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Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor / Zhendong Liu in Industrial & engineering chemistry research, Vol. 50 N° 21 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11853–11862 Titre : Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor Type de document : texte imprimé Auteurs : Zhendong Liu, Auteur ; Yangcheng Lu, Auteur ; Bodong Yang, Auteur Année de publication : 2011 Article en page(s) : pp. 11853–11862 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Microreactor Résumé : In this work, a new controllable and continuous free radical polymerization process was developed and characterized in a coaxial capillary microreactor. In this process, the monomer solution was first dispersed into monodispersed droplets followed by thermal-initiated polymerization in the following capillary immersed in an oil bath. Poly(butyl acrylate) prepared in this microreactor possessed a much higher average molecular weight (Mn) and far lower polydispersity index (PDI) than that produced in a typical stirred vessel. The microreactor method possesses two unique advantages which allow for the optimization of the free radical polymerization process. First, the use of highly monodispersed droplets as polymerization units ensures that the polymerization process occurs uniformly in each individual droplet. Second, the small droplet size, on the order of several hundred micrometers, greatly enhances heat transfer efficiency with no heat accumulation within the droplets during polymerization. A simplified numerical simulation was used to show the superiority of the microreactor in effectively removing polymerization heat due to the miniaturization of the droplets to submillimeter scale. Simulation results also demonstrated that, in contrast to polymerization processes occurring in macroreactors, the polymerization conducted in the microreactor proceeded in a nearly isothermal condition. Experimental results in the microreactor showed that the molecular weight distribution was mainly determined by the size of the droplet, while the molecular weight of the polymer could be adjusted by changing the reaction temperature and 2,2-azobis(isobutyronitrile) concentration. This type of microreactor can potentially be applied to research involving the mechanisms of highly exothermic free radical polymerization processes and can also be used as an efficient tool for their controllable preparation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201497b [article] Controllable preparation of poly(butyl acrylate) by suspension polymerization in a coaxial capillary microreactor [texte imprimé] / Zhendong Liu, Auteur ; Yangcheng Lu, Auteur ; Bodong Yang, Auteur . - 2011 . - pp. 11853–11862. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 21 (Novembre 2011) . - pp. 11853–11862 Mots-clés : Microreactor Résumé : In this work, a new controllable and continuous free radical polymerization process was developed and characterized in a coaxial capillary microreactor. In this process, the monomer solution was first dispersed into monodispersed droplets followed by thermal-initiated polymerization in the following capillary immersed in an oil bath. Poly(butyl acrylate) prepared in this microreactor possessed a much higher average molecular weight (Mn) and far lower polydispersity index (PDI) than that produced in a typical stirred vessel. The microreactor method possesses two unique advantages which allow for the optimization of the free radical polymerization process. First, the use of highly monodispersed droplets as polymerization units ensures that the polymerization process occurs uniformly in each individual droplet. Second, the small droplet size, on the order of several hundred micrometers, greatly enhances heat transfer efficiency with no heat accumulation within the droplets during polymerization. A simplified numerical simulation was used to show the superiority of the microreactor in effectively removing polymerization heat due to the miniaturization of the droplets to submillimeter scale. Simulation results also demonstrated that, in contrast to polymerization processes occurring in macroreactors, the polymerization conducted in the microreactor proceeded in a nearly isothermal condition. Experimental results in the microreactor showed that the molecular weight distribution was mainly determined by the size of the droplet, while the molecular weight of the polymer could be adjusted by changing the reaction temperature and 2,2-azobis(isobutyronitrile) concentration. This type of microreactor can potentially be applied to research involving the mechanisms of highly exothermic free radical polymerization processes and can also be used as an efficient tool for their controllable preparation. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201497b

Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device / Bodong Yang in Industrial & engineering chemistry research, Vol. 51 N° 26 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9016-9022 Titre : Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device Type de document : texte imprimé Auteurs : Bodong Yang, Auteur ; Yangcheng Lu, Auteur ; Guangsheng Luo, Auteur Année de publication : 2012 Article en page(s) : pp. 9016-9022 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fluid  mechanics  Microfluidics  Microsphere  Preparation Résumé : A thermal-initiated polymerization procedure is described for the controlled preparation of monodispersed polyacrylamide (PAM) hydrogel microspheres. A coaxial microfluidic device was designed to disperse uniform drops (∼500 μm) of acrylamide monomer aqueous solution into n-octane. Using a delay loop immersed into a heat bath, the polymerization is initiated and carried out in separate droplets. Combining the improvement of heat transfer in the microfluidic device and the sufficient addition of n-octane, the controllable preparation can still be achieved at 95 °C, much higher than 20-60 °C as reported prevalently. Herein, the PAM microspheres can be prepared within 2 min or less, with the CV of diameter less than 4%. Furthermore, based on this controllable reaction platform, PAM microspheres were prepared at various reaction temperatures (higher than 90 °C) and monomer solution compositions to investigate the fundamental rules of controlling on their skeleton structure and absorbent capacity in deionized water. DEWEY : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107459 [article] Controllable preparation of polyacrylamide hydrogel microspheres in a coaxial microfluidic device [texte imprimé] / Bodong Yang, Auteur ; Yangcheng Lu, Auteur ; Guangsheng Luo, Auteur . - 2012 . - pp. 9016-9022. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 26 (Juillet 2012) . - pp. 9016-9022 Mots-clés : Fluid  mechanics  Microfluidics  Microsphere  Preparation Résumé : A thermal-initiated polymerization procedure is described for the controlled preparation of monodispersed polyacrylamide (PAM) hydrogel microspheres. A coaxial microfluidic device was designed to disperse uniform drops (∼500 μm) of acrylamide monomer aqueous solution into n-octane. Using a delay loop immersed into a heat bath, the polymerization is initiated and carried out in separate droplets. Combining the improvement of heat transfer in the microfluidic device and the sufficient addition of n-octane, the controllable preparation can still be achieved at 95 °C, much higher than 20-60 °C as reported prevalently. Herein, the PAM microspheres can be prepared within 2 min or less, with the CV of diameter less than 4%. Furthermore, based on this controllable reaction platform, PAM microspheres were prepared at various reaction temperatures (higher than 90 °C) and monomer solution compositions to investigate the fundamental rules of controlling on their skeleton structure and absorbent capacity in deionized water. DEWEY : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26107459

Heat-transfer performance of a liquid-liquid microdispersed system / Kai Wang in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9754–9758 Titre : Heat-transfer performance of a liquid-liquid microdispersed system Type de document : texte imprimé Auteurs : Kai Wang, Auteur ; Yangcheng Lu, Auteur ; Huawei Shao, Auteur Année de publication : 2009 Article en page(s) : p. 9754–9758 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Performance  Liquid-liquid  Microdispersed  system Résumé : In this work, the heat-transfer performance of liquid−liquid microdispersed systems was tested for the first time with a microdispersion contactor named a membrane dispersion minicontactor and octane/water as the working system. The volumetric heat-transfer coefficients ranging from 5 to 25 MW/(m3·°C) were obtained, which were 15−20 times higher than that of the conventional dispersion heat-transfer methods. The heat-transfer Murphree efficiencies, defined to evaluate the heat-transfer performance, reached 85−99% for the microdispersed system with residence times less than 0.1 s. By introducing the two parameters of Ca number and oil volumetric fraction, a semiempirical model for predicting the volumetric heat-transfer coefficient has been developed, which fits the experimental results very well. Furthermore, the similarity between the heat and mass transfer in the microdispersed system was demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005484 [article] Heat-transfer performance of a liquid-liquid microdispersed system [texte imprimé] / Kai Wang, Auteur ; Yangcheng Lu, Auteur ; Huawei Shao, Auteur . - 2009 . - p. 9754–9758. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9754–9758 Mots-clés : Performance  Liquid-liquid  Microdispersed  system Résumé : In this work, the heat-transfer performance of liquid−liquid microdispersed systems was tested for the first time with a microdispersion contactor named a membrane dispersion minicontactor and octane/water as the working system. The volumetric heat-transfer coefficients ranging from 5 to 25 MW/(m3·°C) were obtained, which were 15−20 times higher than that of the conventional dispersion heat-transfer methods. The heat-transfer Murphree efficiencies, defined to evaluate the heat-transfer performance, reached 85−99% for the microdispersed system with residence times less than 0.1 s. By introducing the two parameters of Ca number and oil volumetric fraction, a semiempirical model for predicting the volumetric heat-transfer coefficient has been developed, which fits the experimental results very well. Furthermore, the similarity between the heat and mass transfer in the microdispersed system was demonstrated. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8005484

