DuPont Chemist Tim Krizan Formulates “Polymers on the Edge”
by Adrienne Lallo/Lallo Communications
A jet engine — where temperatures spike to 700 degrees Fahrenheit — is no place for an ordinary plastic. As part of the DuPont™ Vespel® Parts and Shapes business, DuPont Technology Associate Timothy Krizan formulates rugged new polyimides for the aircraft engine industry.
Vespel® parts replace plastic, ceramic and metal parts in aircraft engines and wherever friction is undesirable, corrosion is commonplace and pressures are almost unbearable.
Krizan is an organic chemist by training who refers to Vespel® resins as “polymers on the edge.” DuPont produces the complex polymer resin and fabricates parts from these resins to meet manufacturers’ specifications.
Vespel® components perform under conditions where ordinary polymers melt, char or erode. They are lighter than metal and can be flexible while holding their shape. These characteristics enable manufacturers to produce equipment, such as photocopiers and welding torches, that runs more efficiently and reliably, lasts longer and is more economical to operate and maintain. Vespel® also eliminates metal-to-metal contact and reduces the associated noise.
DuPont first introduced high-molecular-weight polyimides in the 1960s as coatings to insulate electrical cables. DuPont™ Kapton® polyimide film continues to provide high temperature resistance as well as weight and space savings in flexible electronic circuits for applications such as aerospace and automotive cable harnesses.
Today, Vespel® polyimides are widely used inside semiconductor etching chambers, where plasma gas carves paths for circuitry onto silicon wafers. Polyimide fixtures that hold the wafers in place resist the corrosive plasma and safeguard the clean environment.
DuPont Physicist Reshapes Way Information Is Shared
by Adrienne Lallo/Lallo Communications
DuPont Research Fellow Graciela Blanchet, a 19-year company veteran, and her co-workers are shepherding the printing world’s transition from the analog to the digital era. The use of laser ablation to print on bendable surfaces using only organic components will literally reshape the way information is displayed, creating a world where information can be shared inexpensively, any time, anywhere.
Lightweight flexible polymeric displays have all sorts of potential uses. According to Graciela, these include radio frequency identification tags such as those used for automatically paying tolls; smart cards; and digital displays that can be rolled up for storage. In addition, other appealing opportunities are advertising – particularly in hard to reach locations — high-resolution proofs that can be easily corrected prior to printing on a press, product information on supermarket shelves and restaurant menus.
One of the more ambitious ideas is electronic paper, “a medium that displays a newspaper or book page and then instantaneously loads the next page when desired,” she suggests.
“Eventually, we envision this technology being printed as easily as newsprint from rolls, and being inexpensive enough that the electronic devices can be thrown away,” Graciela says. “A disposable electronic device is truly novel.” It’s a market expected to be worth billions.
The materials used for printing organic electronic devices have fairly simple structures, borrowing from Graciela’s own pioneering work in color proofing and color filter products. A multi-layer donor film, with ejection, heating and printable layers – i.e. a conductor, dielectric or semiconductor – is sandwiched against a plastic substrate. A laser beam is used to selectively transfer, say, a conducting layer from the donor film onto the plastic substrate.
Printing organic electronic devices is exciting because of its distinct advantages over silicon-based electronics. Stiff silicon requires scrupulously clean rooms and high temperatures. It can cost $3 billion to put a new chip manufacturing facility into production. In contrast, Graciela and her colleagues hope that organic materials may yield to a room temperature, dry and high-speed process at considerably less cost.
DuPont Scientist Works to Improve Automotive Air Bags
Jialin Sun, the DuPont Scientist of the Month, and her team are using their knowledge of Nylon fiber to develop products and solutions for safer airbags. Photo: Ed Lallo/Lallo Photography
by Adrienne Lallo/Lallo Communications
Air bags are quickly becoming just as important a safety asset in cars as seatbelts, and Jialin Sun, the DuPont Scientist of the Month, and her team are using their knowledge of Nylon fiber to develop products and solutions for safer airbags.
According to the National Highway Traffic Safety Administration, the combination of an air bag and a safety belt reduces the risk of serious head injury by 85 percent. In fact, air bag systems have saved more than 8,000 lives since their adoption in the U.S. alone. The air bag must deploy in less time than it takes for an eye blink (approximately 1/10 of a second), generally at a speed of more than 100 m.p.h. when an accident occurs. The resultant speed and pressure require the cushion material to be able to withstand extreme stress and temperature.
