Papers by Author: Zhe Wen Han

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Authors: Guang Yang, Dan Dan Chen, Kan Zhang, Xiao Yun Liu, Xin Xin Li, Qi Xin Zhuang, Zhe Wen Han
Abstract: A series of composites of Polyaniline (PANI) and Polybenzobisoxazole (PBO) nanocomposites were prepared with different PANI compositions. The methanesulfonic acid (MSA) was used as dopant and solvent. The structures and morphology of the obtained nanocomposites were fully characterized by FT-IR, TGA, SEM and TEM. The effect of mass fractions of PANI, temperature and frequency on the dielectric property was studied. The PANI exhibited highly homogeneous dispersion in PBO matrix. The dielectric constants of the composites increased with PANI content and the testing temperature and decreased with frequency.
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Authors: Zhong Xie, Qi Xin Zhuang, Xiao Yun Liu, Jun Qian, Zhe Wen Han
Abstract: The apparent reactivity ratios of hexafluoropropylene (HFP)/vinylidene fluoride (VDF) emulsion copolymerization were studied by nonlinear fitting according to the copolymer composing equation, which, according to the calculation, are 1.88 and 0.86 respectively. The constitution of mixed gaseous monomers was measured through the gas chromatography. The copolymer compositions before and after reaction were measured by 19F-NMR. The calculated contents of VDF and HFP have nice accordance with the results from 19F-NMR analysis, which demonstrates that the method reported here is fairly reliable, and shed a light on the industry-scale consideration for the emulsion copolymerization of HFP and VDF.
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Authors: Qian Fu, Xiao Yun Liu, Qi Xin Zhuang, Jun Qian, Zhe Wen Han
Abstract: As a kind of rig-rod-like polymer, poly(p-phenylene benzobisoxazole) (PBO) has received great interest because of its excellent mechanical properties and good thermal stability. The use of PBO materials, however, is limited due to its low sunlight stability. In this study, photolysis of PBO films was studied by infrared spectroscopy and molecular mass determination. It found that at the beginning of photolysis, the I.V. values of PBO almost did not changed. Then, it underwent fast decrease stage. Moreover, PBO degrade slowly in N2 atmosphere than in air atmosphere. The most likely photo-degradation mechanism was put forward. Attempts to stabilize PBO from photolysis were also investigated. It found that heat treatment could alleviate photo-degradation speed of PBO. Traditional light stabilizers showed a marginal effect on photolysis of PBO, whereas ferrocene dimethanol behaved better effect on the photo-stabilization of PBO.
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Authors: Rong Biao Liu, Xin Xin Li, Jun Qian, Zhe Wen Han
Abstract: PBO (p-phenylene benzobisoxazole) short fibers, attached fine fibrils that are called PBO pulp, may precipitate directly from stirred PBO/methanesulfonic acid (MSA) solution by the use of water coagulant in fibrous pulp form. Scanning electron micrographs show that the precipitated PBO pulps have a ribbon-like structure similar to Kevlar pulps. The thermalgravimetric analysis (TGA) show there were no appreciable mass changes until 550 °C in the air. The process yields PBO pulps with different specific surface areas (SSA) depending on the stirring speed, stirring time and the concentration of the PBO/MSA solution. High SSA PBO pulps can be produced by increasing the stirring speed, prolonging the stirring time and reducing the concentration of the PBO/MSA solution.
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Authors: Yong Chen, Jun Qian, Qi Xin Zhuang, Zhe Wen Han
Abstract: Multiwalled carbon nanotube (MWCNT) was subjected a copolymerization reaction with 4, 6-diaminoresorcinol salt (DAR•2HCl) and terephthalic acid (TA) in polyphosphoric acid (PPA) by Friedel-Crafts acylation reaction without any acid treatment or modification. The structure and morphology of the as-prepared poly (p-phenylene benzobisoxazole) (PBO)/MWCNT nanocomposites were characterized by X-ray diffraction (XRD) and scanning electronic microscope (SEM). The SEM images indicated that MWCNTs can disperse in PBO matrix uniformly without agglomeration and MWCNTs have been introduced into PBO matrix by covalent bonding via Friedel-Crafts acylation between MWCNTs and TA.
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