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Carbon dioxide induced crystallization for toughening polypropylene / Jin-Biao Bao in Industrial & engineering chemistry research, Vol. 50 N° 16 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9632-9641 Titre : Carbon dioxide induced crystallization for toughening polypropylene Type de document : texte imprimé Auteurs : Jin-Biao Bao, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur Année de publication : 2011 Article en page(s) : pp. 9632-9641 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Crystallization  Carbon  dioxide Résumé : This study proposes a novel process for significantly toughening isotactic polypropylene (iPP) by finely tuning and controlling the structure and morphology ofiPP. The toughness of injection-molded iPP specimens can be significantly improved by controlled shearing, CO2-induced recrystallization, and adequate cooling without loss of strength. The distribution and structure of the iPP samples before and after toughening were characterized by polarized optical microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, small-angle X-ray scattering, scanning electron microscopy, and differential scanning calorimetry, to investigate the structure―property relationship. Under shear, a high degree of orientation can be obtained with "shish-kebab" crystals formed in the shear zone. During the subsequent CO2 treatment, a crystal network morphology can be formed as a result of an increase in the numbers of primary lamellae and crosshatched subsidiary lamellae, which leads to an increase in toughness. Wide-angle X-ray diffraction patterns indicate that quenching in ice-water of scCO2-treated iPP promotes the formation of nanosized mesomorphic phase domains in the shear zone, which further toughens the iPP. The impact strength of the best toughened iPP sample was found to be over 12 times that of the original sample without loss in tensile strength and modulus. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425207 [article] Carbon dioxide induced crystallization for toughening polypropylene [texte imprimé] / Jin-Biao Bao, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur . - 2011 . - pp. 9632-9641. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9632-9641 Mots-clés : Crystallization  Carbon  dioxide Résumé : This study proposes a novel process for significantly toughening isotactic polypropylene (iPP) by finely tuning and controlling the structure and morphology ofiPP. The toughness of injection-molded iPP specimens can be significantly improved by controlled shearing, CO2-induced recrystallization, and adequate cooling without loss of strength. The distribution and structure of the iPP samples before and after toughening were characterized by polarized optical microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, small-angle X-ray scattering, scanning electron microscopy, and differential scanning calorimetry, to investigate the structure―property relationship. Under shear, a high degree of orientation can be obtained with "shish-kebab" crystals formed in the shear zone. During the subsequent CO2 treatment, a crystal network morphology can be formed as a result of an increase in the numbers of primary lamellae and crosshatched subsidiary lamellae, which leads to an increase in toughness. Wide-angle X-ray diffraction patterns indicate that quenching in ice-water of scCO2-treated iPP promotes the formation of nanosized mesomorphic phase domains in the shear zone, which further toughens the iPP. The impact strength of the best toughened iPP sample was found to be over 12 times that of the original sample without loss in tensile strength and modulus. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425207

Solubility and diffusivity of carbon dioxide in solid-state isotactic polypropylene by the pressure−decay method / Da-chao Li in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7117–7124 Titre : Solubility and diffusivity of carbon dioxide in solid-state isotactic polypropylene by the pressure−decay method Type de document : texte imprimé Auteurs : Da-chao Li, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur Année de publication : 2009 Article en page(s) : pp. 7117–7124 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  dioxide  Solid-state  isotactic  polypropylene  Pressure−decay  method Résumé : The solubility and diffusivity of carbon dioxide (CO2) in the solid-state isotactic polypropylene (iPP) were studied by using the pressure−decay method at temperatures of 373.15, 398.15, and 423.15 K and pressures ranging from 1 to 15 MPa. The solubilities of CO2 in the solid-state and amorphous regions of iPP were both obtained. They increased almost linearly with increasing pressure and decreased with increasing temperature. The Sanchez−Lacombe equation of state (S-L EOS) correlated the solubility in the amorphous regions of the solid-state iPP within 3% average relative deviation in conjunction with a temperature-dependent interaction parameter. The diffusion coefficient of CO2 in the solid-state iPP showed a weak concentration dependence and had an order of magnitude of 10−10−10−9 m2/s in the solid-state iPP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019483 [article] Solubility and diffusivity of carbon dioxide in solid-state isotactic polypropylene by the pressure−decay method [texte imprimé] / Da-chao Li, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur . - 2009 . - pp. 7117–7124. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7117–7124 Mots-clés : Carbon  dioxide  Solid-state  isotactic  polypropylene  Pressure−decay  method Résumé : The solubility and diffusivity of carbon dioxide (CO2) in the solid-state isotactic polypropylene (iPP) were studied by using the pressure−decay method at temperatures of 373.15, 398.15, and 423.15 K and pressures ranging from 1 to 15 MPa. The solubilities of CO2 in the solid-state and amorphous regions of iPP were both obtained. They increased almost linearly with increasing pressure and decreased with increasing temperature. The Sanchez−Lacombe equation of state (S-L EOS) correlated the solubility in the amorphous regions of the solid-state iPP within 3% average relative deviation in conjunction with a temperature-dependent interaction parameter. The diffusion coefficient of CO2 in the solid-state iPP showed a weak concentration dependence and had an order of magnitude of 10−10−10−9 m2/s in the solid-state iPP. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8019483