Improving selectivity of temperature-sensitive exothermal reactions with microreactor / Kai Wang in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4683–4688 Titre : Improving selectivity of temperature-sensitive exothermal reactions with microreactor Type de document : texte imprimé Auteurs : Kai Wang, Auteur ; Yangcheng Lu, Auteur ; Huawei Shao, Auteur ; Guangsheng Luo, Auteur Année de publication : 2008 Article en page(s) : p. 4683–4688 Note générale : Bibliogr. p. 4688 Langues : Anglais (eng) Mots-clés : Temperature-sensitive  exothermal  reaction;  Cyclohexanecarboxylic  acid;  Oleum Résumé : The selectivity of temperature-sensitive exothermal reaction, especially for a fast reaction system, is hard to control in chemical synthesis process. Traditionally, reducing the reaction temperature is applied to control byproduct. Nowadays, the confinement of the reaction temperature can be released by using microreactors. To demonstrate this, the fast exothermal reaction between cyclohexanecarboxylic acid and oleum was chosen as an experimental system in this work. An adiabatic micropore dispersion capillary reactor was developed to control the reaction selectivity at relatively high temperature. The results showed that 5−30 μm dispersed scale of oleum was reached in this microreactor, and nearly 100% selectivity was obtained at a relatively high product temperature, 50−60 °C, with 100% conversion of oleum. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800318q [article] Improving selectivity of temperature-sensitive exothermal reactions with microreactor [texte imprimé] / Kai Wang, Auteur ; Yangcheng Lu, Auteur ; Huawei Shao, Auteur ; Guangsheng Luo, Auteur . - 2008 . - p. 4683–4688. Bibliogr. p. 4688 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4683–4688 Mots-clés : Temperature-sensitive  exothermal  reaction;  Cyclohexanecarboxylic  acid;  Oleum Résumé : The selectivity of temperature-sensitive exothermal reaction, especially for a fast reaction system, is hard to control in chemical synthesis process. Traditionally, reducing the reaction temperature is applied to control byproduct. Nowadays, the confinement of the reaction temperature can be released by using microreactors. To demonstrate this, the fast exothermal reaction between cyclohexanecarboxylic acid and oleum was chosen as an experimental system in this work. An adiabatic micropore dispersion capillary reactor was developed to control the reaction selectivity at relatively high temperature. The results showed that 5−30 μm dispersed scale of oleum was reached in this microreactor, and nearly 100% selectivity was obtained at a relatively high product temperature, 50−60 °C, with 100% conversion of oleum. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800318q

Preparation of monodispersed uniform silica spheres with large pore size for fast adsorption of proteins / Zheng Zhai in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4162–4168 Titre : Preparation of monodispersed uniform silica spheres with large pore size for fast adsorption of proteins Type de document : texte imprimé Auteurs : Zheng Zhai, Auteur ; Yujun Wang, Auteur ; Yangcheng Lu, Auteur Année de publication : 2010 Article en page(s) : pp. 4162–4168 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Adsorption  Pore  size  Preparation Résumé : In this paper, a “temperature-induced gelation” method, combined with microfluidic flows, has been developed to synthesize the uniform silica spheres with large pore structures for the fast adsorption of bovine serum albumin (BSA). The reversible-thermosentive property of methylcellulose (MC) and auxiliary function of poly(ethylene glycol) (PEG) were introduced to realize a fast gelation in a coaxial microfludic device. The effects of temperature and MC concentration on the gelation process were investigated by monitoring the change of viscosity of sol system over time. The silica spheres with different morphologies of internal structure were synthesized by adjusting the concentration of MC. The prepared silica spheres had large pore volumes (>2.0 mL/g) and an average mesopore diameter of >12 nm. Meanwhile, a large amount of macropores existed in the silica spheres. The bimodal mesopore-marcopore structure resulted in a high protein adsorption capacity (590 mg/g) and a fast adsorption rate (reaching equilibrium within 9 h). ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=22732907 [article] Preparation of monodispersed uniform silica spheres with large pore size for fast adsorption of proteins [texte imprimé] / Zheng Zhai, Auteur ; Yujun Wang, Auteur ; Yangcheng Lu, Auteur . - 2010 . - pp. 4162–4168. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4162–4168 Mots-clés : Adsorption  Pore  size  Preparation Résumé : In this paper, a “temperature-induced gelation” method, combined with microfluidic flows, has been developed to synthesize the uniform silica spheres with large pore structures for the fast adsorption of bovine serum albumin (BSA). The reversible-thermosentive property of methylcellulose (MC) and auxiliary function of poly(ethylene glycol) (PEG) were introduced to realize a fast gelation in a coaxial microfludic device. The effects of temperature and MC concentration on the gelation process were investigated by monitoring the change of viscosity of sol system over time. The silica spheres with different morphologies of internal structure were synthesized by adjusting the concentration of MC. The prepared silica spheres had large pore volumes (>2.0 mL/g) and an average mesopore diameter of >12 nm. Meanwhile, a large amount of macropores existed in the silica spheres. The bimodal mesopore-marcopore structure resulted in a high protein adsorption capacity (590 mg/g) and a fast adsorption rate (reaching equilibrium within 9 h). ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=22732907

Preparation of uniform microcapsules containing 1-octanol for caprolactam extraction / Xingchu Gong in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009) 

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