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Toward Sustainable Electronics

To reduce electronic waste, a diverse team of engineers searches for new materials, training a savvy workforce along the way

by Stephen K. Ritter
April 1, 2013 | A version of this story appeared in Volume 91, Issue 13

Credit: Lucy Wang Bruce
Purdue’s Bruce (left) and Howarter discuss samples of an epoxy resin/amine-modified clay composite for making halogen-free flame-resistant circuit boards.
Alexandra Bruce (left) and John Howarter at Purdue University discuss samples of an epoxy resin/amine-modified clay composite being studied as a model material to make halogen-free flame-resistant circuit boards. In the bottle on the table is an amine-modified clay dissolved in acetone.
Credit: Lucy Wang Bruce
Purdue’s Bruce (left) and Howarter discuss samples of an epoxy resin/amine-modified clay composite for making halogen-free flame-resistant circuit boards.

Laptops, smartphones, e-book readers, flat-screen TVs. Modern society is in love with its electronic gadgets. But one problem lingers: Most of these devices have short life spans and aren’t designed to be recycled.

When they reach the end of their useful lives, these electronics are often tucked away in a drawer or stashed in the basement. We might throw them away in the trash, or more conscientiously turn them over to a recycling center. But when it comes down to it, very little of our once-precious electronics is recycled. Most is typically burned or dumped, usually in clandestine operations in developing countries. In this process, heavy metals, dioxins, polyaromatic hydrocarbons, and other toxics enter the environment via smoke or residues that filter into streams and groundwater.

The electronics industry isn’t about to stop making its high-demand products because of their environmental burden. But the industry recognizes the cascade of challenges it faces, so manufacturers, retailers, and government and nongovernmental organizations are on the road to finding solutions. Together, these stakeholders have begun developing new products that use fewer toxic materials. And they are devising ways to make recycling easier. But there is still a long way to go.

That’s where an interdisciplinary team of engineers from Purdue University and Tuskegee University hopes to help. They have initiated a comprehensive international effort to develop new materials and technologies to replace conventional electronics with more sustainable ones. Along the way, they are training a workforce of scientists and engineers to ease the transition.

“We want to create materials that will allow electronic devices and their components to be disassembled, recycled, and reused,” says Carol A. Handwerker, a materials engineering professor at Purdue who is helping lead the program. “There is a growing realization that the traditional linear model of consumption—design it, build it, use it, throw it away—has long ceased being viable for electronics.”

The Purdue-Tuskegee Global Traineeship in Sustainable Electronics is being supported by a $3.2 million grant from the National Science Foundation’s Integrative Graduate Education & Research Traineeship (IGERT) program. The initiative currently includes eight Purdue students and three Tuskegee students representing materials science and engineering, management, and political science departments. They are the first group of a total of 28 students slated to receive the two-year IGERT electronics traineeships.

Credit: Courtesy of Vertonica Powell-Ross
Tuskegee’s Powell-Rose applies an epoxy resin to flax fiber mats before individual mats are stacked for compression molding. These biobased composite prototypes are being studied as alternatives to metal or plastic computer housings.
Vertonica Powell-Ross of Tuskegee University applies an epoxy resin to flax fiber mats before individual mats are stacked for compression molding. These biobased composite prototypes are being studied as alternatives to metal or plastic computer housings.
Credit: Courtesy of Vertonica Powell-Ross
Tuskegee’s Powell-Rose applies an epoxy resin to flax fiber mats before individual mats are stacked for compression molding. These biobased composite prototypes are being studied as alternatives to metal or plastic computer housings.

Handwerker and her colleagues are working closely with the International Electronics Manufacturing Initiative (iNEMI), a consortium of electronics manufacturers, suppliers, associations, government agencies, and universities that guides the design, manufacturing, and recycling of electronics.

