Optical Properties of Transparent Resins with Electrospun Polymer Nanofibers

Model composites have been made using electrospun Nylon 6,6 nanofibers with diameters of ~100 nm. Resins used include both transparent epoxy and vinyl ester resins. Optical measurements using a white light source have been made to evaluate the degree of light transmission, haze, and clarity for the composites. A simple model describing the transmission of light through the composite specimen has been developed. This model relates fiber volume fraction, fiber diameter, indices of refraction of both fiber and matrix, and sample thickness to the percentage of light transmitted. The model demonstrates that submicron fiber diameters are necessary in order to maintain a high degree of transparency. Predictions of the model are in good agreement with experimental data. The work shows that processing issues such as resin wet-out of the nanofiber fabric and mitigation of void formation are key factors to obtaining clear nanofiber composites.