Papers by Author: Jian Xu

Abstract: In the present study, the effect of phosphorus flame retardation (FR) agent, 2-carboxyl ethyl (phenyl) phosphinic acid (CEPPA), incorporating phosphate glass (Pglass) on the flame retardation and melt dripping behavior of poly (ethylene terephthalate) (PET) has been investigated. The Pglass/FR-PET nanocomposites (P/FR-PET) were prepared by melt blending. The morphology, thermal degradation behavior and flamability of the nanocomposites were investigated by means of scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index test (LOI) and vertical combustion test. SEM micrographs showed that as the increasing of Pglass contents the morphologies of Pglass in the FR-PET matrix changed from nanoparticles (50 nm to 100 nm) to network structures. The thermal stability of nanocomposites at high temperature increased with the addition of Pglass contents. Meanwhile, the LOI values of the nanocomposites increased from 33.6 for neat FR-PET to 36.1 for 50% P/FR-PET nanocomposites. The vertical combustion test revealed that the P/FR-PET nanocomposites had excellent anti-dripping flame retardant property which can achieve UL-94 V-0 level. The formation of the Pglass network-structured protective layer, which acted as a supporting and heat shield layer, must be crucial for the large reduction in melt dripping. In a word, the experimental results showed that the CEPPA in combination with Pglass has excellent flame retardation and anti-dripping effect.

Abstract: Polyvinylpyrrolidone (PVP)/boehmite nanocomposites fibers were successfully prepared by electrospinning using boehmite sol containing PVP as the spinning solution. Several techniques, including Fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA) and field emission scanning electron microscopy (FE-SEM) were used to characterize their ingredients, thermal properties and morphology. The results showed that PVP concentration exhibited significant effect on the PVP/boehmite nanofibers morphology. With increasing PVP concentration, the morphology changed from beaded, beaded fiber to uniform fiber. These PVP/boehmite nanofibers can be used as good candidates for continuously preparing uniform and compact alumina nanofibers.

Abstract: Alumina nanofibers were fabricated by single-spinneret electrospinning of aluminium nitrate (Al (NO₃)₃)/polyacrylonitrile (PAN) precursor solution, followed by sintering treatment. The Al (NO₃)₃/PAN composite fibers and sintered fibers were characterized by SEM, TG, FTIR and XRD. It is found that the obtained alumina nanofibers show porous external surfaces and hollow sections. Upon calcining the composite fibers at 1000 or 1300 oC, the nanofibers are consisted of α-phased crystalline grains. Sintering temperature plays an important role in controlling the morphology and crystal structure of the nanofibers. A mechanism based on Kirkendall Effect was proposed to explain the formation process of the hollow structure.

Abstract: A pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogel based on Konjac glucomannan(KGM) and methylacrylic acid(MAA) was prepared by free radical polymerization at different concentrations of initiator potassium persulfate (KPS) in presence of crosslinker N,N-methylene-bis-acrylamide (MBA). The chemical structure and rheological properties of hydrogels were characterized by FT-IR and rheometry, respectively. In addition, the swelling behavior of the hydrogels were studied in buffer solution at different pHs.

Abstract: The interfacial structure and interactions of amine-cured epoxy resin (EP) / aluminium oxidie system were investigated in this presentation. The competitive chemisorption of uncured epoxy resin on Al2O3 particles were measured by FTIR and XPS. The interphase structure and the morphology at different depths of the broken-surface of the samples were characterized by XPS and SEM. The results showed that the nitrogenous molecules in the system formed the adsorbed monolayers on the interface based on the coupling interaction of the adsorption and cure. The composition, binding energy and chemical properties of the interphase deviated considerably from that of the bulk.

Abstract: Large area well-aligned ZnO nanowire arrays have successfully been synthesized on an unconventional substrate: stainless-steel mesh at a low growth temperature of 400oC. The as-grown ZnO nanowires have uniform diameters about 20 nm and a strong UV peak was observed in photoluminescence spectra. The growth method provides a novel way to produce high quality ZnO nanowire arrays, and can be also used to direct the controllable growth of other nanomaterials.