CB6957 Polybenzimidazole Sheet (PBI Sheet)

Polybenzimidazole Sheet (PBI Sheet) Description

Polybenzimidazole (PBI) Sheet is a thermoset material produced from PBI powder. It has a glass transition temperature of 435°C, which permits continuous operation at 400°C and short-term exposure to 500°C. The sheet exhibits a flame resistance with an oxygen index of 58%, and its mechanical properties include a tensile strength of 130 MPa, an elastic modulus of 5.5 GPa, Shore D hardness of 97 and 20% elongation. The coefficient of thermal expansion is 23 x10-6/K from 0–400°C, thereby ensuring dimensional stability during thermal cycling. Its electrical properties are defined by a volume resistivity exceeding 2 x10^15 ohm-cm and a dielectric strength of 23 kV/mm at 300°C, with a stable dielectric constant of 3.3–3.4 and a dissipation factor under 0.003 across frequencies from 1 kHz to 0.1 MHz. The sheet is chemically resistant to concentrated sulphuric and nitric acids, 50% sodium/potassium hydroxides, ketones, fuels, steam and high-pressure water. In addition, the material exhibits gamma/X-ray radiation resistance and a total mass loss (outgassing) of less than 0.1% in a vacuum environment. Its limitations include a dark amber colouration, a cost approximately 5–10 times that of PTFE and non-melt processability. These characteristics justify its use in rocket thermal shields, semiconductor wafer handling fixtures, fuel cell components and firefighting equipment, where operating conditions exceed those of conventional materials.

Polybenzimidazole Sheet (PBI Sheet) Applications

PBI Sheet is employed in aerospace thermal protection systems, including rocket nozzle liners and re-entry vehicle heat shields that function at temperatures above 400°C under extreme aerodynamic stress. In semiconductor manufacturing, it is used for plasma-resistant wafer handling fixtures and vacuum chamber insulators, given that the outgassing is below 0.1% TML and the material is radiation stable. In the energy sector, the sheet is applied to fuel cell bipolar plates and electrolyser gaskets, utilising its proton conductivity in high-temperature, corrosive environments. Industrial applications include chemical valve seals, non-lubricated bearings and pump components that face concentrated acids (e.g. 98% H₂SO₄) or steam. Firefighting and defence equipment utilise the material in face shields, aircraft firewall barriers and flame-resistant gloves (oxygen index 58%). Furthermore, it is used for high-voltage electrical insulation in transformers and for seals in hydrogen infrastructure, where the dielectric strength of 23 kV/mm and hydrogen impermeability are essential. The material may replace metals or ceramics in corrosive environments exceeding 400°C despite its higher cost.

Polybenzimidazole Sheet (PBI Sheet) Packaging

Our products are packaged in customised cartons of various sizes according to the material dimensions. Small items are securely packed in PP boxes while larger items are placed in custom wooden crates. We adhere strictly to packaging customisation and utilise appropriate cushioning materials, thereby ensuring effective protection during transportation.

Packaging: Carton, Wooden Box, or Customized.

Kindly review the packaging details provided for your reference.

Manufacturing Process

1.       Testing Method

(1)    Chemical composition analysis is performed using techniques such as GDMS or XRF to verify compliance with purity requirements.

(2)    Mechanical properties testing is carried out, including tensile, yield and elongation tests to assess material performance.

(3)    Dimensional inspection measures thickness, width and length to ensure that specified tolerances are met.

(4)    Surface quality inspection identifies defects, such as scratches, cracks or inclusions, through visual and ultrasonic examination.

(5)    Hardness testing confirms material hardness to ensure consistency in mechanical performance.

Please refer to the testing procedures of Stanford Advanced Materials (SAM) for detailed information.

Polybenzimidazole Sheet (PBI Sheet) FAQs

Q1. What defines PBI Sheet's core capabilities?

The sheet has a glass transition temperature of 435°C, allowing continuous operation at 400°C and brief exposure to 500°C. It has an oxygen index of 58% and is resistant to concentrated sulphuric and nitric acids, 50% sodium hydroxide, solvents and steam. Mechanical performance is indicated by a tensile strength of 130 MPa, while electrical insulation is maintained with a volume resistivity exceeding 2 x10^15 ohm-cm at 300°C.

Q2. Where is it critically used?

This material is used in aerospace thermal shields for rocket nozzles, semiconductor plasma-etch components, fuel cell bipolar plates, firefighter face shields and chemical valve seals. It is also employed in scenarios where metals or ceramics must be replaced in environments exceeding 400°C, such as in deep-well drilling tools or hydrogen infrastructure seals.

Q3. How does it compare to PEEK or PTFE?

PBI Sheet operates at temperatures approximately 200°C higher than PEEK and exhibits an oxygen index of 58% compared with 35% for PEEK. In contrast to PTFE, it withstands alkalis and offers a tensile strength of 130 MPa together with electrical insulation (volume resistivity of 2 x10^15 ohm-cm at 300°C).

Related Information

1.       Common Preparation Methods

Polybenzimidazole (PBI) Sheet is manufactured through high-temperature compression moulding of purified PBI powder. The process begins with pre-drying the powder at 150–200°C under vacuum to reduce moisture to below 0.1%. The powder is then loaded into precision-machined steel moulds coated with a release agent such as boron nitride. A controlled thermal-pressure cycle is applied, whereby the mould is heated to between 380–450°C at a rate of 5–10°C per minute under an inert gas (N₂ or Ar). Stepwise compression up to 20–40 MPa is then applied to eliminate voids and to ensure a uniform densification. The temperature is maintained for 2–5 hours to achieve a density near 1.3 g/cm³, after which the mould is cooled slowly at 1–2°C per minute to below 200°C under pressure. The demoulded sheet undergoes post-curing at 250–300°C for 6–24 hours to promote cross-linking and to reduce residual stresses. Final processing includes precision machining (CNC milling or lathing) to meet dimensional tolerances and surface finishing by sanding or polishing to achieve required roughness. This method yields sheets with thicknesses ranging from 0.5 mm to 50 mm and a characteristic dark amber colour, with isotropic properties. Alternative techniques, such as isostatic pressing or solution casting, exist; however, they are seldom used for thicker sheets due to challenges associated with solvent removal. The absence of melt processability necessitates this solid-state moulding approach.