Dow 255 Primerless Elastomer

Dow 255 Primerless Elastomer Datasheet
  • Description for Dow 255 Primerless Elastomer

    Two part; 10:1 mix; non-corrosive; good dielectric properties; flexible elastomer; non-heat curable; tin catalyst cannot be inhibited; reversion possible with heat and pressure in sealed environments.

    Note: This material has been discontinued. Please view the Manufacturer's Recommended Replacement tab or call us at (262) 293-7970 for additional help.

    *See Terms of Use Below

    Application Type Pot, Encapsulate
    1 Part or 2 Part 2 Part
    Material Form Liquid, Silicone elastomer
    Industry Amplifiers, Connectors, Electronics, High voltage resistor packs, Sensors, Transformers, Relays
    Manufacturer Dow
    Chemistry Silicone, Silicone elastomer
    Cure Method Base/Curing agent
    Cure Temperature (°C) 20 to 25, 20 to 25
    Cure Time (min) Rapid, ~14400 (Seconds), 1,440
    Viscosity (cPs) 5,500, Flowable
    Color Black, Gray
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
  • Technical Data for Dow 255 Primerless Elastomer

    Overview
    • Application Type
    • 1 Part or 2 Part
      • 1 Part or 2 Part - 2 Part
      • Part A Name - Base
      • Part B Name - Curing Agent
    • Material Form
      • Elastomer - Silicone elastomer
      • Liquid
    • Industry
    • Chemistry
    • Application Method
      • Dispenser - Automated mixing, Dispensing equipment, Manual mixing
    • Cure Method
      • 2-Part Cure - Base/Curing agent
    • Color
      • Black
      • Gray
    Specifications
    Cure Specs
    Cure Temperature (°C) 20 to 25, 20 to 25 Test Method
    Cure Time (min) Rapid, ~14400 (Seconds), 1,440 Test Method
    Viscosity (cPs) 5,500, Flowable
    Work / Pot Time (min) <5.00 Test Method
    Mix Ratio 10:1 (by volume), 10:1 (by weight)
    Bond Strength
    Shear Strength (psi) 44 Test Method
    Material Resistance
    Ozone Resistance Ozone resistance
    Chemical Resistance Good
    UV Resistance UV resistance
    Environmental Resistance Environmental resistance
    High Temperature Resistance (°C) 200
    Low Temperature Resistance (°C) -45, -55
    Moisture/Humidity Resistance Moisture/humidity resistance
    Conductivity
    Dissipation Factor 0.01700, <0.00590 Test Method
    Dielectric Strength (V/mil) Good, 22,204,724, Durable
    Dielectric Constant 2.95, 2.83 Test Method
    Thermal Conductivity (W/m°K) 0.26, 2.61500039538806e-3
    Volume Resistivity (O) 1.1e15 (ohms/cm)
    Hardness
    Shore A Hardness 25
    Flexibility Flexible
    Other Properties
    Specific Gravity 1.300
    Coefficient of Thermal Expansion (CTE) 311 (Linear (micron/m °C or ppm ))
    Flash Point (°F) 122.0
    Business Information
    Shelf Life Details Dow Corning 255 Elastomer should be kept refrigerated (10°C/50°F) until use. Any special storage and handling instructions will be printed on the product containers.
  • Best Practices for Dow 255 Primerless Elastomer

    *See Terms of Use Below

    1. Surface Preparation

      In applications requiring adhesion, priming will be required for the silicone encapsulants. See the Primer Selection Guide for the correct primer to use with a given product. For best results, the primer should be applied in a very thin, uniform coating and then wiped off after application. After application, it should be thoroughly air dried prior to application of the silicone elastomer. Additional instructions for primer usage can be found in the Dow Corning literature, “How To Use Dow Corning Primers and Adhesion Promoters” (Form No. 10-366) and in the information sheets specific to the individual primers.

    2. Mixing

      Dow Corning silicone 10:1 encapsulants are supplied in two parts as lot-matched base and curing agent that are mixed in a ratio of 10 parts base to one part curing agent, by weight. After thoroughly mixing base and curing agent, agitate gently to reduce the amount of air introduced. Allowing the mixture to set for 30 minutes before pouring may be adequate for removal of the air introduced during mixing.

    3. Deairing/Degassing

      If air bubbles are still present, vacuum deairing may be required. Deair in a container with at least four times the liquid volume to allow for expansion of material. Air entrapped in the mixture can be removed by using a vacuum of 28 to 30 inches Hg. Continue the vacuum until the liquid expands and settles to its original volume and bubbling subsides. This may take 15 minutes to 2 hours depending on the amount of air introduced during stirring. For best curing results, glassware and glass or metal stirring implements should be used. Mix with a smooth action that does not introduce excess air.

    4. Testing

      If a substrate or material is questionable with respect to potentially causing inhibition of cure, it is recommended that a small scale compatibility test be run to ascertain suitability in a given application. The presence of liquid or uncured product at the interface between the questionable substrate and the cured gel indicates incompatibility and inhibition of cure.

  • Manufacturer's Recommended Replacement Materials

    *See Terms of Use Below

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Cure Temperature Test Methods
Cure Temperature Cure Time Test Method
20 to 25°C
20 to 25°C These data were collected on 50-100 gram samples of a lot believed to be typical and should be used as initial estimates of cure times. Times will vary slightly from batch to batch and can be longer or shorter due to thermal mass of your parts and your heating ramp rate. Pretesting is recommended to confirm adequate cure for your application.
Cure Time Test Methods
Cure Time Test Method
Rapid
~14400 (Seconds) These data were collected on 50-100 gram samples of a lot believed to be typical and should be used as initial estimates of cure times. Times will vary slightly from batch to batch and can be longer or shorter due to thermal mass of your parts and your heating ramp rate. Pretesting is recommended to confirm adequate cure for your application.
1,440 min For primerless adhesion products, cure time is based on time to reach durometer. Full adhesion may take more time at cure temeprature.
Work / Pot Time Test Methods
Work / Pot Time Temperature
<5.00 min Room temperature
Shear Strength Test Methods
Shear Strength Type
44 psi Lap shear strength
Dielectric Constant Test Methods
Dielectric Constant Test Method
2.95 (100 Hz)
2.83 (100 kHz)
Dissipation Factor Test Methods
Dissipation Factor Test Method
0.01700 (100 Hz)
<0.00590 (100 kHz)