“The Purdue-Tuskegee program is bringing in students from different disciplines and getting a strong interaction between industry, nongovernmental organizations, and universities on a global level,” says Robert C. Pfahl Jr., a mechanical engineer formerly with Motorola and now a vice president of iNEMI. “It comes at a time when the issues on developing sustainable electronics are getting more complex and the answers are becoming less clear.”

iNEMI began identifying areas for improving the sustainability of electronics as early as the mid-1990s, Pfahl says. Among the first targets was removing brominated flame retardants in plastics and lead in solder used to make electrical connections. Electronics makers have eliminated these materials from most handheld devices, Pfahl says. But that was the low-hanging fruit. The materials are still used in larger devices such as computers.

One challenge for those larger devices is working around the plastics additives that help meet mechanical and electrical specifications. “There really aren’t good solutions for some materials,” Pfahl says. “There are better solutions, but none of them are perfect.”

Industry is also moving forward on designing for recycling, he adds, but it too is a work in progress. Metal recycling is easier to address because copper, gold, and other metals are valuable. But the plastic parts in electronics often contain a variety of additives, requiring they be manually separated for recycling. It ends up being more cost-effective just to trash those parts.

So the industry is looking to improve life-cycle analysis of the different classes of devices it produces, Pfahl continues. “The real issue is having good, reliable data,” he says. Still, getting that data takes time. “Often by the time you complete an analysis, the material is no longer being used.”

The Purdue-Tuskegee program aims to speed up that process en route to developing sustainable electronics, Handwerker says. “It is specifically designed to train students how to think about developing a new technology in a specific way and to broadly put it into practice,” she says.

A by-the-numbers box showing how much electronic waste is produced and recycled.
Credit: Man with e-waste pile (Newscom), computer, computer pile (Shutterstock)

As such, the program includes courses on sustainability and manufacturing, “everything from the science of semiconductors to consumer behavior,” Handwerker says. In June, the students will be traveling to India for two weeks to get a firsthand look at electronics manufacturing. They will experience the entire product life cycle, from visiting a mine digging up raw materials all the way to witnessing e-waste recycling under the worst conditions. The program culminates with the students doing internships.

Handwerker moved to Purdue eight years ago to work on sustainable electronics. Previously she was head of the Metallurgy Division at the National Institute of Standards & Technology. At NIST, her team worked in collaboration with iNEMI to develop a tin-silver-copper alloy as a lead-free replacement for tin-lead solder used for making electrical connections in circuit boards and microchips. Her research now includes developing nanoparticle-based connections for next-generation circuits that perform better but use less material.

The industry is taking aim at finding replacements for several hazardous materials that currently go into building computers, TVs, and mobile devices. One is polyvinyl chloride, a chlorinated polymer used as flame-resistant electrical insulation in power cords and circuit board sockets. Another target is halogenated compounds used as flame retardants in epoxy resins used to make circuit boards. And the industry hopes to continue reducing toxic heavy metals such as lead, mercury, and cadmium. An overarching goal is to reduce greenhouse gas emissions related to product manufacturing and use.

But the engineers face an uphill battle. Any new materials they come up with have to meet the electrical, mechanical, and safety performance standards required of the currently used materials. And they can’t cost a penny more.

Researchers in the Purdue-Tuskegee program have those challenges in the front of their minds as they try to develop more sustainable materials, including biobased plastics, adhesives, and composites as well as halogen-free flame retardants.

The brominated flame retardants found in many such devices have come under intense scrutiny because of their toxicity, environmental persistence, and bioaccumulation, says Purdue IGERT Fellow Alexandra Bruce. Bruce, who grew up on a small livestock farm in rural Iowa and started college when she was 16, graduated last year with a materials engineering degree from Iowa State University. In collaboration with Purdue materials engineering professor John Howarter and Purdue civil engineering professor and IGERT coinvestigator Inez Hua, Bruce is now looking for a halogen-free replacement for the tetrabromobisphenol A-based epoxy resin commonly found in fire-resistant circuit boards.

In this material, the brominated flame retardant is built into the plastic rather than added to it. When the plastic burns, it forms denser-than-air HBr gas that suffocates a fire, Bruce explains.

