Two part toughened epoxy for bonding, sealing and encapsulation features good thermal conductivity

Key Features

  • Free flowing viscosity
  • High temperature resistance
  • Exceptionally long open time
  • Passes NASA low outgassing

Product Description

Master Bond Supreme 121AO is a thermally conductive epoxy for bonding, sealing and encapsulation. The mix ratio is 100:80 by weight. This system has a very long open time of 5-7 days and after mixing, it flows readily. Supreme 121AO requires oven curing. A typical cure schedule would be 1-2 hours at 200-210°F followed by 3-4 hours at 250°F and then 4-6 hours at 300°F. Additional post curing at 350°F for 2-4 hours will further enhance product properties. Supreme 121AO combines a high glass transition temperature along with an element of toughness, making it less rigid than typical higher temperature resistant epoxies.

Supreme 121AO bonds to a wide variety of substrates including metals, composites, glass, and many rubbers and plastics. It adheres especially well to glass, fibers and ceramics.

Supreme 121AO can withstand thermal cycling and mechanical stresses. Its physical strength profile is strong and steadfast, particularly its tensile modulus. It is a reliable thermal conductor while retaining excellent insulation properties. It has good resistance to chemicals including water, oils, fuels, acids and bases. The color of Part A is black and Part B is dark brown. Its service temperature range is -80°F to +550°F. It should be noted that Supreme 121AO is particularly well suited for potting and encapsulation applications. This product should be considered in demanding aerospace, electronic, optoelectronic and specialty OEM type applications where this product profile is needed.

Product Advantages

  • Good flow combined with long working life
  • Thermally conductive, electrically insulative
  • Superior physical strength properties
  • High glass transition temperature
  • Has an element of toughness
  • Combines exceptionally low shrinkage and high dimensional stability

Industrial Certifications

ASTM E595 Compliant

Meets EU Directive 2015/863





Supreme 121AO is available is various sizes and units to accommodate customer's needs.

Visual Media

Ideal for potting and encapsulation applications, Master Bond Supreme 121AO is a heat curing epoxy featuring excellent thermal conductivity and high temperature resistance. Scroll through this infographic to learn more.

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