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Détail de l'auteur
Auteur Zhigang Wang
Documents disponibles écrits par cet auteur
Affiner la rechercheCritical content of ultrahigh-molecular-weight polyethylene to induce the highest nucleation rate for isotactic polypropylene in blends / Wei Shao in Industrial & engineering chemistry research, Vol. 51 N° 49 (Décembre 2012)
[article]
in Industrial & engineering chemistry research > Vol. 51 N° 49 (Décembre 2012) . - pp. 15953–15961
Titre : Critical content of ultrahigh-molecular-weight polyethylene to induce the highest nucleation rate for isotactic polypropylene in blends Type de document : texte imprimé Auteurs : Wei Shao, Auteur ; Yaqiong Zhang, Auteur ; Zhigang Wang, Auteur Année de publication : 2013 Article en page(s) : pp. 15953–15961 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Crystallization kinetics isotactic Résumé : The influence of the addition of low amounts of ultrahigh-molecular-weight polyethylene (UHMWPE) on the crystallization kinetics of isotactic polypropylene (iPP) in iPP/UHMWPE blends has been investigated by means of differential scanning calorimetry (DSC) and polarized optical microscopy. During the nonisothermal crystallization process, the primarily formed UHMWPE crystals serve as heterogeneous nucleating agents for iPP nucleation, whereas during the isothermal crystallization process, UHMWPE is in the molten state, iPP nucleation preferentially occurs at the UHMWPE and iPP phase interfaces, and the spherulitic growth rates are not obviously affected. It is particularly interesting to find a critical UHMWPE content (2.5 wt %) in the blends to induce the highest iPP nucleation rate; however, above the critical UHMWPE content, the iPP nucleation rate slows because of aggregation of the UHMWPE component. A delicately designed DSC measurement provides insight into the nucleation mechanism of iPP at the interfaces between the UHMWPE and iPP phase domains. It is proposed that the concentration fluctuations generated from the unstable inhomogeneous phase interfaces in the iPP/UHMWPE blends promote the formation of nuclei, which eventually enhances the nucleation and overall crystallization rates of the iPP component. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302542x [article] Critical content of ultrahigh-molecular-weight polyethylene to induce the highest nucleation rate for isotactic polypropylene in blends [texte imprimé] / Wei Shao, Auteur ; Yaqiong Zhang, Auteur ; Zhigang Wang, Auteur . - 2013 . - pp. 15953–15961.
Industrial chemistry
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 51 N° 49 (Décembre 2012) . - pp. 15953–15961
Mots-clés : Crystallization kinetics isotactic Résumé : The influence of the addition of low amounts of ultrahigh-molecular-weight polyethylene (UHMWPE) on the crystallization kinetics of isotactic polypropylene (iPP) in iPP/UHMWPE blends has been investigated by means of differential scanning calorimetry (DSC) and polarized optical microscopy. During the nonisothermal crystallization process, the primarily formed UHMWPE crystals serve as heterogeneous nucleating agents for iPP nucleation, whereas during the isothermal crystallization process, UHMWPE is in the molten state, iPP nucleation preferentially occurs at the UHMWPE and iPP phase interfaces, and the spherulitic growth rates are not obviously affected. It is particularly interesting to find a critical UHMWPE content (2.5 wt %) in the blends to induce the highest iPP nucleation rate; however, above the critical UHMWPE content, the iPP nucleation rate slows because of aggregation of the UHMWPE component. A delicately designed DSC measurement provides insight into the nucleation mechanism of iPP at the interfaces between the UHMWPE and iPP phase domains. It is proposed that the concentration fluctuations generated from the unstable inhomogeneous phase interfaces in the iPP/UHMWPE blends promote the formation of nuclei, which eventually enhances the nucleation and overall crystallization rates of the iPP component. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie302542x Effects of sintering on the properties of La0.6Sr0.4Co0.2Fe0.8O3−δ perovskite hollow fiber membranes / Xiaoyao Tan in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010)
[article]
in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2895–2901
Titre : Effects of sintering on the properties of La0.6Sr0.4Co0.2Fe0.8O3−δ perovskite hollow fiber membranes Type de document : texte imprimé Auteurs : Xiaoyao Tan, Auteur ; Zhigang Wang, Auteur ; Kang Li, Auteur Année de publication : 2010 Article en page(s) : pp. 2895–2901 Note générale : Industrial Chemistrey Langues : Anglais (eng) Mots-clés : Separation--Hg(II)--Aqueous Solution--Bulk--Liquid--Membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) hollow fiber membrane precursors were prepared by spinning a starting suspension containing 68.75 wt % LSCF powders, 6.25 wt % polyethersulfone (PESf), and 25.0 wt % N-methyl-2-pyrrolidinone (NMP) at room temperature using deionized water and tape water as the internal and external coagulants, respectively. High temperature sintering was carried out in a range of 1200−1500 °C to study the influences of the sintering process on the properties of the LSCF hollow fiber membranes including the microstructure, crystalline phase, mechanical strength, as well as the oxygen permeability. Mechanical strength of the LSCF hollow fibers increased with increasing sintering temperature and reached a maximum of 115 MPa at 1500 °C sintering temperature. To obtain gastight LSCF hollow fiber membranes, the sintering temperature must be higher than 1250 °C, and the sintering time must be longer than 2 h. However, higher than 1350 °C sintering temperature would facilitate the formation of sulfate impurity phases, resulting in noticeable reduction of oxygen permeation flux. The optimum sintering temperature should be around 1300 °C, and the sintering time should be within the range of 2−4 h to obtain the gastight and high flux LSCF hollow fiber membranes. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901403u [article] Effects of sintering on the properties of La0.6Sr0.4Co0.2Fe0.8O3−δ perovskite hollow fiber membranes [texte imprimé] / Xiaoyao Tan, Auteur ; Zhigang Wang, Auteur ; Kang Li, Auteur . - 2010 . - pp. 2895–2901.