Bruce is investigating montmorillonite clay, a soft aluminum magnesium silicate mineral, as a nonhalogenated replacement. Sometimes used for sculpting, the clay is used more often in oil drilling to keep the drill bit cool and as an absorbent in cat litter.

The clay is made up of nanometers-thick sheets of the mineral, Bruce notes. When an epoxy resin containing the clay burns, a layer of clay ash builds up on the surface of the material. That layer protects the epoxy resin underneath it from burning further. Bruce is exploring how incorporating different surfactants into the clay boosts the production of this flame-retarding ash layer.

As research on the clay progresses, Bruce and her colleagues will be doing life-cycle assessments of prototypes to determine if clay-based materials are more sustainable than the currently used materials.

“Never did I think I would work with management and political science students on projects that were actually related to my research,” Bruce observes. “We are taking nothing for granted until we determine energy costs, emissions, potential for recycling, and health and environmental impacts. Ultimately, we all want to help make real solutions that industry will be able to rapidly adopt.”

Meanwhile, at the Tuskegee campus in Alabama, IGERT Fellow Vertonica F. Powell-Rose is focusing on developing biobased composites for constructing computer housings. A native of Fayetteville, N.C., Powell-Rose attended Fayetteville State University and graduated in 2006 with a B.S. degree in mathematics and a minor in physics. Now in her third year at Tuskegee, she is finishing a master’s degree on her way to a Ph.D. in materials science and engineering.

Powell-Rose is working with IGERT coinvestigator and materials science and engineering professor Mahesh V. Hosur to study how surface treatments affect woven flax fiber. That’s the material used to make linen. The Tuskegee engineers are coupling mats of the fiber with epoxy resin to make reinforced biocomposites, stacking them into layers, and compression molding them into the desired parts.

The surface treatment removes the natural components of the flax fiber that absorb moisture, Powell-Rose explains. This will help prevent delamination of the layered composite. Besides use in electronics, the material could also be used to make molded parts for automobile interiors, she notes.

“I like the way the IGERT program gives us the ability to look at the electronics issue from a cultural standpoint,” Powell-Rose says. “Oftentimes, given the fact that we are living in the U.S., our scope of world issues and global considerations is limited. With this program we are able to see the damage caused by disposal of electronic devices on a global scale.”

That global disposal problem is what attracted Sara C. Beasley, a first-year Purdue public policy graduate student, to the IGERT program. Her research focuses on determining the most effective way to ensure that electronics are recycled responsibly. She has an undergraduate degree in political science from Purdue and is now studying product end-of-life management.

“The thing I love most about the IGERT program is its practical relevance,” she notes. “A lot of times in political science research it seems like the only people who care about what you say are other political scientists. But in this program I get to work with engineers and economists, as well as with people from industry, nonprofit organizations, and other countries. It is teaching me a lot about how to look at problems from a variety of perspectives.”

Failure to manage the end-of-life stage for electronics appropriately results not only in wasted resources, Beasley says, but also in environmental contamination and adverse effects on human health. The Basel Convention of 1989 and an amendment called the Basel Ban of 1995 were intended to prevent the export of hazardous waste from developed countries to developing countries, she notes.

“Unfortunately, this effort has been virtually ineffective with regard to e-waste,” Beasley says. “The U.S. never ratified the convention, and even in countries that did ratify it, a significant amount of e-waste is still exported either through legal loopholes or lack of enforcement.” Given the failure of formal regulations, she says, companies are being urged to voluntarily commit to using responsible recycling practices.

“Electronics manufacturers want to do the right thing,” Purdue’s Handwerker says. “They want to know the trade-offs being made with upcoming changes and what the impacts are going to be on product reliability, cost, safety, human health, and the environment.

“But it’s not just an engineering problem,” she continues. “It involves people’s behavior, dynamics of social systems, industrial systems, and regulation. Our goal is to bring together all of these disciplines and people to address the complex set of issues related to sustainable electronics.”


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