Finding Why Insulators Fail
When most people envision an electrical wire, they likely picture a piece of copper jacketed by some plastic insulator. That insulator is extremely important as it protects the inner wire from being damaged by the environment or shorting out. Over time though, the polymer insulator will fail, and now researchers at Duke University are on their way to finding out why.
Within polymers there are tiny bubbles of liquid or air that are present as defects from the manufacturing process. It has been known for some time that these bubbles, when exposed to an electric field, will deform, and in a strong enough field, they cause the insulator itself to fail. The mechanism behind this deformation is not well understood, in large part to the bubbles being in a solid which also fails at the almost the exact moment that needs to be studied. The researchers found a way to make their observations quickly enough and have found something new. It has previously been shown that the bubbles end up with a cylindrical shape when the polymer fails, but before they take on that shape, they first form a sharp tip. This suggests a new mechanism is at work than what was previously believed to be the case.
This discovery has numerous impacts including in the energy industry, where polymers would like to be used for improved capacitors, but the lack of understanding concerning how they fail has been hindering their adoption. However, as this research also shows how the polymer itself is deformed due to strong electric fields, the researchers are going to see about making a lens that can have its shape changed by an electric field for use in ophthalmology.