Standard polypropylene (PP) honeycomb core has a typical continuous service temperature range of -40°C to +80°C. Within this range, its mechanical properties remain stable.
- Low-Temperature Performance: PP retains good toughness at low temperatures, with a very low brittle point (typically below -20°C), so it remains usable at -40°C. Low temperatures primarily affect the adhesive; ensure the adhesive used does not become brittle.
- High-Temperature Effects: Temperature is a key factor affecting PP honeycomb performance. As temperature approaches or exceeds PP’s glass transition temperature and heat deflection temperature:
- Stiffness Decreases Significantly: The core’s compressive and shear moduli drop sharply with increasing temperature, leading to reduced flexural stiffness of the entire sandwich structure.
- Load-Bearing Capacity Weakens: The core becomes more prone to buckling and creep (slow deformation) at high temperatures.
- Risk to Dimensional Stability: Long-term exposure near the upper limit or short-term exceedance may cause irreversible deformation.
- Short-Term Peaks: For short-term exposure (minutes to hours), such as during composite curing, it can withstand 100-110°C. Time and pressure must be controlled.
- Solutions: For applications requiring higher temperature resistance (e.g., near engines), consider:
- Heat-Modified PP Honeycomb: Increased heat deflection temperature via copolymerization or heat stabilizers.
- GMT Honeycomb or Long Glass Fiber Reinforced PP Honeycomb: Glass fiber addition significantly improves heat resistance and dimensional stability at high temperatures, allowing service temperatures above 120°C.
- Alternative Material Systems: Consider higher-temperature cores like PET foam, aramid paper honeycomb, or aluminum honeycomb.
