Polyetherimide (PEI)[2]

Updated: 2026-09-15

Overview

Polyetherimide (PEI) is an amorphous, high-performance thermoplastic known for its exceptional thermal and mechanical properties. Developed in the 1980s, PEI is part of the polyimide family and is commonly marketed under the trade name Ultem. Its unique combination of strength, flame retardancy, and chemical resistance makes it a preferred material for demanding industrial applications. PEI is synthesized through a condensation reaction of bisphenol A dianhydride and m-phenylenediamine. The resulting polymer exhibits high glass transition temperatures and maintains structural integrity under extreme conditions. These characteristics have led to its widespread adoption in aerospace, automotive, and electronics industries.

Physical and Chemical Properties

PEI is characterized by its amber-to-transparent appearance and high density (1.27 g/cm³). It has a melting point range of 215–220 °C and can withstand continuous use at temperatures up to 170 °C. The material is inherently flame retardant, achieving a UL94 V-0 rating without additives. Chemically, PEI is resistant to most acids, bases, and hydrocarbons, though it may degrade in strong alkalies or polar solvents like N-methyl-2-pyrrolidone (NMP). Its electrical insulation properties remain stable across a wide temperature range, making it ideal for electronic components.

Main Applications

In aerospace, PEI is used for interior components, ducting, and structural parts due to its lightweight and fire-resistant properties. The automotive industry utilizes it for under-the-hood components, sensor housings, and connectors where thermal stability is critical. The electronics sector employs PEI in circuit boards, connectors, and insulating films. Medical applications include surgical instruments and sterilization trays, benefiting from PEI's biocompatibility and steam autoclave resistance. Recent innovations include 3D printing filaments for high-temperature prototyping.

Safety and Storage

PEI is generally considered safe for industrial use but requires standard polymer handling precautions. Dust inhalation should be avoided through proper ventilation or respiratory protection. The material emits minimal smoke when burned but may release trace amounts of carbon monoxide and nitrogen oxides. For storage, PEI pellets should be kept in sealed containers at room temperature (below 40 °C) with less than 50% relative humidity. Prolonged exposure to moisture can lead to hydrolytic degradation during high-temperature processing. Suppliers typically recommend a shelf life of 12 months under optimal conditions.

B2B Procurement Guide

When sourcing PEI, buyers should specify required grades based on application needs—standard, glass-filled (10–40% for enhanced stiffness), or flame-retardant variants. Key certifications to verify include FDA compliance for food-contact uses and UL recognition for electrical applications. Lead times vary by supplier but typically range from 4–8 weeks for standard grades. Bulk purchases (500+ kg) often qualify for 5–15% discounts. For prototype development, consider purchasing small quantities from distributors with cut-to-order services. Always request material data sheets (MDS) and processing guidelines from manufacturers.