brake fluid, Ageing, Thermal degradation.