Durability of Basalt- and Glass Fiber-Reinforced Polymers: Influence of Internal Stresses, Mass Loss Modeling, and Mechanical/Thermomechanical Properties Under Extreme Cold Climate Exposure.

The durability of basalt fiber-reinforced polymer (BFRP) and glass fiber-reinforced polymer (GFRP) composites was evaluated under extreme cold conditions in Yakutsk (-54 to +36 °C. Laminates (18 layers, epoxy CYD-128) were exposed outdoors for three years. Mechanical testing showed tensile strength and modulus reductions of 22-32% for GFRP, compared with only 6-12% for BFRP. Dynamic mechanical analysis indicated that the glass transition temperature decreased by 11-14 °C in GFRP and 4-6 °C in BFRP. Mass loss kinetics were studied on specimens of different sizes (10 × 10, 20 × 20, and 40 × 40 mm) over 405 days. Seasonal sorption ranged between 0.01-0.19%, while long-term degradation followed a Fickian law with diffusion coefficients of degradation products from 1×10-4 to 0.29mm2/day. A diffusion-based model was proposed, where total mass change is represented as the superposition of reversible sorption and irreversible degradation. The model accurately reproduced experimental trends, highlighting the higher resistance of BFRP. Surface morphology analysis revealed matrix erosion and microcracking on exposed surfaces, with average roughness increasing from 1.61-5.61 µm to 5.86-11.73 µm. Thermomechanical analysis confirmed that BFRP maintained more stable coefficients of linear thermal expansion (-60 to 100 °C) than GFRP, reducing thermally induced stresses during seasonal cycles. These findings demonstrate the superior stability of BFRP compared with GFRP under cold-climate exposure. Comparison of experimental results with mathematical modeling demonstrated that the primary cause of polymer matrix degradation is the action of abrupt internal stresses arising during thermal cycling under extreme cold climate conditions.