Based on the information provided, silicone rubber shrinks when heated.
Understanding Silicone Rubber's Behavior with Heat
While many materials expand when heated, polymers like silicone rubber can exhibit a different behavior. The provided reference states that polymers like silicone rubber shrink on heating as their molecular chains curl up. This curling of the long polymer chains leads to a reduction in overall volume.
The reference also mentions that silicone is an elastomer with a large thermal expansion coefficient. Typically, a large thermal expansion coefficient implies significant expansion with increasing temperature. However, in the context of polymers like silicone rubber, the dominant effect upon heating, as noted in the reference, is the shrinkage due to molecular chain dynamics.
Practical Implications: Designing with Silicone Rubber
Because silicone rubber shrinks when heated, especially during processing like curing, this characteristic is crucial for manufacturing.
- Molding Design: When making and designing molds for silicone rubber products, the shrinkage rate should be carefully considered. This means molds must be designed slightly larger than the desired final product size to compensate for the shrinkage that occurs during curing and subsequent cooling or heating cycles.
This unique thermal behavior means that while silicone has a thermal expansion coefficient (indicating sensitivity to temperature changes), the overall effect of heating, particularly in processing contexts, is described as shrinkage.
