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Thermosil 4000 is a thixotropic, two-part (A/B), silicone sealant that is applied as a potting compound for low-pressure compressor stator vanes in jet aircraft engines. Its superior elastic properties also allow it to function as a damping compound to minimize vane vibration and stress. Thermosil 4000 meets the requirements of Pratt & Whitney specification PWA 404-2. It can withstand operating temperatures up to 350˚F (177˚C). Thermosil 4000 is available in pre-measured void-free A/B component injection cartridges.

Product Type: 2K (2 component) Sealant

Application Area: Aerospace Engines

Chemical Family: Silicones

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Identification & Functionality

Chemical Family

Features & Benefits

Applications & Uses

Application Area
Important Application Information

Component Matching: Thermosil 4000 is supplied as a two-part (A/B), precision metered, component injection cartridge kit. The product should be mixed using the specific Part A and Part B components supplied with the kit. Using a different Part A or Part B component may affect product properties.

Curing Inhibition: Thermosil 4000 is a platinum-catalyzed addition reaction silicone rubber. The curing mechanism is sensitive to inhibition by amines, sulfur, or tincatalyzed rubbers.

Mixing, Containers, and Tools: Thermosil 4000 cartridges are designed to be mixed by automated mixing equipment specific to that purpose.

The following materials/tools are approved for mixing and handling:

  • Stainless steel, glass, or high-density polyethylene (HDPE) containers
  • Stainless steel or HDPE hand tools
  • Stainless steel mixing equipment

All tools and equipment must be thoroughly cleaned after use. Clean with mineral spirits, followed by a solvent rinse.

Mixing and Application Instructions

Automated Mixing: Thread the Part B dasher rod into the Part A cartridge. Use a ramrod to inject Part B into the middle of the cartridge containing Part A. Install the cartridge on an automatic mixer and set the mixer’s stroke length so that the open spoke mixer will contact the plunger without displacing it. Mix for 2 1/2 minutes. When mixing is complete, unthread the dasher rod and install the cartridge in a pneumatic or mechanical dispensing gun.

Tooling: Tool Thermosil 4000 with acetone, methyl ethyl ketone (MEK), or isopropyl alcohol (IPA).

Properties

Cured Properties
ValueUnitsTest Method / Conditions
Specific Gravity1.25
Tensile Strength850.0Psi
Elongation350.0%
Lap Shear Strength700.0Psi
Cohesive Failure100.0%
Hardness65.0Shore A
Hardness (16 hours at room temperature)45.0Shore A
Uncured Properties
ValueUnitsTest Method / Conditions
Consistency (Part A)Thixotropic
Mix Ratio (Part A, by weight)10.0
Mix Ratio (Part B, by weight)1.0
Flow (After 15 minutes)0.05in.
Working Life1.5Hours
Extrusion Rate230.0g/min

Packaging & Availability

Packaging Type

Storage & Handling

Storage, Shelf Life, and Recertification

Thermosil 4000 has a shelf-life of six (6) months from the date of shipment when stored in its original, unopened containers at temperatures not exceeding 90˚F (32˚C). FMi Chemical offers free recertification of its products where permitted.