Four oil absorbents based on styrene butadiene (SBR), i.e., pure SBR (PS), 4. tert-butylstyrene-SBR (PBS), EPDM-SBR network (PES) and 4.tert-butylstyrene-EPDMSBR (PBES), were produced from crosslinking polymerization ...Four oil absorbents based on styrene butadiene (SBR), i.e., pure SBR (PS), 4. tert-butylstyrene-SBR (PBS), EPDM-SBR network (PES) and 4.tert-butylstyrene-EPDMSBR (PBES), were produced from crosslinking polymerization of uncured styrene butadiene rubber (SBR), 4-tert-butylstyrene (tBS) and ethylene-propylenc-diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a pre-polymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with the method ASTM (F726-81). The order of maximum oil absorbency was PBES>PBS>PES>PS. The maximum values of oil absorbency of PBES and PBS were 74.0g/g and 69.5g/g, respectively. Gel fractions and swelling kinetic constants, however, had the opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49. 97×10^(-2)h^(-1).展开更多
The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg)...The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg). In naphthenic oil which is a good solvent for the butadiene blocks, but a non-solvent for the styrene blocks and PPE, PPE was selectively included into styrene blocks in SBS, and induced the increase of the Tg of these blocks. The melting temperature determined by viscoelastic measurements and softening temperature of the gels were elevated by adding PPE, while no significant change was detected by adding polystyrene. The gel became opaque by adding PPE, and partially separated phases were observed by field emission scanning electron microscopy (FE-SEM). The dependence of the viscoelastic behavior on the PPE concentration can be explained by the structural change observed by FE-SEM.展开更多
Solvent exchange induced in situ forming gel(ISG) is the promising drug delivery system for periodontitis treatment owing to the prospect of maintaining an effective high drug level in the gingival crevicular fluid. I...Solvent exchange induced in situ forming gel(ISG) is the promising drug delivery system for periodontitis treatment owing to the prospect of maintaining an effective high drug level in the gingival crevicular fluid. In the present study, the influence of clove oil(CO) on the characteristics of doxycycline hyclate(DH)-loaded ISG comprising Eudragit RS(ERS) was investigated including viscosity/rheology, syringeability, in vitro gel formation/drug release, matrix formation/solvent diffusion and antimicrobial activities. CO could dissolve ERS and increase the viscosity of ISG and its hydrophobicity could also retard the diffusion of solvent and hinder the drug diffusion; thus, the minimization of burst effect and sustained drug release were achieved effectively. All the prepared ISGs comprising CO could expel through the 27-gauge needle for administration by injection and transform into matrix depot after exposure to the simulated gingival crevicular fluid. The antimicrobial activities against Staphylococcus aureus, Escherichia coli, Streptococcus mutans and Porphyromonas gingivalis were increased when the ratio of CO and N-methyl pyrrolidone(NMP) was decreased from 1:1 to 1:10 owing to higher diffusion of DH except that for C. albicans was increased as CO amount was higher.Therefore, CO could minimize the burst while prolonging the drug release of DH-loaded ERS ISG for use as a local drug delivery system for periodontitis treatment.展开更多
Olive oil doped Nanosilica is successfully prepared by wet chemical synthesis method. Samples were analyzed by a variety of techniques, including X-ray diffraction, FTIR, absorption and emission spectrometers to repor...Olive oil doped Nanosilica is successfully prepared by wet chemical synthesis method. Samples were analyzed by a variety of techniques, including X-ray diffraction, FTIR, absorption and emission spectrometers to report the capability of Sol-Gel technology on preparing of silica monolith as a host material for Olive oil, and investigate the effect of converting Olive oil to a solid state on its optical properties. Some absorption bands of Olive oil are disappearing from absorption spectrum of doped silica. Only single strong