Influence of aging medium on recovery behaviors of CR/NR composite from circular deformation

Abstract

This study examined the recovery behavior from the circular deformation of a thermally aged CR/NR composite. A linear sample of a rubber vulcanizate was made into circular form by fixing both ends of the sample with a pin and aging it thermally in air and distilled water. The recovery increased with the time after removal from circular deformation. The recovery decreased with increasing aging temperature and time. Recovery of the sample aged in air was smaller for long measurement times than that of the sample aged in distilled water. The difference in the recovery behavior of the samples aged in air and distilled water can be explained by changes in the crosslinking density and the annealing effect of the aging medium. The instantaneous recovery was obtained by extrapolating the linear recovery variations. They also showed a good linear relationship with the aging time.The recovery behavior at ambient temperature could be predicted using the experimental results of the accelerated thermal aging. In terms of the instantaneous time, it was predicted that the service lifetime of the sample aged in air at ambient temperature would be much longer than the sample aged in water.

Recovery Behaviors of Natural Rubber Composites Thermally Aged in Altering Medium Systems of Air and Water

“…In general, recovery of a rubber composite aged in air is greater than that aged in water due to the annealing effect by water. 18,22 At the first aging day of 10 days, recovery of the sample aged in the A®W altering system is greater than that aged in the W®A one. Both the altering aging medium systems have the same time periods of 5 days in air and 5 days in water.…”

Influence of Aging Media and Filler System on Recovery Behaviors of Natural Rubber Composites

“…Parameters affecting to permanently deform a rubber vulcanizate are the rearrangements of rubber chains and fillers and the change of crosslink density by aging. 2,[8][9][10][11][12][13][14]18 When a rubber article is deformed, the rubber chains are strained and their microstructures are changed. If the strained polymer chains are settled in the deformed state by rearrangement and stabilization, degree of the permanent deformation of the rubber article will increase and the recovery behaviors will also be influenced.…”