EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

HNBR elastomers are used widely in the oil and gas industry due to their high resistance to chemicals and high temperatures. This characteristic of HNBR is the result of nitrogen bonding and a low degree of unsaturation in the elastomer backbone which make these materials distinguished from other elastomer types. However, they are still aged in extreme environments of high temperature and high pressure. This study investigated how elevated temperatures and time affected the ageing of HNBR compounds and studies the underlying mechanisms with ageing. Differential scanning calorimetry analysis (DSC) confirmed increased glass transition temperature for aged specimens and from Fourier Transform IR spectra, additional crosslinking in the aged specimens were identified. However, FTIR and DSC analysis for specimens aged at temperatures above 150°C confirmed that chain scission reactions overtake crosslinking which is linked to crosslink saturation and high activation energy in the system that facilitates chain scission reactions. Furthermore, optical micrographs of the surface and cross-section of aged specimens showed inhomogeneous ageing is derived with high temperature rather than the longer ageing time. This phenomenon occurs when oxygen is consumed on the surface at a higher rate than through the thickness accelerates with the size of the specimens and needs to be considered in predicting the long-term behaviour of elastomer products in service.