This Small Business Technology Transfer Research (STTR) Phase II project has the overall objective of developing a multi-component melt spinning approach to produce a new family of high performance fibers using standard low-cost polymers. The new high-strength and/or high-modulus polymeric fiber is to be made using cutting-edge but commercially available spinning technology and an innovative and previously unexplored set of spinning process parameters. The resulting new fiber will be comparable in performance to other high-performance fibers on the market today, but will cost significantly less. Spinning experiments will be conducted at both the laboratory/bench scale, and at the pilot line level. Experimental fiber spinning lines will be modified to enable consistent fiber manufacturing. Produced fibers will be characterized using a variety of tools (focused ion beam, scanning and transmission electron microscopy, X-ray, tensile, lateral compression, density, differential scanning calorimetry, and dynamic mechanical analysis) to understand the new mechanisms that lead to improved strength and/or stiffness. The spinning conditions which enable these mechanisms will be optimized to meet target strength and/or stiffness goals. The possibility of introducing UV-resistant additives and/or other application-specific components, and any corresponding effects on performance, will also be studied.
The broader impact/commercial potential of this project is based on achieving a performance goal for the new fibers of tenacity > 15 gf/denier and/or an initial modulus of 400 gf/denier or greater. Given the anticipated capability for low-cost high-volume production, these new fibers will have a cost approaching that of standard high tenacity industrial fibers (~ $7/lb) as compared to the typical >$20/lb for specialty high performance fibers such as aramids and high-performance polyethylene (HPPE). The new fiber products will be designed to have a performance above current high-tenacity industrial fibers (HT polyester and nylon) but below current specialty high-performance fibers (aramids, HPPE). The reduced cost for these fibers will result in lower costs over a variety of applications, which will benefit society (for example, by the greater proliferation of cut-resistant apparel and other safety/protective devices). In addition to these economic benefits, the proposed work will provide extensive characterization of nano-scale fibers that will contribute to the scientific understanding of polymeric fiber structure and behavior.
A proprietary nano-engineered melt-extrusion capability has been developed. The ability to control molten polymer domains to diameters below 100nm has been demonstrated. Spinning experiments were conducted at both the laboratory/bench scale, and at the pilot line level. Fiber spinning lines were modified to enable demonstration of consistent fiber manufacturing. Produced fibers were characterized using multiple techniques including speed of sound, DSC, TMA, FIB/SEM/TEM and tensile testing in an attempt to understand new mechanisms that lead to strength and/or stiffness. This new nano-engineered melt-extrusion technology can be exercised in designed experiments to produce industrial fibers with improved performance. Given the anticipated capability for low-cost high-volume production, these new fibers will have a lower cost than current high performance fibers. This reduced cost for fiber and subsequent composite material systems will result in lower cost applications that benefit society by the greater proliferation of ballistic armor, cut resistance apparel and other safety/protective devices. With the first generation of products focused just below current high performance fibers, a second generation of products will compete directly with these fibers. A broader impact will then be the eventual displacement of the environmentally unfriendly solvent based manufacturing of aramids and HPPE with simple and more environmentally friendly melt spinning. In addition to economic and scientific benefits, the work engaged three undergraduate students and four faculty at two universities (Clemson and NC State University).