DuPont Space Saver Nylon 6,6 fiber can withstand the high mechanical stress and high temperatures. According to Sun, “We have become a leading supplier because of the uniqueness of Nylon 6,6 and our ability to innovate over the years.”
Introduced to the automotive airbag market in the mid-1970’s, Nylon 6,6 remains the preferred material for air bag applications worldwide. In addition to its resistance to stress and temperature, Nylon 6,6 fiber can be packed into small spaces, because it is soft, pliable and tough. DuPont is working to make airbags small enough to fit anywhere, even in a seatbelt.
Sun and her team have also worked closely with customers to develop advanced technologies for use in side curtain airbags, which protect vehicle passengers from side impacts. The side curtain air bag helps to reduce serious injury during SUV and other rollovers.
In addition to Nylon 6,6, many air bags also include DuPont™ Kevlar® brand fiber and DuPont™ Tyvek® protective material, which are used to strengthen and protect airbags, and DuPont™ Hytrel® elastomer, which is used in the deployment system. These are just a few of the more than 65 contributions DuPont has made to improve automotive safety.
According to Sun, safety has always been a priority for DuPont. “DuPont is a safety company because that is our way of doing business,” she notes. “We will never sacrifice safety.” Sun goes on to stress the essential importance of safety in air bags in particular. “DuPont only supplies the best materials for air bags because we know they are intended to save lives.”
Sun and her team are also helping to educate people about automobile safety by participating in the DuPont national auto safety tour called “Get Real Behind the Wheel.” The program, which is aimed at newly licensed drivers, kicked off in May of 2003. Sun and her team spent three weeks building a unit that demonstrates how side curtain air bags inflate.
DuPont Scientist Minshon Chiou Invents Kevlar Lifesaving Technologies
by Adrienne Lallo/Lallo Communications
Indisputably, protective vests help safeguard the lives of law enforcement personnel. Unfortunately, officers wear them inconsistently. Many cite comfort as a significant concern. Others put them on only if they expect a dangerous situation on duty. Only 55 percent report that they strap on their vests as a matter of course.
Minshon Chiou, Advanced Fiber Systems research fellow and DuPont Scientist of the Month for September, hopes to boost that low percentage by providing more comfortable, lighter weight, more protective choices for law enforcement officers facing diverse threats. He and his team at the Spruance site in Richmond, Virginia, combine polymer know-how, fiber science and fabric engineering to develop new safety protection applications for DuPont™ Kevlar® brand fiber.
“We modify the fiber structure to imbue it with newer, better or different attributes such as increased toughness or improved strength,” explains Chiou, who has lent his expertise to the business for 21 years. To help ensure that they deliver exactly what officers require, Chiou and his team of R&D staff and marketing specialists frequently interact with customers, visiting them individually as well as conversing during trade shows, training sessions and symposiums. Such close contact has spurred successful new products like DuPont™ Kevlar® Correctional™, a soft fabric system of 100 percent Kevlar® that provides superior stab resistance for corrections officers.
Chiou and his team recently developed two technologies that could help further shield those who willingly place their own lives at risk to make ours safer.
The first breakthrough, called DuPont™ Kevlar® Multi-Threat technology, will serve law enforcement personnel who report that threats against them are increasing in number, variety and level of danger. Body armor with this new technology will help provide multiple threat protection against gunshots, spike or knife stabbing, and slashing to officers involved in a wide range of duties such as airport security, immigration enforcement, Coast Guard patrol, inmate transport or domestic dispute intervention. In such disparate scenarios, the type of weapon threat is unpredictable. Vests with this patented technology will be lighter, more flexible and less bulky than existing technology typically made of metal or ceramic plate.
The second innovation, patented DuPont™ Kevlar® Comfort XLT™ technology, will deliver significantly improved ballistic performance while allowing vest designs at least 25 percent lighter than garments constructed with the current system of 100 percent Kevlar®. With these two lighter, more comfortable, more protective Kevlar® performance technologies, officers may be more likely to wear their vests on a daily basis and be better able to safely carry out their tasks.
Chiou’s team created both new technologies using a systems approach that will produce better results for body armor manufacturers and law enforcement officers. “We not only engineered the fine structure of the fiber and property of the fabric to meet the expressed needs, but also developed systems solutions to assemble the garments and obtain the best results possible,” explains Chiou. This solutions-based technique delivers vital innovations more quickly to the marketplace and helps ensure that top quality reaches those whose lives literally depend upon it.