At the high-temperature end, the durability of the cured silicone elastomer is time and temperature dependent. Factors that may influence performance are configuration and stress sensitivity of components, cooling rates and hold times, and prior temperature history. For low temperature performance, thermal cycling to conditions such as -55☌ (-67☏) may be possible, but performance should be verified for your parts or assemblies. However, at both the low and high temperature ends of the spectrum, behavior of the materials and performance in particular applications can become more complex and require additional considerations and should be adequately tested for the particular end-use environment. USEFUL TEMPERATURE RANGES - For most uses, silicone elastomers should be operational over a temperature range of -45 to 200☌ (-49 to 392☏) for long periods of time. Pot life is defined as the time required for viscosity to double after base and curing agent are mixed and is highly temperature and application dependent. Initially, cure is evidenced by a gradual increase in viscosity, followed by gelation and conversion to a solid elastomer. POT LIFE AND CURE RATE - Cure reaction begins with the mixing process.
Ideal cure conditions for each product are given in the product selection table. Room temperature cure encapsulants may also be heat accelerated for faster cure.
Dow silicone encapsulants may be either room temperature (25 ☌ /77☏) or heat cured. If this technique cannot be used, the unit should be evacuated after the silicone encapsulant has been poured/ dispensed. When practical, pouring/dispensing should be done under vacuum, particularly if the component being potted or encapsulated has many small voids. Care should be taken to minimize air entrapment. PROCESSING/CURING - Thoroughly mixed the silicone encapsulant may be poured/dispensed directly into the container in which it is to be cured. Additional instructions for primer usage can be found in the information sheets specific to the individual primers. After application, it should be thoroughly cured prior to application of the silicone elastomer. For best results, the primer should be applied in a very thin, uniform coating and then wiped off after application. PREPARING SURFACES - In applications requiring adhesion, priming will be required for many of the silicone encapsulants.
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