Controllable Preparation Of "TiO Nanofibers And Its Effect On Interlaminar Fracture Toughness Of Composites

Weak performance between layers is one of the bottleneck factors that constrained the applications of laminated composite under high load conditions. In this research, a new style of nanofiber sheets was fabricated. The cracking nanofiber sheets possess large specific surface area, slice and porous structure characterization. This research was focused on the preparation of "crack" TiO2 nanofiber sheets. Glass substrates were used as nanofiber collector and PVAc/TiO2 solution was used as TiO2 precursor, PVAc was removed by calcination and finally the cracking TiO2 nanofiber sheets were fabricated and deposited on the glass substrate. The effects of TiO2 sol contents, steam treatment time, electrospinning process parameters and calcination temperatures on the fibrous structure, the size of cracked sheets, and the proportion of crevice area were investigated. 20.8 wt.%TiO2 sol concentration and 300s steam treat time were suitable to fabricate good fibrous structure. Higher voltage and longer electrospinning time lead the nanofiber membranes to have a larger average crack sheet size and crevice proportion. The effect of calcination temperature on crack mechanism of nanofiber membrane was investigated. The results showed that the crack formation and evolution rules of the cracked TiO2 nanofiber membrane were attributed to the decomposition of organic chemical components and the TiO2 crystallization. It is expected that the cracked inorganic nanofiber membranes have the potential to be a new pattern of high efficiency composite interlayer modification material. The chemical compositions, crystallization properties and morphologies of the TiO2 nanofibers were characterized using Thermosgravimetry-differential scanning calorimetry (TG-DSC), Fourier transformation infrared spectrometer (FTIR), X-ray diffraction (XRD) and Environment scanning electron microscope (ESEM).The interlaminar fracture toughness of composites with cracked nanofiber sheets interleaved in the laminates was studied, and the method for the sheets to be deposited on the glass fiber was explored. The results showed that by covering the glass fiber with TBT before electrospinning and by steaming the glass fiber with cracked nanofiber sheets can make a good adhesion; the microstructure analysis also proved that after this kind of treatment, the crack sheets can withstand the impact of the resin flow. The composites with cracked nanofiber sheets interleaved in the laminates were prepared using unsaturated polyester resin and glass fiber fabric through import vacuum technology. And the interlaminar fracture toughness of materials was tested, the results showed that compared with the blank sample, the composites interleaved with crack sheets fabricated with spinning time of 3h had an improvement of 92.07%, and fracture surface had been analyzed. The crack propagation path had been discussed, blank sample showed a relative smooth fracture path while the modified sample showed twists fracture path. The study of interlaminar fracture toughness of composites with cracked nanofiber sheets of different thickness showed that as the thickness increased, the value of interlaminar fracture toughness had an increasement.