Protective Cases in Heat, Cold and Sunlight: Temperature and UV Performance
Plastic case shells have three separate limits: short-term heat (softening), long-term cold (embrittlement) and UV dose (surface degradation). Typical service ranges are −20 to +60 °C for standard ABS and PP, −40 to +80/90 °C for cold-compounded PP or rotomolded PE, and effectively no low-temperature limit for aluminum. Outdoors, UV-stabilized compounds and dark colors age far slower than unstabilized bright plastics.
§01Heat: short-term vs continuous
| Material | Continuous service (typical) | Short-term peak | Cold limit (typical) |
|---|---|---|---|
| ABS | 70–85 °C | ≈95 °C | ≈−20 °C |
| PP (standard homo/copolymer) | 60–80 °C | ≈100 °C | −20 °C |
| PP/PE cold compounds | 80–90 °C | ≈110 °C | −40 °C |
| Rotomolded LLDPE | 70–90 °C | ≈100 °C | −40 °C and below |
| Aluminum | >150 °C | — | no embrittlement |
§02UV: the quiet killer
UV breaks polymer chains at the surface, causing chalking, fading and micro-cracking that eventually reach the gasket groove. Three defenses matter: UV stabilizers (HALS and UV absorbers) in the compound, carbon black pigment — which is why black and dark-grey cases dominate outdoor fleets — and wall thickness, since degradation starts at the surface.
- Stabilized black PP/PE routinely serves 5–10+ years outdoors.
- Bright colors can be stabilized well, but pigment choice is narrower; ask for weathering test data (e.g., xenon-arc exposure hours) rather than promises.
- Where a case lives its whole life indoors, UV is irrelevant — do not pay for it, and prioritize impact and gasket performance instead.
§03Thermal cycling
Repeated hot–cold cycles age gaskets and loosen screws faster than steady temperatures. For equipment that lives in vehicles or aircraft holds, thermal-shock testing (MIL-STD-810 Method 503) on the assembled case is a more honest specification than any single temperature extreme.