A method of forming a composite of embedded nanofibers in a polymer matrix with a high degree of alignment has been created using a nanofiber continuous fiber (NCF) system. This innovation incorporates nanofibers in a plastic matrix forming agglomerates, and then uniformly distributes them by exposing the agglomerates to hydrodynamic stresses that force the agglomerates to break apart. In combination, or additionally, elongational flow is used to achieve small diameters and alignment.
In this system, nanofibers are embedded in polymer matrices in micron-sized fibers, including fibrils with diameters of 100 nm, multiwall nanotubes, single-wall nanotubes, and their various functionalized and derivative forms. Orientation is induced by high shear mixing and elongational flow singly or in combination. The polymer may be removed from the nanofibers, leaving micron-sized fibers of aligned nanofibers.
These micron-sized fibers provide easy handling and distribution of nanofibers for manufacturing into a range of parts for mechanical, electrical, and thermal applications. NCFs can be produced in continuous fiber lengths (1000s of km, for example) to be filament wound, woven, laid up, processed in rows or bundles, or used for thread or yarn to produce a range of products requiring the enhancement from the nanofiber additions. The polymer matrix system can easily be processed into various shapes, or processed with other polymer systems or non-polymeric additions.
The NCFs are a system that can deliver aligned nanotubes for strengthening (including improved impact strength), or electrical or thermal anisotropic features (properties varying in different directions). By extension, the NCF system can also be applied to nanofibers embedded in matrix, and then formed into a tape or film to provide control of distribution and alignment, and to enable a variety of subsequent processing steps.
This work was done by Enrique V. Barrera, Fernando J. Rodriguez-Macias, Karen Lozano, Luis Paulo Felipe Chibante, and David Harris Stewart of Johnson Space Center. For more information, contact the JSC Technology Transfer Office at (281) 483-3809. Refer to MSC-24047-1.