Step response identification under inherent - type load disturbance with application to injection Molding / Tao Liu in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11572-11581 Titre : Step response identification under inherent - type load disturbance with application to injection Molding Type de document : texte imprimé Auteurs : Tao Liu, Auteur ; Feng Zhou, Auteur ; Yi Yang, Auteur Année de publication : 2011 Article en page(s) : pp. 11572-11581 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Injection  molding Résumé : Motivated by autotuning of injection velocity in an industrial injection molding machine, a step response identification method is proposed for practical application subject to inherent-type load disturbance. Both models of the process and the inherent-type load disturbance can be simultaneously derived from a step test. Identification algorithms are detailed for obtaining the widely used low-order models of first-order plus dead time (FOPDT) and second-order plus dead time (SOPDT). Based on the identified process and disturbance models, a two-degree-of-freedom (2DOF) internal model control (IMC) structure plus feed-forward control is proposed for improving load disturbance rejection. Analytical controller design formulas and tuning guidelines are developed accordingly. A practical application to the velocity control of an injection molding machine is shown to illustrate the effectiveness and merits of the proposed identification method and control strategy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437855 [article] Step response identification under inherent - type load disturbance with application to injection Molding [texte imprimé] / Tao Liu, Auteur ; Feng Zhou, Auteur ; Yi Yang, Auteur . - 2011 . - pp. 11572-11581. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11572-11581 Mots-clés : Injection  molding Résumé : Motivated by autotuning of injection velocity in an industrial injection molding machine, a step response identification method is proposed for practical application subject to inherent-type load disturbance. Both models of the process and the inherent-type load disturbance can be simultaneously derived from a step test. Identification algorithms are detailed for obtaining the widely used low-order models of first-order plus dead time (FOPDT) and second-order plus dead time (SOPDT). Based on the identified process and disturbance models, a two-degree-of-freedom (2DOF) internal model control (IMC) structure plus feed-forward control is proposed for improving load disturbance rejection. Analytical controller design formulas and tuning guidelines are developed accordingly. A practical application to the velocity control of an injection molding machine is shown to illustrate the effectiveness and merits of the proposed identification method and control strategy. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23437855

