Development of Nanofiber Reinforced Transparent Composites

This paper focuses on application of co-axial electrospinning technique to the development of nanofiber reinforced transparent composites. Investigations have been done on fabrication and functionalization of the transparent composites with improved mechanical properties, thermal properties and shielding ability for ultraviolet radiations. In the fabrication, PMMA, a polymer with excellent visible light transmittance, is chosen as shell part of the co-axial composite nanofibers, whereas PA-6 with higher melting temperature and better mechanical performance is utilized as core part of the nanofibers. Under proper processing temperature, the shell part of the composite nanofibers melts and forms a resin matrix, whereas the core part maintains original fiber topology and plays a reinforcing role in the resin matrix. In this work, the influence of different contents of the core nanofibers on mechanical properties, thermal properties and visible light transmittance of the transparent composites is investigated. Further investigations are related with functionalization on the transparent composites. After a special treatment, TiO2 nano-particles are added into either the shell or the core part of the electrospun nanofibers, whereas MWCNTs are introduced only into the core nanofibers. These particles are blended with respective polymer solutions before co-axial electrospinning. The resulting core-shell composite nanofibers with the additives are then hot pressed into the nanofiber and the nano additive reinforced composites, which are characterized to study the influence of the additives and their content on the mechanical, thermal, visible light transmittance, and anti-ultraviolet light transmittance performance of the composites. The results indicate that with a minor loss of less than 10% in transparency, the tensile modulus and tensile strength of the transparent PMMA composites can be increased by around 20% higher than the counterparts of the pure PMMA organic glass. The TiO2 nano-particles added in the shell part of the electrospun composite nanofibers exhibit a remarkable performance on UV light transmittance of the transparent composites but lower down visible light transmittance to a relatively large extent. On the contrary, those added in the core part had a reversed effect on anti-UV light performance and on visible light transmittance. A proper amount of MWCNTs added into the PA-6 core can result in a further increase in the mechanical properties of the transparent composites.