ABSTRACT
Hydrophobic and breathable nanofiber membranes have attracted considerable attention owing to their applications in various fields. In this study, we fabricated superhydrophobic and breathable nanofiber membranes using solution blow spinning. We optimized the spinning process parameters by analyzing their effects on the structure and properties of the nanofiber membranes. And the nanofiber membranes achieved superhydrophobicity through hydrophobic modification treatment. The average fiber diameter and pore size of the obtained membrane were 0.51 and 13.65 µm, respectively. The membranes exhibited superhydrophobicity, breathability, and mechanical properties: water vapor transmission of 12.88 kg/m2/day, air permeability of 10.97 mm/s, water contact angle of 150.92°, maximum tensile stress of 5.36 MPa, and maximum elongation at break of 12.27%. Additionally, we studied the impact of heat treatment on the nanofiber membranes. The membranes prepared in this study can be applied to protective garments, outdoor clothing, antifouling materials, etc. Because of its relatively higher production efficiency, solution blow spinning is a prospective method for producing functional nanofibers.
ABSTRACT
A batch of potassium lithium niobate (KLN) crystals with different compositions were grown by using TSSG technique. Samples with three different compositions were well polished. By using near infrared cw:Ti-sapphire laser, their Second Harmonic Generation (SHG) properties were investigated. The results showed that the SHG effect is related to the composition of the samples, and their frequency-doubling efficiency enhanced with the raise of Li ions content in the crystal. By using infrared Raman technique, the properties of nonlinear lattice vibration of thee samples were investigated, and the character of Raman spectrum were analyzed, as well the effect of composition on the SHG properties were discussed. The analysis results showed the striking effects of Li content for these Raman peaks. For KLN sample with small Li content, the three character peaks belonged to [NbO6]7- octahedron show simple peak. With the raise of Li content in crystal, the peaks belonged to v2 mode were partly split, and the peak belongs to v5 mode was broadened. When the Li content approach to the chemical composition KLN crystal, and the structure of [NbO6]7- octahedron is almost to be disorganized, the peaks belonged to v5 mode were split, and the peaks belonged to v1 mode and v2 mode were partly split also, with more distinct weak peaks in the wavelength range of 100-400 cm(-1). These effects were caused by the raise of Li content, which leads to the severer aberrance of [NbO6]7- octahedron in KLN crystal, and disturbing the lattice vibration of the octahedron. This phenomenon is agreed with the nonlinear properties of potassium lithium niobate crystal.
