Silicone System MasterSil 153 Bonds Silicone Elastomer Compounds

MasterSil 153 is a two component, paste silicone compound for high-performance bonding and sealing. It is an addition cured system and does not require exposure to air for complete cross-linking. This silicone system, developed by Master Bond, features a convenient one-to-one mix ratio by weight, and will not outgas while curing. It has remarkable flexibility and high-temperature resistance while maintaining very low exotherm over an exceptionally long working life. MasterSil 153 bonds well to a wide variety of substrates including cured silicone rubber and withstands severe thermal cycling, vibration and shock. It is serviceable over the wide temperature range of -65°F to +400°F.

Bonding Silicone Elastomers

Silicone elastomers are difficult to bond, both to each other and to other substrates. The most effective adhesives for bonding silicones are other silicones, mainly one part RTVs and specially formulated pressure sensitive silicone compounds. However, bonding silicone elastomers with the use of other polymer compounds is possible as well.

In most cases, the highest bond strength will be attained with a proper and thorough pretreatment. There are two common pretreatment options available when bonding silicone elastomers. They include:

• Mechanical abrasion and solvent cleaning followed by the use of a primer. Common solvents used for cleaning include acetone and other ketones, alcohols and aromatics such as toluene and xylene. Soap and water washing has also been found to be helpful for enhancing adhesion of certain silicone rubber compounds.
• Gas plasma etching treats the surface with positive ion charges that enable the bonding of a silicone with a non-silicone type adhesive such as an epoxy by temporarily changing the nature of the surfaces. Bond strengths can be very high using plasma treatment and epoxy adhesives.

Master Bond offers a wide range of highly effective silicone elastomer bonding compounds. These systems offer outstanding bond strength and durability. Additionally, there are a number of specialty formulations for bonding silicone substrates. Most notable is MasterSil 711, a super-fast, one part, room temperature curing, vulcanizing silicone elastomer compound which provides remarkably fast cures with set up times occurring in as little as 3-5 minutes at ambient temperatures depending on humidity. MasterSil 713 is a unique, low viscosity, one-part silicone adhesive/sealant especially well suited for effective sealing and bonding of small gaps. MasterSil 800 and 801 provide unsurpassed thermal stability at temperatures as high as +600°F. They are black in color. A special translucent formulation called MasterSil 803 is available for +500°F service. MasterSil 705TC is a thermally conductive, electrically insulative compound for prolonged usage up to +400°F. It can withstand severe service temperature cycling and has proven ideal for heat sink attachment and other applications where superior heat transfer is required.

This information has been sourced, reviewed and adapted from materials provided by Master Bond Inc.

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