Improved Dual Network Model for Aging of Rubber Composites under Set Strains

A newmodel is presented to predict rubber behavior duringchemicalaging at fixed strains. The model is validated using a carbon black-fillednitrile butadiene rubber aged in air at 125 & DEG;C. The model improvesupon Tobolsky's dual network theory, designed for unfilledelastomers undergoing conventional aging but which has also oftenbeen used in rubber composites undergoing more complex aging scenarios.This work explores the shortcomings of the original model and demonstrateshow the new model overcomes them. The model was validated using uniaxialtensile samples aged at 125 & DEG;C for 24-72 h at strainsfrom 0-30%. The permanent set was measured, and the sampleswere tested on an Instron uniaxial test machine after aging. The cross-linkdensity was estimated by equilibrium swelling. Results show that thenew model more accurately models the stress-strain behaviorto higher strains and provides more reliable estimates of chain scissionand cross-linking after aging.

Automated summary

A new model is proposed to predict the behavior of rubber during chemical aging with fixed strains. The model is validated using carbon black-filled nitrile butadiene rubber aged in air at 125°C. This study addresses the limitations of the original model and demonstrates the improvements in the new model's ability to accurately model stress-strain behavior and estimate chain scission and cross-linking after aging.