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

Area of Science:

• Materials Science
• Polymer Chemistry
• Mechanical Engineering

Background:

• Traditional models like Tobolsky's dual network theory are limited for complex aging in filled elastomers.
• Existing models often fail to accurately predict rubber behavior under chemical aging at fixed strains.

Purpose of the Study:

• To develop and validate a new predictive model for rubber behavior during chemical aging at fixed strains.
• To address the shortcomings of existing models when applied to filled rubber composites.

Main Methods:

• Validation using carbon black-filled nitrile butadiene rubber aged in air at 125 °C.
• Testing of uniaxial tensile samples aged at various strains (0-30%) for 24-72 hours.
• Measurement of permanent set, stress-strain behavior via Instron testing, and cross-link density via equilibrium swelling.

Main Results:

• The new model demonstrates improved accuracy in predicting stress-strain behavior, especially at higher strains.
• The model provides more reliable estimations of chain scission and cross-linking phenomena post-aging.
• Validation confirmed the model's effectiveness for aged carbon black-filled nitrile butadiene rubber.

Conclusions:

• The developed model offers a more accurate and reliable approach to predicting the behavior of aged rubber composites.
• This work provides a significant advancement over existing theories for modeling complex elastomer aging.
• The findings are crucial for understanding and predicting material degradation in demanding applications.