Polyetherimide (PEI)
PEI provides high temperature resistance, strong mechanical performance, and excellent electrical insulation for aerospace, medical, and electrical applications.
Select a form factor to view real-time inventory, pricing, and custom cut-to-size options.
| Short Description | Color | Diameter | Length | Stock | Price | Add to quote |
|---|---|---|---|---|---|---|
| Ultem 1000 (PEI) - 0.250" dia x 120 Black Rod | Black | 0.250″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.250" dia x 120 Natural Rod | Natural | 0.250″ | 120″ | Out of stock | Contact | |
| Ultem GF30 (PEI GF30) - 0.250" dia x 120 Natural Rod | Natural | 0.250″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.375" dia x 120 Black Rod | Black | 0.375″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.375" dia x 120 Natural Rod | Natural | 0.375″ | 120″ | Out of stock | Contact | |
| Ultem GF30 (PEI GF30) - 0.375" dia x 120 Natural Rod | Natural | 0.375″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.500" dia x 120 Black Rod | Black | 0.500″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.500" dia x 120 Natural Rod | Natural | 0.500″ | 120″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.500" dia x 48 Black Rod | Black | 0.500″ | 48″ | Out of stock | Contact | |
| Ultem 1000 (PEI) - 0.500" dia x 96 Black Rod | Black | 0.500″ | 96″ | Out of stock | Contact |
Material Overview
Polyetherimide (PEI) is a high-performance amorphous thermoplastic that combines exceptional heat resistance, high mechanical strength, and outstanding electrical insulation in a single material. PEI sheet and rod stock is specified across aerospace, medical device, semiconductor, and electrical insulation applications where standard engineering plastics cannot sustain performance under thermal and electrical stress. Its amber color, inherent flame resistance, and broad chemical compatibility make it a versatile baseline material for precision-machined components. Ready Plastics stocks PEI plastic in standard sheet and rod sizes for immediate fabrication.
The mechanical profile of PEI is well suited to structural applications operating at elevated temperatures. Tensile strength reaches 15,250 psi with a compressive stress of 22,000 psi at 10% strain and a Rockwell hardness of R126. Tensile modulus is 493,000 psi, providing the rigidity needed for close-tolerance components. Density is just 0.046 lb/in³ — a meaningful advantage in weight-sensitive aerospace and defense assemblies. Continuous service temperature extends to 340°F (170°C) with short-term ratings of 390°F (195°C), backed by a heat deflection temperature of 375°F (190°C) at 264 psi. These values support use in applications that cycle between ambient and elevated temperatures without dimensional drift.
Electrical performance and flame resistance. PEI provides dielectric strength of 685 V/mil, volume resistivity exceeding 10¹⁴ Ω·cm, and surface resistivity above 10¹³ Ω — properties that make it a reliable insulator for connectors, circuit board supports, and high-voltage housings. The material carries a UL 94 V-0 flammability rating at both 3 mm and 6 mm thickness with inherent flame resistance that requires no additives, generating low smoke during combustion. Water absorption is low at 0.26% over 24 hours immersion, ensuring electrical properties and dimensions remain stable in humid environments. The coefficient of thermal expansion is 25 µin/in/°F, supporting tight-tolerance assemblies that operate across wide temperature ranges.
Grade selection within the PEI family. Unfilled PEI is the preferred starting point for general high-temperature service — it offers the best machinability and impact toughness in the family. For cleanroom and contamination-sensitive work, PEI CRS provides the same baseline performance with reduced particulate generation. When stiffness, creep resistance, or dimensional stability under load must be increased, Ready Plastics offers three glass-fiber-reinforced grades: PEI GF10 (10% glass fiber) for a moderate reinforcement step, PEI GF20 (20% glass fiber) for higher rigidity, and PEI GF30 (30% glass fiber) for maximum stiffness in structural applications. All grades share the same high-temperature capability and UL 94 V-0 flame resistance of the polyetherimide family.
Technical Specifications
Typical values at 23°C / 50% RH. Values are nominal and not guaranteed; refer to lot-specific certificates of conformance for production parts.
Frequently Asked Questions
PEI (polyetherimide) is a high-performance amorphous thermoplastic known for its combination of high tensile strength (15,250 psi), continuous service temperature up to 340°F (170°C), UL 94 V-0 flame resistance, and excellent electrical insulation (685 V/mil dielectric strength). It is widely used in aerospace brackets, medical instruments, semiconductor fixtures, and electrical connectors where standard engineering plastics cannot sustain performance.
Unfilled PEI offers the best machinability, toughness, and electrical performance in the family and is the standard choice for most precision-machined parts. Glass-fiber grades (GF10, GF20, GF30) trade some toughness and machinability for significantly higher stiffness, lower thermal expansion, and better resistance to creep under sustained load — making them better suited for structural or dimensionally critical components at elevated temperatures.
Ready Plastics stocks PEI in sheet and rod form in a range of standard sizes. Contact us or download the datasheet for current thickness and diameter availability. Custom profiles and near-net-shape blanks can be cut to order.
Yes. PEI machines cleanly on conventional CNC mills, lathes, and drills using standard carbide tooling. Its low moisture absorption and dimensional stability allow tight-tolerance parts without special fixturing. Conventional cutting speeds apply; sharp tooling and light finishing cuts are recommended for critical surfaces.
PEI operates at higher continuous temperatures (340°F vs. roughly 300–320°F for PSU) and offers superior electrical insulation. PSU and PPSU have better hydrolytic stability and toughness, making them preferred for steam-sterilized medical devices. Choose PEI where high-temperature performance and electrical insulation are the primary requirements.
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