fluorescence peak was appearing in fluorescence spectrum of pure Olive oil at wavelength around 678 nm which attributed to chlorophylls, while fluorescence spectrum to doped sample shows two strong fluorescence peaks at the wavelength 681 nm and 585 nm which attributed to chlorophylls and Vitamin E respectively. The doping process enhances fluorescence activity of Olive oil through enhancing intensity of the fluorescence peak corresponding to Vitamin E. Absorption and fluorescence spectrums to doped silica sample give a good indication in direction of using Sol-Gel technique to prepare?for Olive oil doped SiO2 as an optical active material.展开更多
A composite gel was prepared for plugging CO2 channeling, which is a serious problem for enhanced oil recovery with CO2. A composite gel which is one of the materials for successful control of CO2 channeling during CO...A composite gel was prepared for plugging CO2 channeling, which is a serious problem for enhanced oil recovery with CO2. A composite gel which is one of the materials for successful control of CO2 channeling during CO2 injection process was studied in this paper. SEM and nano particle size analysis were used to describe this material’s microstructure. Its effect on CO2 channeling control was evaluated with core flow experiments. Both the rheological test and core plugging experiments indicated that both acrylamide monomer concentration and reaction pressure had positive influences on gel properties. The gel system with an acrylamide monomer concentration of 2% and 5% sodium silicate was proved to have excellent strength, elastic and plugging efficiency, which confirmed huge development potential and wide application of the composite gel system. The high-pressure acid environment arising from the CO2 injection not only reacts with solid silicate to form silicic acid gel, but also facilitates efficient polymerization.展开更多
Different La2O3 contents（0, 1, 2, 3, and 5 wt%） were used to prepared La2O3-ZrO2 mixed oxides calcined at 600 ℃ by the sol-gel method. The catalytic activity was measured as biodiesel production from canola oil thr...Different La2O3 contents（0, 1, 2, 3, and 5 wt%） were used to prepared La2O3-ZrO2 mixed oxides calcined at 600 ℃ by the sol-gel method. The catalytic activity was measured as biodiesel production from canola oil through a transesterification reaction. The characterization results indicate that the La2O3 monolayer formation and extent of basicity of m-ZrO2 have a large influence on biodiesel production.Greater biodiesel conversion（56% at 4 h） was obtained with the 3% La2O3-ZrO2 catalyst in the presence of basic sites and the formation of a monolayer of La2O3. The decrease in the catalytic activity for 5% La2O3-ZrO2 resulted from the loss of active sites on the catalyst because of agglomeration, which was suggested by XPS and the isoelectric point. The kinetic data fit to a pseudo-first order constant, and the largest kinetic constant corresponds to 3% La2O3-ZrO2, currently the largest heterogeneous non-alkaline metal catalyst reported for a transesterification reaction.展开更多
Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system ...Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.展开更多
文摘Four oil absorbents based on styrene butadiene (SBR), i.e., pure SBR (PS), 4. tert-butylstyrene-SBR (PBS), EPDM-SBR network (PES) and 4.tert-butylstyrene-EPDMSBR (PBES), were produced from crosslinking polymerization of uncured styrene butadiene rubber (SBR), 4-tert-butylstyrene (tBS) and ethylene-propylenc-diene terpolymer (EPDM). The reaction took place in toluene using benzoyl peroxide (BPO) as an initiator. Uncured SBR was used as both a pre-polymer and a crosslink agent in this work, and the crosslinked polymer was identified by IR spectroscopy. The oil absorbency of the crosslinked polymer was evaluated with the method ASTM (F726-81). The order of maximum oil absorbency was PBES>PBS>PES>PS. The maximum values of oil absorbency of PBES and PBS were 74.0g/g and 69.5g/g, respectively. Gel fractions and swelling kinetic constants, however, had the opposite sequences. The swelling kinetic constant of PS evaluated by an experimental equation was 49. 97×10^(-2)h^(-1).
