{"427761":{"#nid":"427761","#data":{"type":"news","title":"Innovative Method Improves Strength and Modulus in Carbon Fibers","body":[{"value":"\u003Cp\u003ECarbon fibers are stronger and lighter than steel, and composite materials based on carbon-fiber-reinforced polymers are being used in an expanding range of aerospace, automotive, and other applications \u2013 including major sections of the Boeing 787 aircraft. It\u2019s widely believed, moreover, that carbon-fiber technology has the potential to produce composites at least 10 times stronger than those in use today.\u003C\/p\u003E\u003Cp\u003EA research team at the Georgia Institute of Technology has developed a novel technique that sets a new milestone for the strength and modulus of carbon fibers. This alternative approach is based on an innovative technique for spinning polyacrylonitrile (PAN), an organic polymer resin used to make carbon fibers.\u003C\/p\u003E\u003Cp\u003EThe work is part of a four-year, $9.8 million project sponsored by the Defense Advanced Research Projects Agency (DARPA) to improve the strength of carbon-fiber materials. The research was reported recently in the journal \u003Cem\u003ECarbon\u003C\/em\u003E.\u003C\/p\u003E\u003Cp\u003E\u0022By using a gel-spinning technique to process polyacrylonitrile copolymer into carbon fibers, we have developed next-generation carbon fibers that exhibit a combination of strength and modulus not seen previously with the conventional solution-spun method,\u0022 said Satish Kumar, a professor in the Georgia Tech School of Materials Science and Engineering who leads the project. \u201cIn addition, our work shows that the gel-spinning approach provides a pathway for even greater improvements.\u201d\u003C\/p\u003E\u003Cp\u003EKumar explained that tensile modulus \u2013 a measure of stiffness -- refers to the force needed to stretch a material by a given amount. Tensile strength expresses how much force is required to actually break the material.\u003C\/p\u003E\u003Cp\u003EIn gel spinning, the solution is first converted to a gel; this technique binds polymer chains together and produces robust inter-chain forces that increase tensile strength. Gel spinning also increases directional orientation of fibers, which also augments strength. By contrast, in conventional solution spinning, a process developed more than 60 years ago, PAN co-polymer solution is directly converted to a solid fiber without the intermediate gel state and produces less-robust material.\u003C\/p\u003E\u003Cp\u003EThe gel-spun carbon fiber produced by Kumar\u2019s team was tested at 5.5 to 5.8 gigapascals (GPa) \u2013 a measure of ultimate tensile strength \u2013 and had a tensile modulus in the 354-375 GPa range. The material was produced on a continuous carbonization line at Georgia Tech that was constructed for this DARPA project.\u003C\/p\u003E\u003Cp\u003E\u201cThis is the highest combination of strength and modulus for any continuous fiber reported to-date,\u201d Kumar said. \u201cAnd at short gauge length, fiber tensile strength was measured as high as 12.1 GPa, which is the highest tensile-strength value ever reported for a PAN-based carbon fiber.\u201d\u003C\/p\u003E\u003Cp\u003EMoreover, Kumar noted, the internal structure of these gel-spun carbon fibers measured at the nanoscale showed fewer imperfections than state-of-the-art commercial carbon fibers, such as IM7. Specifically, the gel-spun fibers display a lower degree of polymer-chain entanglements than those produced by solution spinning. This smaller number of entanglements results from the fact that gel spinning uses lower concentrations of polymer than solution-spinning methods.\u003C\/p\u003E\u003Cp\u003EKumar and his team convert the gel-spun polymer mix into carbon fibers via a selective treatment process called pyrolysis, in which the spun polymer is gradually subjected to both heat and stretching. This technique eliminates large quantities of hydrogen, oxygen, and nitrogen from the polymer, leaving mostly strength-increasing carbon.\u003C\/p\u003E\u003Cp\u003E\u201cIt\u2019s important to remember that the current performance of solution-spun PAN-based carbon fibers has been achieved after many years of material and process optimization \u2013 yet very limited material and process optimization studies have been carried out to date on the gel-spun PAN fiber,\u201d Kumar said. \u201cIn the future, we believe that materials and process optimization, enhanced fiber circularity, and increased solution homogeneity will further increase the strength and modulus of the gel-spinning method.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cbr \/\u003E\u003Cstrong\u003ECITATION\u003C\/strong\u003E: Satish Kumar et al, \u201cHigh strength and high modulus carbon fibers,\u201d (Carbon, 2015). Carbon, 93, 81-87 (2015). \u0026nbsp;\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E177 North Avenue\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia 30332-0181 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contact\u003C\/strong\u003E: John Toon (404-894-6986) (\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: Rick Robinson\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003ECarbon fibers are stronger and lighter than steel, and composite materials based on carbon-fiber-reinforced polymers are being used in an expanding range of aerospace, automotive, and other applications \u2013 including major sections of the Boeing 787 aircraft. \u0026nbsp;It\u2019s widely believed, moreover, that carbon-fiber technology has the potential to produce composites at least 10 times stronger than those in use today.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Georgia Tech researchers are improving the strength and modulus of carbon fibers."}],"uid":"27303","created_gmt":"2015-07-22 15:34:05","changed_gmt":"2016-10-08 03:19:15","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2015-07-22T00:00:00-04:00","iso_date":"2015-07-22T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"427801":{"id":"427801","type":"image","title":"Improved carbon fiber","body":null,"created":"1449254342","gmt_created":"2015-12-04 18:39:02","changed":"1475895167","gmt_changed":"2016-10-08 02:52:47","alt":"Improved carbon fiber","file":{"fid":"202802","name":"carbon-fibers83a_0.jpg","image_path":"\/sites\/default\/files\/images\/carbon-fibers83a_0_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/carbon-fibers83a_0_0.jpg","mime":"image\/jpeg","size":1192929,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/carbon-fibers83a_0_0.jpg?itok=GH3flQsC"}},"427751":{"id":"427751","type":"image","title":"Improving carbon fiber","body":null,"created":"1449254342","gmt_created":"2015-12-04 18:39:02","changed":"1475895167","gmt_changed":"2016-10-08 02:52:47","alt":"Improving carbon fiber","file":{"fid":"202801","name":"carbon-fibers47.jpg","image_path":"\/sites\/default\/files\/images\/carbon-fibers47_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/carbon-fibers47_0.jpg","mime":"image\/jpeg","size":1115869,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/carbon-fibers47_0.jpg?itok=6pIQalIZ"}}},"media_ids":["427801","427751"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"136","name":"Aerospace"},{"id":"135","name":"Research"}],"keywords":[{"id":"1833","name":"aircraft"},{"id":"610","name":"carbon"},{"id":"136521","name":"carbon fiber"},{"id":"12178","name":"composite"},{"id":"1492","name":"Polymer"}],"core_research_areas":[{"id":"39471","name":"Materials"},{"id":"39491","name":"Renewable Bioproducts"}],"news_room_topics":[{"id":"71881","name":"Science and Technology"}],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}