Answer:
PET (polyethylene terephthalate) film has limited inherent UV resistance, but its performance can be significantly enhanced through modifications. Here's a concise breakdown:

1. Basic UV Resistance of Pure PET

Unmodified PET film degrades under prolonged UV exposure, leading to yellowing, brittleness, and loss of mechanical strength. This makes it unsuitable for long-term outdoor use without protection.

2. How to Improve UV Resistance

To make PET film UV-resistant, common strategies include:

• UV Absorbers/Stabilizers: Additives like benzotriazoles (e.g., Tinuvin®) or nanoparticles (e.g., modified carbon black) absorb or scatter UV radiation.

• Surface Coatings: UV-curable coatings (e.g., acrylic or polyurethane-based) create a protective barrier without compromising transparency.

• Nanocomposites: Blending PET with nanomaterials (e.g., TiO₂ or ZnO) improves UV blocking while maintaining optical clarity.

3. Applications of UV-Resistant PET Films

• Outdoor Use: Solar panel backsheets, agricultural films, and signage.

• Electronics: Protective films for touchscreens or displays.

• Packaging: UV-stable films for products sensitive to light degradation (e.g., food, pharmaceuticals).

4. Testing & Certification

Modified PET films are validated through accelerated UV aging tests (e.g., ASTM G154) to ensure longevity. High-performance films can withstand 1,000–5,000+ hours of UV exposure with minimal degradation.

Key Takeaway

Standard PET film is not inherently UV-resistant, but engineered variants (with additives, coatings, or composites) offer excellent UV stability. For critical applications (e.g., outdoor or optical uses), always opt for UV-modified PET grades.