NOVELTY - Aligning nanoscale fibers involves: providing network of nanoscale fibers, which is substantially devoid of a liquid; and mechanically stretching the network of nanoscale fibers in first direction.    USE - For aligning nanoscale fibers, useful in making composite materials and articles (claimed), such as electronic devices, electromagnetic interference (EMI) shielding; immediate applications including composite applications for aircraft and thermal management for electronic device package; lightweight high-performance structural materials applications e.g. lightweight-conducting films and current-carrying materials for electronic products; in lightning strike protection, and electronic and energy applications such as high-conducting thin film, and battery and fuel cell electrodes.    ADVANTAGE - The method provides improved nanotube alignment technique for alignment of nanoscale fibers in buckypapers (BP) and carbon nanotubes, by mechanically stretching network of nanoscale fibers that is substantially devoid of liquid, in first direction. During stretching, a supporting medium is used that holds and brings nanotubes closer together in nanotube network to induce nanotube alignment along stretching direction. The supporting medium uniformly and effectively transfers stretching force to nanotubes in buckypaper to realize alignment and avoid nanotube network breakdown under high stretching strains (e.g. stretching strains for achieving high degree of alignment). In addition, supporting medium may provide force to hold nanotube network to avoid BP breaking down due to local nanotube slippage during stretching. The supporting medium comprising flexible polymer film protects and supports nanotube networks in buckypaper during mechanical stretching process to further increases nanotube alignment. The aligned network of nanoscale fibers has Young's modulus of 5-25 GPa and tensile strength of 200-668 MPa; in the direction of nanoscale fiber alignment. No liquid treatment (e.g. solvent or surfactant treatment) of buckypaper or network is necessary to achieve alignment of nanoscale fibers. Thus the method can induce selected orientation of nanoscale fibers by mechanical stretching of buckypapers and/or nanoscale fiber composites that include thermoplastic film, and relies on relatively simple mechanical force, requiring inexpensive materials and equipment to achieve high degree of nanoscale fiber alignment in the buckypaper, which can lead to inexpensive future scaling-up and commercialization. The aligned buckypaper can be impregnated by thermosetting and/or thermoplastic resins, such as epoxy, for fabricating nanocomposites. Use of aligned BP in composites facilitates realizing full potential of carbon nanotubes or nanofiber buckypaper for high mechanical performance and multifunctional applications. When polymeric supporting medium is used, polymer may be infused into nanotube network so that loading can be transferred more uniformly to nanotube network and result in even deformation of BP during stretching process. Hence, in sandwich composites, supporting medium provides large deformation capability and uniform transfer of stretching load to entire nanotube network to induce nanotube alignment. Certain supporting media may be easily thermally decomposed by heating, leaving almost no residue on the buckypaper, thus resulting in thermally stable materials. Hence, purification of stretched BP materials may be achieved by simple thermal burning processes. The method has excellent potential for use in mass production of high-performance nanotube and nanofiber-reinforced polymer composites. In addition to using mechanically stretched buckypaper to provide aligned nanoscale fibers in composites, the method also provides high loading and larger aspect ratios. The aligned nanotubes which are highly anisotropic in nature, can help to achieve strong mechanical properties and high electrical and thermal conductivity; such as alignment of nanoscale fibers in buckypaper allows to utilize exceptional mechanical properties of nanotubes along their axial direction. Also, enhanced contact efficiency between nanotubes allows for realization of more self-assembly and high density packing of nanotubes, and provides improved load transfer in the composites. The mechanically stretched buckypaper provides nanoscale fibers in more compacted form, as well being comprised of longer networks of nanoscale fibers which are capable of being stretched mechanically, and results in increased rope sizes and packing density, as compared to pre-stretched nanotube sheets. The aligned nanoscale fibers can also have tight packing, which is desirable for high loading in composites. Improvement of alignment of nanoscale fibers and loading is desirable factor toward realizing potential of nanotubes for high mechanical, electrical and thermally conductive applications in composites and electronic devices.    DETAILED DESCRIPTION - Aligning nanoscale fibers involves: providing network of nanoscale fibers, which is substantially devoid of a liquid; and mechanically stretching the network of nanoscale fibers in first direction. The network of nanoscale fibers is buckypaper, or nanoscale fibers comprise carbon nanotubes. The method further involves providing supporting medium on or in the network of nanoscale fibers before mechanically stretching, and the step of mechanically stretching stretches both network of nanoscale fibers and supporting medium in first direction; and after stretching, removing supporting medium from the network of nanoscale fibers. The supporting medium comprises flexible thermoplastic material (preferably polyethylene film). The carbon nanotubes have average length of greater than or equal to 1 millimeter. The removing of supporting medium involves thermally decomposing supporting medium, and annealing supporting medium before thermally decomposing. INDEPENDENT CLAIMS are included for the following:    (1) making composite material involving: providing network of nanoscale fibers; mechanically stretching network of nanoscale fibers in first direction to form network of aligned nanoscale fibers; and incorporating network of aligned nanoscale fibers onto or into matrix material; and    (2) article comprising: network of nanoscale fibers, where the network has been mechanically stretched to align at least a portion of the nanoscale fibers, and has a Young's modulus of 5-25 GPa, in direction of nanoscale fiber alignment.