Whether it’s a commodity-grade resin or a high-performance plastic designed for use in specific applications, some thermoplastic properties remain consistent across the board.
For instance, the key defining trait of all thermoplastics is they can be heated and reshaped multiple times before they start to lose their strength and integrity. This is due to their cellular structure, which lacks the significant crosslinking found in Thermoset plastics. While thermoplastics and thermoset plastics are both polymers, only thermoplastics can be reheated, remolded, and cooled as needed without causing any chemical changes. By contrast, a thermoset plastic strengthens when heated — and cannot be remolded after the initial forming.
Beyond this key characteristic, general thermoplastic properties include good impact resistance, dimensional stability, chemical resistance, a large number of finishing options, and the ability to remain highly recyclable. While those benefits hold true, in general, for all thermoplastics, the development of high-performance thermoplastics for demanding applications in key industries has offered up additional properties.
Thermoplastics fall into one of three classifications or categories. General Industrial thermoplastics are a standard or commodity-level material typically used for applications that involve temperatures of less than 185°F. Engineered thermoplastics provide some chemical and wear resistance and generally deal with applications having temperatures between 185-300°F. High-Performance thermoplastics meet the most stringent demands found in critical applications and are needed when temperatures exceed 300°F — and upper range coverage that extends to 500°F (260°C).
Let’s examine some of the thermoplastic properties essential to several of the high-performance options typically used in demanding applications today.
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Thermoplastic Properties of High-Performance Materials
Often used as a lighter-weight alternative to metal, high-performance thermoplastic resin can also be mixed with glass fiber, carbon fiber, or other similar materials to improve and enhance the resin’s natural structural properties. These blends are referred to as filled thermoplastics.
At Ensinger Precision Components we have the knowledge, experience, and capability to properly mold and cure high-performance thermoplastics — even reaching the standards required to become an “Approved Molder” of Torlon® for example. We’re equipped to help you get the most out of these specific polymers, mining thermoplastic properties to meet the demands of your application.
Here’s a snapshot of several types of high-performance thermoplastics, what makes each unique, and where they might be best utilized.
PEI — Polyetherimide
PEI brings one of the highest dielectric strengths of any thermoplastic; as a result, it’s often used in high-performance electrical and electronic parts, microwave appliances, and in under-the-hood automotive parts. PEI also exhibits good mechanical strength and rigidity and provides excellent resistance to hydrolysis enabling it to withstand repeated cycles in a steam autoclave. Inherently flame resistant, PEI also boasts broad chemical resistance and displays high creep resistance over a wide temperature range. For more strength and stiffness, PEI can be filled.
PPS — Polyphenylene Sulfide
PPS has outstanding chemical resistance, good electrical properties, excellent flame retardance, a low coefficient of friction, and high transparency to microwave radiation. This combination of properties gives it noted dimensional stability over wide variations of temperatures and moisture levels — opening it to use in applications where alternative fail. High creep resistance makes it well suited for products requiring tight tolerances. Often filled with mineral, glass, or carbon reinforcements, PPS sees use for bearing and pump parts implemented in various corrosive environments.
PI — Polyimide
This thermoplastic provides high strength, dimensional stability, and creep resistance at a broad temperature range, even at the upper ranges available (464°F/240°C). PI is known for excellent sliding characteristics, with properties like low friction wear and a low (and stable) coefficient of friction. These combine for a material that makes for an excellent metal or ceramic replacement in structural parts in industrial equipment, aircraft, and automobiles. When filled, PI has greater strength, fatigue resistance, and wear capability.
PAI — Polyamide-imide
PAI shines with greater compressive and impact strength than most other non-filled high-performance thermoplastics, and its dimensional stability and structural characteristics remain strong even at high temperatures. In fact, PAI shows greater strength at 400°F (200°C) than other specialized thermoplastics demonstrate at room temperature; It can also handle continuous operating temperatures up to 500°F (260°C).
Complete with good wear and chemical resistance, dielectric strength, and electrical insulation, PAI is valued across many demanding industries — including semiconductor & electronics, aerospace, automotive, and oil & gas. For more strength and performance, including thermal expansion properties, PAI can be filled with carbon or glass fibers.
PEEK — Polyetheretherketone
This rigid, opaque (gray) material features a unique combination of properties, which include exceptional chemical, wear, electrical, and temperature resistance, as well as dimensional stability and numerous processing capabilities. Capable of operating in continuous temperatures up to 482°F (250°C) while providing long life and reliability, PEEK fits naturally as a substitute for heavy metal parts, such as components for cars, aircraft, and industrial pumps.
PEEK also provides excellent electrical properties and will not hydrolyze in water. The material’s heat and hydrolysis resistance mean it’s a perfect fit for medical products that need steam sterilization as well. Medical-grade PEEK can endure more than 1,500 cycles with no significant loss to mechanical properties, no discoloration, and no calcification.
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Get Expert Guidance Across the High-Performance Spectrum
Thermoplastic properties are needed in part manufacturing and are rising in demand as a replacement for ceramics, composites, and metal. The benefits make them an ideal solution for challenging applications but also demand special care and expertise when it comes to injection molding with these materials.
With more than 80 years of experience in high-performance thermoplastics, Ensinger Precision Components designs and manufactures solutions that exceed your requirements and expectations. Our complete suite of plastic manufacturing capabilities means we’re equipped to handle any challenge and have the experience needed to properly work with any class of thermoplastics.