Service temperature range comparison for elastomers: which rubber typically offers the widest continuous service window, roughly from −75°C up to about 275°C?
-
AButyl rubber
-
BSilicon rubber (misspelled)
-
CNitrile rubber
-
DSilicone rubber
Answer
Correct Answer: Silicone rubber
Explanation
Introduction / Context:Elastomer selection often hinges on temperature capability. Applications from cryogenic seals to high-temperature gaskets demand rubbers that retain elasticity across extreme ranges. Silicone rubber stands out for its broad usable window and resistance to heat and ozone.
Given Data / Assumptions:
- Target range: about −75°C to 275°C.
- Silicone rubbers maintain flexibility at very low temperatures and resist embrittlement at high temperatures.
- Butyl and nitrile have narrower ranges and poorer high-heat performance compared with silicone.
Concept / Approach:The siloxane backbone in silicone rubber provides high bond energy and low glass transition temperature, enabling elasticity at sub-zero conditions and resilience at elevated temperatures. Conventional hydrocarbon rubbers soften/degrade earlier, limiting their upper service temperature.
Step-by-Step Solution:Match the exceptional range to silicone performance.Eliminate butyl and nitrile due to narrower service windows.Select silicone rubber as correct.
Verification / Alternative check:Datasheets commonly list silicone continuous service up to ~200–250°C with peaks higher; specialized grades can approach 275°C; low-temperature flexibility extends below −60°C.
Why Other Options Are Wrong:Butyl and nitrile: limited by higher glass transition and poorer heat resistance.
Common Pitfalls:Confusing “silicon” (element) with “silicone” (polymer); spelling matters in specifications.
Final Answer:Silicone rubber