Plastic Deformation Caught In Action

Soft polymers, such as those in wire insulation, can deform under high voltages
Soft polymers, such as those in wire insulation, can deform under high voltages

Want new and improved plastics and polymers for all kinds of consumer and industrial products? Well, you first need to understand the weaknesses of current plastics and polymers and what causes them. To understand why soft polymers, like the kind that go into wire insulation, lose their integrity when exposed to high electrical currents, a research group at Duke University has observed for the first time what actually happens on the microscopic scale.

Scientists have known for ages that plastics break down, but they hadn’t been able to see the process occurring. In a paper published in the American Physical Society‘s Physical Review Letters, materials scientist Xuanhe Zhao and his team described a set of experiments where they watched in real time how plastic deformed to ultimately break down as the electric voltage increased.

Zhao’s team did the experiments by attaching the soft polymer to another rigid polymer layer which acted as a support for the soft polymer as it came apart. They saw that the polymers first formed creases and then craters which lead to eventual breakdown of the polymer’s structural integrity.

As explained in a press release written by senior science writer Richard Merritt at Duke’s Pratt School of Engineering Communications Office,

The findings by the Duke engineers could help in developing new materials to improve the durability and efficiency of any polymer that must come into contact with electrical currents, as well as in the emerging field of energy harvesting.

You too can watch the soft polymer break down in the embedded YouTube video below, posted by graduate student Qiming Wang, who worked on the project. You can also see a discussion of the work on a blog that Wang maintains on iMechanica.

Source: “Creasing to Cratering: Voltage Breaks Down Plastics,” 03/07/11
Source: “Creasing to cratering instability in polymers under ultrahigh electric fields,” Physical Review Letters, 03/14/11
Image by Andres Rueda, used under its Creative Commons license.

Rajendrani "Raj" Mukhopadhyay is a science writer and editor who contributes news stories and feature articles on scientific advances to a variety of magazines. Raj holds Ph.D. in biophysics from Johns Hopkins University.