Supercritical carbon dioxide induced foaming of highly oriented isotactic polypropylene / Jin-Biao Bao in Industrial & engineering chemistry research, Vol. 50 N° 23 (Décembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13387–13395 Titre : Supercritical carbon dioxide induced foaming of highly oriented isotactic polypropylene Type de document : texte imprimé Auteurs : Jin-Biao Bao, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur Année de publication : 2012 Article en page(s) : pp. 13387–13395 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Dioxide  Carbon  Isotactic  Polypropylene Résumé : A highly oriented isotactic polypropylene (iPP) with a shish-kebab crystalline structure is used as a template to achieve nanocellular foams by CO2 foaming in the solid state. The shish-kebab crystalline structure is obtained by tuning injection-molding conditions. Nanocells are generated in amorphous domains confined by shish-kebab crystalline domains which cannot foam. The highly oriented iPP consists of both shish-kebab crystalline structure and spherulites structure and is used to investigate the effect of the crystalline morphology on the cell formation at a given CO2 saturation pressure (15 MPa) and various foaming temperatures (135, 140, 143, and 146 °C). When the foaming temperature is 143 °C, a uniform open nanocellular morphology is obtained. The cell size and cell density both increase with foaming temperature from 135 to 143 °C due to the fact that more crystals are molten, providing more space for cell nucleation and growth. However, when the foaming temperature is increased to 146 °C, the cell size abruptly increases from dozens of nanometers to dozens of micrometers, and the corresponding cell density decreases by several orders of magnitude. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2018228 [article] Supercritical carbon dioxide induced foaming of highly oriented isotactic polypropylene [texte imprimé] / Jin-Biao Bao, Auteur ; Tao Liu, Auteur ; Ling Zhao, Auteur . - 2012 . - pp. 13387–13395. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 23 (Décembre 2011) . - pp. 13387–13395 Mots-clés : Dioxide  Carbon  Isotactic  Polypropylene Résumé : A highly oriented isotactic polypropylene (iPP) with a shish-kebab crystalline structure is used as a template to achieve nanocellular foams by CO2 foaming in the solid state. The shish-kebab crystalline structure is obtained by tuning injection-molding conditions. Nanocells are generated in amorphous domains confined by shish-kebab crystalline domains which cannot foam. The highly oriented iPP consists of both shish-kebab crystalline structure and spherulites structure and is used to investigate the effect of the crystalline morphology on the cell formation at a given CO2 saturation pressure (15 MPa) and various foaming temperatures (135, 140, 143, and 146 °C). When the foaming temperature is 143 °C, a uniform open nanocellular morphology is obtained. The cell size and cell density both increase with foaming temperature from 135 to 143 °C due to the fact that more crystals are molten, providing more space for cell nucleation and growth. However, when the foaming temperature is increased to 146 °C, the cell size abruptly increases from dozens of nanometers to dozens of micrometers, and the corresponding cell density decreases by several orders of magnitude. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2018228

Synthesis of acetyl salicylic acid over WO3/ZrO2 solid superacid catalyst / Cun Zhang in Chemical engineering journal, Vol. 174 N° 1 (Octobre 2011) 

Public ISBD [article]  in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp. 236–241 Titre : Synthesis of acetyl salicylic acid over WO3/ZrO2 solid superacid catalyst Type de document : texte imprimé Auteurs : Cun Zhang, Auteur ; Tao Liu, Auteur ; Hong-Juan Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 236–241 Note générale : Génie chimique Langues : Anglais (eng) Mots-clés : Acetyl  salicylic  acid  Solid  superacid  WO3/ZrO2  catalyst Résumé : Solid superacid WO3/ZrO2 was prepared by co-precipitation of an aqueous zirconyl chloride and ammonium metatungstate solution. The as-prepared catalysts were characterized by using XRD, Laser Raman spectroscopy and BET. Acetyl salicylic acid was synthesized from salicylic acid and acetic anhydride using as-synthesized WO3/ZrO2. The effects of WO3 concentration, reaction time, reaction temperature, molar ratio of reactants, as well as dosage of catalysts on synthesis of acetyl salicylic acid were investigated, and the reaction conditions were therefore optimized. The excellent yield (91.0%) of acetylsalicylic acid was obtained under optimized reaction conditions. The catalyst has been easily recovered and reused repeatedly with a consistent high yield. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010680 [article] Synthesis of acetyl salicylic acid over WO3/ZrO2 solid superacid catalyst [texte imprimé] / Cun Zhang, Auteur ; Tao Liu, Auteur ; Hong-Juan Wang, Auteur . - 2012 . - pp. 236–241. Génie chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 174 N° 1 (Octobre 2011) . - pp. 236–241 Mots-clés : Acetyl  salicylic  acid  Solid  superacid  WO3/ZrO2  catalyst Résumé : Solid superacid WO3/ZrO2 was prepared by co-precipitation of an aqueous zirconyl chloride and ammonium metatungstate solution. The as-prepared catalysts were characterized by using XRD, Laser Raman spectroscopy and BET. Acetyl salicylic acid was synthesized from salicylic acid and acetic anhydride using as-synthesized WO3/ZrO2. The effects of WO3 concentration, reaction time, reaction temperature, molar ratio of reactants, as well as dosage of catalysts on synthesis of acetyl salicylic acid were investigated, and the reaction conditions were therefore optimized. The excellent yield (91.0%) of acetylsalicylic acid was obtained under optimized reaction conditions. The catalyst has been easily recovered and reused repeatedly with a consistent high yield. ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science/article/pii/S1385894711010680

Synthesis of cross - linked, partially neutralized poly (Acrylic Acid) by suspension polymerization in supercritical carbon dioxide / Yazan A. Hussain in Industrial & engineering chemistry research, Vol. 51 N° 35 (Septembre 2012) 

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