Operating
temperature range
The choice of the potting or adhesive materials are often determined by the required operating temperature range, which defines the temperature range in which certain properties (e.g. mechanical) should not change significantly. Property changes are reversible in certain ranges within the recommended operating temperature range.
Representative products
WEVOPUR 403
- Insulation class F
- Good chemical resistance
- Good behaviour under thermal shock
- Suitable for explosion-proof applications
WEVOPUR PD 445
- Operating temperature range: -60 °C to +120 °C
- Excellent flow properties
- High flexibility
- Surface tack
WEVOPOX 2501 FL / WEVODUR CC 5001
- Insulation class H (180 °C)
- UL 94 V-0
- Long pot life
- Cold curing
Differentiation in operating temperature range
Resins
Conventional polyurethane systems are suitable for applications up to insulation class B (130 °C), but polymer matrix degradation increases at higher temperatures. Hybrid PU systems are suitable for applications up to insulation class F (155 °C). When systems for insulation class H (180 °C) are required, thermosetting epoxy resin and silicone-based systems must be used. Thus, the required continuous temperature range is a critical parameter when choosing the resin system.
When selecting the system, it will also be necessary to distinguish between short-term high temperature stress and continuous temperature exposure. Most polymer systems tolerate short-term overheating, which is documented by temperature index charts.
When talking about the operating temperature range, it is also necessary to include thermal stability, which is understood to be the temperature above which degradation of the system occurs during sustained exposure.
Adhesives
Temperature stability is also relevant for adhesives. In this case it refers to the bonding strength achieved by an adhesive under specified parameters at a certain temperature.
One special case here is temperature resistance, which describes the stability of an adhesive at a sustained temperature, above which chemical decomposition begins.