Why unfilled PEI holds the electrical parts niche
Every glass- or carbon-filled engineering plastic trades something away for strength: filler changes dimensional behavior, surface finish, and — critically for electrical engineers — dielectric performance. PEI (polyetherimide, commercially ULTEM) unfilled grade 1000 is the baseline configuration that keeps the full electrical property set intact while still delivering 170°C continuous service. For connectors, switch components, circuit board carriers and insulators, that combination is the reason the grade remains one of the most specified amorphous thermoplastics in electrical and electronics design.
The market context supports investing in the specification. The global PEI market was valued at USD 706.20 million in 2025 and is projected to reach USD 967.56 million by 2030, a 6.5% CAGR (Mordor Intelligence, as cited by the source). Independent estimates bracket the same trajectory: IMARC Group projects USD 735.5 million (2025) to USD 1,224.9 million (2034), while Future Market Insights models USD 0.8 billion (2025) to USD 1.3 billion (2035). The spread between research houses is normal for a specialty resin category; the direction is not in dispute.
Where the demand sits
Sector share data for PEI (Staticker, 2026, as cited) shows demand concentrated exactly where unfilled grades matter most:
| Sector | Share of demand | Primary driver | Key requirement |
|---|---|---|---|
| Aerospace | 28% | Weight reduction, fuel efficiency | Flame retardancy, mechanical strength |
| Electronics & Electrical | 24% | Miniaturization, 5G infrastructure | High dielectric strength, thermal stability |
| Automotive | 18% | Electric vehicles, lightweighting | Heat resistance, chemical resistance |
| Industrial | 18% | Harsh environment applications | Chemical resistance, dimensional stability |
| Medical | 12% | Sterilizable devices, implants | Biocompatibility, steam autoclave resistance |
Electronics and aerospace together account for over 50% of global PEI demand, and the source identifies the Asia-Pacific region as both the largest and fastest-growing market for polyetherimide — relevant to any buyer weighing regional supply against export certification needs.
The specification that drives selection
Unfilled Ultem 1000's headline numbers, per the source's compiled datasheet values:
| Property | Value |
|---|---|
| Tensile strength | 15,200 psi (101 MPa) at room temperature |
| Flexural modulus | 480,000 psi (3,300 MPa) |
| Heat deflection temperature | 392°F (200°C) at 264 psi |
| Continuous service temperature | 340°F (170°C) |
| Short-term exposure limit | 400°F (204°C) |
| Dielectric strength | 830 V/mil |
| Dielectric constant | 3.15 at 1 MHz |
| Flame rating | UL94 V-0 at 0.060 inch thickness |
| Specific gravity | 1.27 g/cm³ |
Two of these numbers decide most quotes. The dielectric strength of 830 V/mil with a dielectric constant of 3.15 at 1 MHz keeps electrical performance stable across a wide frequency and temperature range — the property connectors and switches live on. And the 170°C continuous rating with UL94 V-0 inherent flame retardancy (no additive package required) covers safety-critical components where a brominated or phosphorus flame-retardant system would complicate regulatory documentation.
The grade ladder: when to leave unfilled
Unfilled is the default, but the ULTEM family offers reinforced steps when structural loads dominate:
- Ultem 1000 (unfilled) — best electrical properties, lowest thermal expansion; the default for connectors, insulators, and electrical housings.
- Ultem 2200 (20% glass) — balanced strength/toughness with improved dimensional stability for structural electrical parts.
- Ultem 2300 (30% glass) — enhanced strength and stiffness, UL94 V-0 retained, but at roughly +25-35% cost, with reduced electrical properties and a visible fiber pattern. The source positions it for structural components, aerospace parts and high-load applications.
The selection logic is straightforward: if the part's binding constraint is dielectric performance, dimensional fidelity or surface finish, stay unfilled; if it is load or stiffness, step up the glass content and re-verify the electrical spec against your operating voltage and frequency.
What procurement teams actually check
The source's analysis of buyer behavior on B2B platforms highlights documentation as the first filter. Buyers in regulated industries (aerospace, medical) routinely require:
- Complete material data sheets with the full property set — not a one-page summary.
- Certification documents — UL, FDA, ISO and aerospace qualifications as applicable to the end use.
- Batch traceability and quality control records.
- Processing guidelines for the buyer's own molding operation.
Pricing expectations follow the same transparency pattern: clear MOQ specifications, tiered pricing in the listing, and transparency about additives or regrind policy. In a premium resin category, a quote that arrives without the documentation package reads as a quote that cannot be verified.
Bottom line for 2026 sourcing
PEI Ultem 1000 occupies a defensible position: the electrical property set of an unfilled amorphous thermoplastic with a 170°C continuous ceiling, in a market growing at 6.5% CAGR with Asia-Pacific as the largest and fastest-growing region. Specify the unfilled grade first, step to 2200/2300 only when loads demand it, and make the documentation package — datasheets, certifications, batch traceability — the first gate in supplier qualification rather than an afterthought.
Figures in this guide are compiled from the cited source for procurement reference. Market sizes, growth rates and specification ranges reflect the source's research scenarios and vary by region, grade and manufacturer; verify current datasheets, test conditions and certifications directly with material suppliers. This article does not constitute engineering, legal or investment advice.
Related product categories
The materials and part types discussed above are grouped in our sourcing directory:
