Chemistry and chemical engineering researchers at Virginia Tech and Clemson University have been working for three years with funding from the U.S. Department of Energy to develop new ways to make cheaper, more environmentally friendly carbon-fiber precursor materials. The researchers have made a discovery that makes it possible to create the carbon fiber precursor materials without solvents and potentially to process them into carbon fibers more quickly and cheaply than can be done presently.
Members of the Materials Research Institute (MRI) at Virginia Tech will present their work at the 226th American Chemical Society (ACS) national meeting in New York City Sept. 7-11.
The usual first step in carbon fiber production is the creation of acrylic fibers. These fibers are heated for eight to 10 hours at 200 degrees C, and then at progressively higher temperatures, to produce carbon fibers. Presently, acrylic fibers are spun in solution. "We have developed an acrylic fiber that can be spun from the melt - from 100 percent solids without solvents," says James McGrath, MRI director.
In addition, the researchers have added a molecular component to the acrylic fiber that reacts with ultraviolet (UV) light. "It's expensive to process material for 10 plus hours at very high temperatures. We think we can cut that to one or two hours as a result of including the photocrosslinkable group," says McGrath.
The process needs to be scaled up from the successful laboratory results, he says.
The paper, "Photocrosslinkable acrylonitrile terpolymers as carbon fiber precursors" (Poly 244) will be presented Tuesday, Sept. 9, at 9:30 a.m. in the New York Hilton Sutton North room. It is the first presentation on the synthesis of acrylic fibers with a photo-sensitive monomer. Authors of this paper are MRI post-doctoral associates Thekkekara Mukundan and Vinayak A. Bhanu, chemistry Ph.D. student Kent Wiles, chemical engineering Ph.D. student Michael Bortner, and professors D.G. Baird of chemical engineer and McGrath of chemistry, all at Virginia Tech. Research colleagues from Clemson are chemical engineering professors Dan Edie and Amod Ogale and their students.
Development of lightweight and high strength polymer matrix carbon fiber composites suitable for automotive applications is one of the thrust areas of contemporary applied polymer research. Reduction in the cost of carbon fibers is required to expand their use from the current high tech applications, eg. aerospace and military, to more high volume markets like general purpose automotive composites. It is appropriate to briefly discuss the basic chemistry involved in the currently used technology of making carbon fibers and their melt processible precursors, and how can it be amended to obtain more cost effective carbon fibers. In the present study, the design and synthesis of AN terpolymers containing MA as the major comonomer and acryloyl benzophenone, ABP (< 1 mol%) as the minor comonomer for assisting in the UV induced cross linking is presented. Structural characterization and thermal analysis of the copolymers are reported. Both dynamic and steady shear viscosities have been studied to assess the suitability of these copolymers as melt-processable carbon fiber precursors.
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