Featured Research

from universities, journals, and other organizations

Materials break, then remake, bonds to build strength: Bending synthetic material makes it stronger, not weaker

Date:
August 4, 2013
Source:
Duke University
Summary:
Microscopic tears in a new kind of human-made material may actually help the substance bulk up like a bodybuilder at the gym.

Microscopic tears in a new kind of human-made material may actually help the substance bulk up like a bodybuilder at the gym.

"We've shown how normally destructive mechanical forces can be channeled to bring about stronger materials," said Duke chemist Steve Craig, who led the research. "The material responses are like Silly Putty transforming into a solid as stiff as the cap of a pen or a runny liquid transforming into soft Jell-O."

Scientists could one day use the stress-induced strength from these new materials to make better fluids such as engine oil, or soft-structure substances such as artificial heart valves. Materials like this wear out over time because of the repeated mechanical forces they experience during use. But Craig said if a material had properties to slow down its destruction, it would greatly improve quality of life.

It is the first time scientists have used force-induced chemistry within a material to make it stronger in response to stress. The results appear Monday, Aug. 5, 2013, in Nature Chemistry.

In past experiments, Craig's team has gripped and tugged on individual molecules of a material to see how it reacted at the atomic level. Now, the scientists have scaled up the material to contort it macroscopically and see how it responds.

Craig said the response is similar to what happens when a person lifts weights. Those individual stresses trigger biological processes in the muscles that ultimately increase the person's strength.

"It's the same idea chemists would like to use for synthetic materials," he said. "Everyday materials can wear out with repeated stress. Think of your favorite t-shirt or even the oil in your car engine. Wear after wear, fire after fire, these materials break down."

The new human-made materials Craig's team is making have characteristics already in place so that when a stress triggers a bond to break, it breaks in a way that triggers a subsequent reaction forcing the busted atomic bonds to reform new ones.

"It's like snapping a string. But before the string snaps, sites along it form so that when it breaks it can become tied to another string," Craig said.

The scientists first stressed one of the test materials by pulsing high-intensity sound waves through them. The sound waves create bubbles, which typically collapse and break the bonds of the molecules in the material. The forces breaking atoms in the new materials, however, triggered the formation of new bonds, which strengthened the liquid by transforming it into a soft Jell-O consistency.

To test the strength-building ability of a Silly-Putty-like material, the team used a twin-screw extruder, which is as damaging as it sounds. The machine bores two screws into a material and pulls the material through it, destroying some of the material's molecular bonds. Here too, the synthetic material formed more new bonds than those destroyed, becoming much more solid in structure and stronger.

Craig said one drawback to the new materials is that forces deform the material's initial structure. It is stronger at the end, but is not the same shape. The team now plans to create synthetic materials that can repair themselves after stress and retain their original shape, he said.

The team would also like to engineer the material to respond faster. "At this point it takes minutes for the strengthening reactions to start changing the material," Craig said. "We could see it happening as quickly as milliseconds."


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Ashley L. Black Ramirez, Zachary S. Kean, Joshua A. Orlicki, Mangesh Champhekar, Sarah M. Elsakr, Wendy E. Krause, Stephen L. Craig. Mechanochemical strengthening of a synthetic polymer in response to typically destructive shear forces. Nature Chemistry, 2013; DOI: 10.1038/nchem.1720

Cite This Page:

Duke University. "Materials break, then remake, bonds to build strength: Bending synthetic material makes it stronger, not weaker." ScienceDaily. ScienceDaily, 4 August 2013. <www.sciencedaily.com/releases/2013/08/130804144454.htm>.
Duke University. (2013, August 4). Materials break, then remake, bonds to build strength: Bending synthetic material makes it stronger, not weaker. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2013/08/130804144454.htm
Duke University. "Materials break, then remake, bonds to build strength: Bending synthetic material makes it stronger, not weaker." ScienceDaily. www.sciencedaily.com/releases/2013/08/130804144454.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins