Polyimide (PI) Sheet/Rod

Updated: 2026-09-11

Overview

Polyimide (PI) Sheet/Rod is a premium engineering plastic renowned for its ability to withstand extreme temperatures and harsh chemical environments. Developed in the 1960s, PI materials combine the flexibility of polymers with performance metrics rivaling metals. Sheets and rods are manufactured through high-pressure sintering or machining from PI blocks. These forms are indispensable in industries where traditional plastics or metals fail, such as aerospace (seals, bushings), electronics (insulators, flex circuits), and automotive (thermal barriers). Their inherent flame retardancy and minimal outgassing make them ideal for vacuum applications.

Structure and Working Principle

Polyimide's molecular structure features rigid aromatic rings and imide linkages, granting exceptional thermal and oxidative stability. Sheets and rods retain dimensional integrity across a wide temperature range (-269°C to +400°C), with negligible creep under load. In electrical applications, PI's dielectric strength (up to 300 kV/mm) and surface resistivity prevent current leakage. As bearings or bushings, its low friction coefficient (0.1–0.3) and self-lubricating properties reduce wear without external lubricants.

Key Features

Thermal Performance: PI maintains tensile strength above 100 MPa at 250°C, outperforming PTFE and PEEK. Continuous service at 300°C is achievable with some grades. Chemical Resistance: Resistant to most solvents, oils, and acids, though prolonged alkali exposure degrades performance. Autoclavable and radiation-stable. Machinability: PI rods/sheets can be CNC-machined to tight tolerances (±0.05 mm), but require sharp tools to avoid melting or delamination.

Application Areas

Electronics: Flexible PCBs, coil bobbins, and chip carriers leverage PI's dielectric properties. Thin films (e.g., Kapton®) are used in smartphones and EVs. Industrial: Seals and thrust washers in chemical pumps, non-stick surfaces for plastic extrusion molds. FDA-compliant grades suit food processing. Aerospace: Thermal blankets, rocket engine components, and cryogenic insulation benefit from PI's light weight and thermal stability.

Maintenance and Precautions

PI components require minimal maintenance due to their wear resistance. Avoid alkaline cleaners; isopropyl alcohol is recommended for surface cleaning. Storage: Keep in dry conditions below 40°C to prevent moisture absorption (up to 3% by weight). UV degradation can occur outdoors—use carbon-black-filled grades for sunlight exposure. Safety: Machining produces respirable dust; use local exhaust ventilation and NIOSH-approved masks. Coolants reduce thermal stress during high-speed cutting.

B2B Procurement Guide

Suppliers: Major producers include DuPont (Vespel®), Mitsui Chemicals (Aurum®), and SABIC (EXTEM™). Regional distributors often stock standard sizes. Customization: Sheets/rods are available in thicknesses from 0.05 mm to 100 mm. Colors range from amber to black (with additives). Lead times for custom sizes vary from 2–8 weeks. Cost Factors: Prices scale with purity (e.g., >99.9% for semiconductor use) and additive packages (graphite, MoS2). Bulk orders (100+ kg) typically secure 10–15% discounts.