Electrospun Nanocomposite Fibers of Polycarbonate- and Taurine-Modified Boehmite Nanoparticles: What Can Be Learned from Structural and Thermal Investigations?

Though the reinforcing properties of inorganic particles in thermosetting nanocomposites have been exploited, the integration of nanoparticles continues to be challenging in terms of their homogeneous distribution and their manipulation, which can contribute to occupational hazards. Due to second encapsulations of nanoparticles, electrospun nanocomposite fibers containing nanoparticles might be an alternative for overcoming these issues, as the nonwoven fibers contain nanoparticles allowing for safer manipulation. Here, the morphology and the thermal properties of electrospun polycarbonate fibers containing taurine-modified boehmite nanoparticles (BNPs) are investigated by means of small- and wide-angle X-ray scattering as well as fast scanning and temperature-modulated fast scanning calorimetry for the first time. The latter techniques allow the investigation of the thermal properties of single fibers at heating rates of up to 104 K s–1 keeping their structure intact. An analysis of the scattering data reveals a porous structure of the fibers. The porous structure is quantified regarding the pore volume and the pore size. A constant amount of aggregation is found even for the highly BNP-loaded fibers. Thermal analysis of the fibers reveals a rigid amorphous fraction (RAF), where it is known that the RAF determines the properties of a nanocomposite to a large extent. For the fibers, the RAF amounts up to 40 wt %, which is essentially higher compared to equally formulated PC/BNP composite cast films. The RAF, in the case of fibers, is not only due to the presence of particles in the polymer but also due to the orientation effects induced by the electrospinning process.