Stress–thermal oxidative aging behavior of hydrogenated nitrile rubber seals

Abstract

The long-term thermal oxidative aging behavior of uncompressed and compressed hydrogenated nitrile rubber seals was studied in terms of the weight loss, chemical structure, crosslinking density, compression set, fracture morphology, and mechanical properties. It was found that weight loss of the uncompressed seals was more than that of the compressed seals due to restricted mobility of additives and molecular chains under compression. The ATR-FTIR results showed that hydroxyl groups and carbonyl groups both were formed under the uncompressed and compressed states, whereas only the generation of amide groups was observed under the uncompressed state. Additionally, crosslinking reactions dominated throughout the aging process, but stress-induced and oxidationinduced chain scissions occurred and competed with crosslinking during subsequent middle and later stages of aging at 110 C. Compression set of the compressed seals implied the formation of a denser network structure. The surface damage of the uncompressed seals gradually turned more serious and inhomogeneous than that of the compressed seals. Mechanical properties of the uncompressed and compressed seals showed a similar variation tendency with exposure time and degraded more seriously at higher temperatures. The TGA results indicated that the aging conditions (elevated temperature and compressive stress) did not significantly affect the thermal stability of the rubber seals.

The Effect of Network Structure on Compressive Fatigue Behavior of Unfilled Styrene‐Butadiene Rubber

“…e crosslinking densities of vulcanizates were determined by the Flory-Rehner equation shown in equation (1). To achieve their swollen equilibrium, weighed samples were, respectively, immersed in toluene at room temperature for 72 hours.…”

“…Rubber materials are widely used in industrial fields because of their high elasticity and excellent damping properties [1,2]. However, fatigue failures that are common in rubber components remain a key issue.…”

Compressive Fatigue Behavior of Gum and Filled SBR Vulcanizates

“…Therefore, for vibrational dampers and shock absorbers, the performance of fatigue resistance under compressive conditions is of great importance. Nowadays, few research studies focus on the compressive fatigue mechanism of styrene-butadiene rubber (SBR), which is a kind of non-crystallizable rubber and contains excellent damping behavior over a wide range of temperatures and frequencies [ 1 , 2 , 3 ]. As it is very different from natural rubber (NR), the fatigue mechanism of SBR is not dependent on the strain crystallization, so that it is very suitable for studying the fatigue mechanism [ 4 , 5 , 6 , 7 ].…”

Multiscale simulation on dynamic friction behavior of cylinder sealing rings under hydrothermal aging

“…Different media had been introduced to several tests in order to find the aging behaviors of NBR. The epoxidation degradation activation energy value of a NBR was measured to be 82 kJ/mol, and it had been proved that the aging conditions (elevated temperature and compressive stress) did not significantly affect the thermal stability of the rubber seals 8–10 . Results indicated that the friction coefficient increased but the wear volume decreased with aging time was conducted by an experimental study 11,12 of a NBR steel pair, and the influence of shedding light was also considered.…”