What are the effects of prolonged exposure to high-altitude UV radiation on composites?

Prolonged exposure to high-altitude UV radiation significantly impacts composite materials, particularly those used in aerospace, automotive, and outdoor structures. UV rays cause photodegradation, breaking down polymer matrices and weakening fiber-matrix bonds. This leads to reduced mechanical strength, discoloration, and surface cracking.

Key effects include:

1. Polymer Degradation: UV radiation breaks chemical bonds in resin matrices, causing brittleness.

2. Fiber Damage: Glass and carbon fibers may experience interfacial weakening, reducing load-bearing capacity.

3. Oxidation: Accelerated aging occurs due to UV-induced oxidative reactions.

Mitigation strategies involve UV-resistant coatings, additives like stabilizers, and selecting inherently UV-stable materials (e.g., aramid fibers). Understanding these effects is critical for designing durable composites in high-altitude environments.