Master Bond MasterSil 153AO is an addition-cured, two-part silicone with a self-priming property. The company reports that the adhesive has a high tensile lap shear strength, especially for a silicone. The system is thermally conductive and electrically insulating.

“The key feature of MasterSil 153AO is that it provides the ability to minimize stress, with no compromise on strength,” said Rohit Ramnath, senior product engineer. “Although it is not considered a structural adhesive, it provides a truly remarkable combination of flexibility and strength that other silicones do not provide.”

This silicone product has an elongation between 100-120% and a tensile lap shear strength of 700-800 psi. It provides a thermal conductivity of 0.93-1.08 W/(m•K), a volume resistivity of more than 1,014 ohm-cm, a coefficient of thermal expansion of 150-180 x 10-6 in/in/°C, and hardness of 65-75 Shore A. It is serviceable over the temperature range of -65°F to +400°F.

With an easy-to-use mix ratio of 1 to 1 by weight, MasterSil 153AO cures with the addition of moderate amounts of heat. For example, optimal cure schedule is overnight at room temperature followed by 2-4 hrs at 135°F-185°F. Upon mixing, it retains its smooth paste consistency and minimal flow. It has a working life of 4-6 hrs for a 100-g mass at 75°F.

According to Master Bond, this compound bonds well to a variety of substrates, including metals, glass, ceramics, many plastics, and silicone rubbers. It is available for use in kits, with sizes ranging from ½ pint, pint, quart, and gallons. White in color, MasterSil 153AO is generically low outgassing, contains no solvents, has a low linear shrinkage upon curing, and is RoHS compliant.

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