Qiaoling Li

Mechanical Properties and Flame Retardancy Research of Montmorillonite Intercalate Polyamide 66 Composites

A series of exfoliated nanocomposites or microcomposites have been fabricated with different organophilic montmorillonite (OMMT) loading via in situ intercalation polymerization and melt intercalation. Their structure and mechanical properties were investigated and compared with XRD and other advanced facilities systematically. Flame retardancy was evaluated by conventional limiting oxygen index (LOI) and char residue ratio. Experiment results shows that fabricated technology have unobvious influence on micro-structure, tensile strength and tensile modulus of PA66/OMMT composites. On the contrary, the alteration of OMMT loading cause dramatic change on both mechanical performance and flame retardancy. The maximum tensile strength of PA66/OMMT composites is 106 MPa with 3 wt% OMMT loading. The addition of OMMT enhances obviously the mechanical property and flame retardancy of PA66.

Synthesis and Microwave Absorption Properties of BaTiO3-polypyrrole Composite

BaTiO3 powders are prepared by sol-gel method by cotton template. Polypyrrole is prepared by chemical oxidation route in the emulsion polymerization system. Then BaTiO3-polypyrrole composites with different mixture ratios are prepared by as-prepared material. The structure, morphology, and properties of the composites are characterized with Infrared spectrum, X-ray diffraction, scanning electron microscope, and net-wok analyzer. The complex permittivity and reflection loss of the composites are measured at different microwave frequencies in S-band and C-band (0.03–6 GHz) employing vector network analyzer model PNA 3629D vector. The effect of the mass ratio of BaTiO3 to polypyrrole on the microwave loss properties of the composites is investigated. A possible microwave absorbing mechanism of BaTiO3-polypyrrole composite is proposed. The BaTiO3-polypyrrole composite can find applications in suppression of electromagnetic interference and reduction of radar signature.

Synthesis of magnetic photocatalyst and sensitization properties of polypyrrole

Abstract In order to solve the difficulty of separation and recycling of TiO2 and its lower utilization of solar radiation, a new type of TiO2 photocatalyst, which was sensitized by polypyrrole (PPy) and carried by self-made modified Fe3O4, named PPy-TiO2/M-Fe3O4, was fabricated successfully by combining suspension dispersion and in situ polymerization. The structure of photocatalyst and Fe3O4 was characterized using X-ray diffraction, the Fourier transmission infrared spectrometer, and scanning electron microscopy. Light response property was tested by ultraviolet-visible diffuse reflectance spectra. Photocatalytic activity was evaluated with methyl orange as the degradation substance under different light radiation. Magnetic recovery property was investigated by using vibrating sample magnetometer and gravimetric analysis methods. The results showed that due to sensitization of PPy, the light response scope of PPy-TiO2/M-Fe3O4 was broadened to 451 nm and the degradation rate of methyl orange had been increased by 32.5% under the same conditions. Meanwhile, the recovery rate of PPy-TiO2/M-Fe3O4 remained above 97.9% after five cycles.

Photocatalysis of TiO2 Sheets Prepared by Templating Filter Paper

Titanium dioxide sheet photocatalysts composed of interwoven microstrips were successfully synthesized using filter paper as templates. The synthesized samples were characterized by means of Fourier transform infrared spectroscopy, surface area analyzer, thermogravimetric analysis, powder X-ray diffraction, and scanning electron microscopy. The photocatalytic activities of the samples were evaluated by the degradation of methyl orange in an aqueous solution under UV-illumination. The results demonstrated that the paper-like TiO2 sheets with the optimum proportion of anatase/rutile (10/1) had the highest photoactivity. And the presence of the filter paper fiber can improve the crystallinity, raise the anatase-rutile transformation temperature and contribute to the formation of being paper-like. A detailed formation mechanism for TiO2 sheets is proposed.

Preparation of MnxNi0.5-xZn0.5Fe2O4 Nanorods by the Co-precipitation Method

MnxNi0.5−xZn0.5Fe2O4 nanorods were successfully synthesized by the thermal treatment of rod-like precursors that were fabricated by the co-precipitation of Mn2+, Ni2+, and Fe2+ in the lye. The phase, morphology, and particle diameter were examined by the X-ray diffraction and transmission electron microscopy. The magnetic properties of the samples were studied using a vibrating sample magnetometer. The results indicated that pure Ni0.5Zn0.5Fe2O4 nanorods with a diameter of 35 nm and an aspect ratio of 15 were prepared. It was found that the diameter of the MnxNi0.5−xZn0.5Fe2O4 (0≤x≤0.5) samples increased, the length and the aspect ratio decreased, with an increase in x value. When x = 0.5, the diameter and the aspect ratio of the sample reached up to 50 nm and 7−8, respectively. The coercivity of the samples first increased and then decreased with the increase in the x value. The coercivity of the samples again increased when the x value was higher than 0.4. When x = 0.5, the coercivity of the MnxNi0.5−xZn0.5Fe2O4 sample reached the maximal value (134.3 Oe) at the calcination temperature of 600°C. The saturation magnetization of the samples first increased and then decreased with the increase in the x value. When x = 0.2, the saturation magnetization of the sample reached the maximal value (68.5 emu/g) at the calcination temperature of 800 °C.