Industrial Chemistrey
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2895–2901
Mots-clés : Separation--Hg(II)--Aqueous Solution--Bulk--Liquid--Membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) hollow fiber membrane precursors were prepared by spinning a starting suspension containing 68.75 wt % LSCF powders, 6.25 wt % polyethersulfone (PESf), and 25.0 wt % N-methyl-2-pyrrolidinone (NMP) at room temperature using deionized water and tape water as the internal and external coagulants, respectively. High temperature sintering was carried out in a range of 1200−1500 °C to study the influences of the sintering process on the properties of the LSCF hollow fiber membranes including the microstructure, crystalline phase, mechanical strength, as well as the oxygen permeability. Mechanical strength of the LSCF hollow fibers increased with increasing sintering temperature and reached a maximum of 115 MPa at 1500 °C sintering temperature. To obtain gastight LSCF hollow fiber membranes, the sintering temperature must be higher than 1250 °C, and the sintering time must be longer than 2 h. However, higher than 1350 °C sintering temperature would facilitate the formation of sulfate impurity phases, resulting in noticeable reduction of oxygen permeation flux. The optimum sintering temperature should be around 1300 °C, and the sintering time should be within the range of 2−4 h to obtain the gastight and high flux LSCF hollow fiber membranes. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901403u Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes / Zhigang Wang in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009)
[article]
in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 510-516
Titre : Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes Type de document : texte imprimé Auteurs : Zhigang Wang, Editeur scientifique ; Naitao Yang, Editeur scientifique ; Bo Meng, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 510-516 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Oxygen Hollow fiber membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite powders having a submicrometer size were synthesized by a sol−gel autocombustion method. From these powders, the gastight LSCF hollow-fiber membranes with a highly asymmetric structure comprising a dense layer of thickness ca. 88 μm integrated with a porous substrate were fabricated in a single step through a phase inversion/sintering technique with a mixture of N-methyl-2-pyrrolidone (NMP) and water as internal coagulant. Oxygen permeation fluxes through the obtained hollow-fiber membranes were measured under air/He gradients at different temperatures. The results indicate that the highly asymmetric hollow-fiber membranes possess an oxygen permeation flux of 0.11−2.19 mL cm−2 min−1 in the temperature range of 650−1000 °C, which is 2.6−10.5 times higher than that of the sandwich-structured hollow-fiber membranes. Oxygen permeation in the hollow-fiber membranes is limited primarily by the surface exchange reactions at lower temperatures, but ionic bulk diffusion will have a rate-limiting effect at temperatures higher than 900 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010462 [article] Preparation and oxygen permeation properties of highly asymmetric La0.6Sr0.4Co0.2Fe0.8O3-a perovskite hollow-fiber membranes [texte imprimé] / Zhigang Wang, Editeur scientifique ; Naitao Yang, Editeur scientifique ; Bo Meng, Editeur scientifique . - 2009 . - P. 510-516.
Chemical engineering
Langues : Anglais (eng)
in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 510-516
Mots-clés : Oxygen Hollow fiber membrane Résumé : La0.6Sr0.4Co0.2Fe0.8O3−α (LSCF) perovskite powders having a submicrometer size were synthesized by a sol−gel autocombustion method. From these powders, the gastight LSCF hollow-fiber membranes with a highly asymmetric structure comprising a dense layer of thickness ca. 88 μm integrated with a porous substrate were fabricated in a single step through a phase inversion/sintering technique with a mixture of N-methyl-2-pyrrolidone (NMP) and water as internal coagulant. Oxygen permeation fluxes through the obtained hollow-fiber membranes were measured under air/He gradients at different temperatures. The results indicate that the highly asymmetric hollow-fiber membranes possess an oxygen permeation flux of 0.11−2.19 mL cm−2 min−1 in the temperature range of 650−1000 °C, which is 2.6−10.5 times higher than that of the sandwich-structured hollow-fiber membranes. Oxygen permeation in the hollow-fiber membranes is limited primarily by the surface exchange reactions at lower temperatures, but ionic bulk diffusion will have a rate-limiting effect at temperatures higher than 900 °C. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8010462