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Zhao J.,University of Sichuan | Zhou T.,University of Sichuan | Zhang J.,University of Sichuan | Chen H.,University of Sichuan | And 3 more authors.
Industrial and Engineering Chemistry Research

In this study, a novel waterborne polyurethane-fluorinated acrylic (WFPU) hybrid emulsion was synthesized and introduced. The cross-linker aziridine was used to enhance the film-forming capacity and mechanical property of WFPU. FTIR and XPS results confirmed that WFPU latex was successfully prepared. WFPU has an excellent hydrophobicity, resulting in an obvious increasing of water contact angle from 58.5° to 92.5°. AFM measurements observed that a continuous polymer film was formed after adding the cross-linker, indicating an excellent film-forming capacity of the cross-linked WFPU. The influence of the amount of the cross-linker on the hydrophobicity and mechanical properties was also studied. Cotton coating experiments visually approved that the cotton hydrophobicity is effectively enhanced by WFPU and the cross-linked WFPU. These results indicated that the cross-linked WFPU containing 30 wt % of fluorinated acrylate and 2.93 wt % of cross-linker has a potential as a coating material for water repellent applications due to providing fantastic hydrophobicity, excellent film-forming capacity, and outstanding mechanical properties. © 2014 American Chemical Society. Source

Zhang J.,University of Sichuan | Zhou T.,University of Sichuan | Xia L.,University of Sichuan | Yuan C.,Longteng Polymer Materials Co. | And 2 more authors.
Journal of Materials Chemistry A

In this study, a carbon-based polypropylene thermoplastic elastomer (PP-elastomer) composite for current collectors of an all-vanadium redox flow battery (VRB) was successfully prepared. The volume resistivity of the PP-elastomer composite was 0.47 Ω cm. Its tensile strength and elongation at break were 6.6 MPa and 250%, respectively. In addition, the good flow property in processing means this composite has potential for the mass industrial production of current collectors. The single cell and the cell stack of a VRB equipped with the composite current collectors were assembled for battery tests, including cyclic voltammetry, long-term performance, long-term stability, and oxidation corrosion. To evaluate the stability and the performance of the cell stack under a long-term operating condition, tests with more than 2300 charge-discharge cycles were carried out. The coulombic efficiency (CE) and voltage efficiency (VE) of the cell stack were maintained at around 93% and 80% during 2300 charge-discharge cycles, and energy efficiency (EE) held at around 75%. The results proved that a VRB equipped with composite current collectors has good stability and performance. Furthermore, long-term corrosion tests indicated that the PP-elastomer composite could endure the strong corrosion of pentavalent vanadium and concentrated sulfuric acid. The composite materials prepared in this study are more suitable than other materials for producing the current collectors. The corrosion resistance of composite materials is much better than that of the graphite, and the mechanism is also discussed. © The Royal Society of Chemistry 2015. Source

Liu X.,University of Sichuan | Zhou T.,University of Sichuan | Liu Y.,University of Sichuan | Zhang A.,University of Sichuan | And 2 more authors.
RSC Advances

cis-Polybutadiene rubber (cis-BR) is one of the typical unsaturated rubbers in mass production and is widely used. However, the detailed mechanism of its cross-linking with peroxides is still unclear so far. In this study, in situ FTIR spectra combined with the powerful PCMD2D and 2D correlation spectroscopy was used to track the detailed cross-linking process. The temperature region of cis-BR cross-linking determined by PCMW2D was within 165-195°C. The temperature with a maximum cross-linking rate was determined at 183°C via PCMW2D, which is identical with DSC. The generation of -•CH- macromolecular free radicals through losing α hydrogens was observed when below 165°C. An abnormal increase of double bonds with trans-1,4-structure during the cross-linking (165-195°C) was observed. An obvious enhancement of -CH2- groups was also found, which indicated that a large number of the double bonds with cis-1,4- and 1,2-structure involved in cross-linking is transformed into -CH2- groups. A 5-step process for the whole cross-linking was inferred from the sequential order of group motions. The first step is DCP decomposition and free radical release. The second step is the generation of trans-1,4-structure due to the internal rotation of the cis-1,4-structure induced by free radicals at α position. The third step is the free radical addition of double bonds with a 1,2-structure, and the fourth is the free radical addition of double bonds with a cis-1,4-structure. The final step is the cross-linking via double coupling of two macromolecular free radicals. In the last step, the free radicals from the cis-1,4-structure also can be probably terminated by a chain transfer. © The Royal Society of Chemistry 2015. Source

Zhang J.,University of Sichuan | Zhou T.,University of Sichuan | Zhao J.,University of Sichuan | Yuan C.,Longteng Polymer Materials Co. | And 4 more authors.
Journal of Applied Polymer Science

In this article, a conductive foam based on a novel styrene-based thermoplastic elastomer called poly(styrene-b-butadiene-co-styrene-b-styrene) tri-block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene-b-butadiene-b-styrene) tri-block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross-linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180°C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30-50 μm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 × 106 to 6.20 × 107 cells/cm3) and a rapid thinning of the cell walls (from 45.3 to 1.4 μm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48-0.09 g/cm3 and the volume resistivity of 3.1 × 103-2.5 × 105 Ω cm can be easily prepared in this study. © 2014 Wiley Periodicals, Inc. Source

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