Research on the Thermal Aging Performance of a GAP-Based Polyurethane Elastomer

Area of Science:

• Materials Science
• Polymer Chemistry
• Propellant Technology

Background:

• Glycidyl azide polymer (GAP)-based polyurethane serves as a critical elastomeric matrix in high-energy, low-smoke, and insensitive solid propellants.
• Aging-induced structural and property changes in GAP elastomers can degrade propellant performance and pose safety risks.

Purpose of the Study:

• To investigate the aging mechanism of GAP elastomers under accelerated thermal conditions.
• To correlate microstructural evolution with macroscopic property changes during aging.
• To identify key chemical bonds and network structures susceptible to degradation.

Main Methods:

• High-temperature accelerated aging experiment at 70 °C.
• Microstructural analysis using Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR).
• Macroscopic property evaluation via hardness testing and uniaxial tensile tests.

Main Results:

• Thermal aging is a coupled process involving multiple chemical reactions, affecting azide groups, urethane groups, and ether bonds.
• Crosslinking density initially increases and then decreases during aging.
• Macroscopic properties exhibit segmented changes corresponding to three distinct aging stages: post-curing, network initiation of breakdown, and network destruction.

Conclusions:

• Microstructural and macroscopic changes during GAP elastomer aging are consistent.
• The identified aging stages provide a framework for understanding propellant performance deterioration.
• This research is vital for improving the aging mechanism understanding and extending the storage life of GAP propellants.