Why Polyimides Win Above 500°F

When customers ask for plastics that can survive high heat, there are several datasheet properties that provide a useful starting point. We covered these fundamentals in our guide to two properties that define high-temperature plastics, and they can help frame the discussion around ultra-high-performance materials like polyimides (PI).

Navigating High-Temperature Choices

As temperature rises, the set of polymers you can use shrinks. The best high-performance materials maintain strength and stiffness while resisting oxidative degradation. The chart below shows stiffness retention reference values for six Mitsubishi Chemical Group (MCG) high-temperature materials measured using Dynamic Mechanical Analysis (DMA). While all offer elevated thermal capabilities, the Duratron™ PI grades stand out as temperatures approach and exceed 500°F (260°C).

At room temperature, Ketron™ polyetheretherketone (PEEK) and Duratron™ polyamide-imide (PAI) grades begin with similar stiffness. As temperature rises, Ketron™ PEEK softens sharply around 300°F (150°C)—its glass transition temperature—making it less suitable for sustained high-heat applications. Duratron™ PAI maintains higher stiffness across a wider temperature window, but begins to decline as temperatures approach 480°F (~250°C). Techtron™ polyphenylene sulfide (PPS), while useful in elevated-heat environments, shows an earlier decline in stiffness relative to the others.

In contrast, Duratron™ PI grades retain stiffness further into extreme temperature territory, demonstrating why PI are often chosen for continuous service beyond the upper limits of melt-processable materials like PAI and PEEK.

This temperature-dependent performance profile highlights the sweet spot for Duratron™ PI: applications operating above 480°F (~250°C) where long-term strength and dimensional stability are critical.