Optically Clear, High-Flexibility Silicone Meets NASA Low-Outgassing Specifications

Master Bond MasterSil 981-LO is a two-component, addition-cure silicone system designed for bonding, sealing, coating, and encapsulating applications. It meets NASA low-outgassing specifications and features optical clarity, particularly in thin sections, making it well suited for aerospace, satellite, optical, and optoelectronic applications. The compound is 100% reactive, contains no solvents or diluents, and exhibits minimal shrinkage upon cure.

MasterSil 981-LO features a Shore A hardness of 20–30, a low modulus, and good flexibility, with an elongation of 200%–300% at 75°F. It withstands thermal shock and cycling without cracking or imparting stress on bonded components. The system is serviceable over a temperature range of -65°F to +400°F (-54°C to +204°C) and provides electrical insulation properties, including a dielectric strength of 450 volts/mil (1/8in thick specimen) and a volume resistivity greater than 10¹⁴ ohm-cm at 75°F. The refractive index measures 1.437.

This system features a forgiving 1:1 mix ratio by weight and a flowable, mixed viscosity of 12,500–17,500 cps at room temperature. Its three to four-hour working life for a 100-gram batch allows sufficient time for application and processing. The recommended optimal cure schedule is overnight at room temperature, followed by two to four hours at 135°F to 165°F. MasterSil 981-LO bonds to a variety of substrates, including metals, glass, plastics, ceramics, and many silicone rubbers. It is available in standard packaging ranging from 30 cc syringe kits to gallon kits, and is compatible with gun dispensers for automated applications.

Master Bond Low Outgassing Adhesives

Master Bond offers an extensive portfolio of low outgassing adhesive systems formulated for applications where vacuum compatibility and reliability are essential. These chemistries include epoxies, silicones, UV curables, and speciality compounds designed for use in aerospace, satellite, optical, and electronic environments.

Select grades meeting NASA low-outgassing specifications provide performance properties such as strong adhesion, electrical insulation, thermal stability, optical clarity, flexibility, and resistance to thermal shock. To learn more about low outgassing systems, visit https://www.masterbond.com/properties/low-outgassing-adhesives or contact technical support to discuss your application.

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Tel: +1-201-343-8983

For a full product description, please visit: https://www.masterbond.com/tds/mastersil-981-lo