文摘The thermal stability of oil gels formed by styrene-butadiene-styrene triblock copolymer (SBS) was improved by adding a small amount of poly(phenylene ether) (PPE), which has a higher glass transition temperature (Tg). In naphthenic oil which is a good solvent for the butadiene blocks, but a non-solvent for the styrene blocks and PPE, PPE was selectively included into styrene blocks in SBS, and induced the increase of the Tg of these blocks. The melting temperature determined by viscoelastic measurements and softening temperature of the gels were elevated by adding PPE, while no significant change was detected by adding polystyrene. The gel became opaque by adding PPE, and partially separated phases were observed by field emission scanning electron microscopy (FE-SEM). The dependence of the viscoelastic behavior on the PPE concentration can be explained by the structural change observed by FE-SEM.
基金the Research and Development Institute, Silpakorn University (Grant No. SURDI 58/01/38)facilitated by the Faculty of Pharmacy, Silpakorn University, Thailand
文摘Solvent exchange induced in situ forming gel(ISG) is the promising drug delivery system for periodontitis treatment owing to the prospect of maintaining an effective high drug level in the gingival crevicular fluid. In the present study, the influence of clove oil(CO) on the characteristics of doxycycline hyclate(DH)-loaded ISG comprising Eudragit RS(ERS) was investigated including viscosity/rheology, syringeability, in vitro gel formation/drug release, matrix formation/solvent diffusion and antimicrobial activities. CO could dissolve ERS and increase the viscosity of ISG and its hydrophobicity could also retard the diffusion of solvent and hinder the drug diffusion; thus, the minimization of burst effect and sustained drug release were achieved effectively. All the prepared ISGs comprising CO could expel through the 27-gauge needle for administration by injection and transform into matrix depot after exposure to the simulated gingival crevicular fluid. The antimicrobial activities against Staphylococcus aureus, Escherichia coli, Streptococcus mutans and Porphyromonas gingivalis were increased when the ratio of CO and N-methyl pyrrolidone(NMP) was decreased from 1:1 to 1:10 owing to higher diffusion of DH except that for C. albicans was increased as CO amount was higher.Therefore, CO could minimize the burst while prolonging the drug release of DH-loaded ERS ISG for use as a local drug delivery system for periodontitis treatment.
文摘Olive oil doped Nanosilica is successfully prepared by wet chemical synthesis method. Samples were analyzed by a variety of techniques, including X-ray diffraction, FTIR, absorption and emission spectrometers to report the capability of Sol-Gel technology on preparing of silica monolith as a host material for Olive oil, and investigate the effect of converting Olive oil to a solid state on its optical properties. Some absorption bands of Olive oil are disappearing from absorption spectrum of doped silica. Only single strong fluorescence peak was appearing in fluorescence spectrum of pure Olive oil at wavelength around 678 nm which attributed to chlorophylls, while fluorescence spectrum to doped sample shows two strong fluorescence peaks at the wavelength 681 nm and 585 nm which attributed to chlorophylls and Vitamin E respectively. The doping process enhances fluorescence activity of Olive oil through enhancing intensity of the fluorescence peak corresponding to Vitamin E. Absorption and fluorescence spectrums to doped silica sample give a good indication in direction of using Sol-Gel technique to prepare?for Olive oil doped SiO2 as an optical active material.
文摘A composite gel was prepared for plugging CO2 channeling, which is a serious problem for enhanced oil recovery with CO2. A composite gel which is one of the materials for successful control of CO2 channeling during CO2 injection process was studied in this paper. SEM and nano particle size analysis were used to describe this material’s microstructure. Its effect on CO2 channeling control was evaluated with core flow experiments. Both the rheological test and core plugging experiments indicated that both acrylamide monomer concentration and reaction pressure had positive influences on gel properties. The gel system with an acrylamide monomer concentration of 2% and 5% sodium silicate was proved to have excellent strength, elastic and plugging efficiency, which confirmed huge development potential and wide application of the composite gel system. The high-pressure acid environment arising from the CO2 injection not only reacts with solid silicate to form silicic acid gel, but also facilitates efficient polymerization.
基金financial support CONICYT, Fondecyt Grants 3150010 and 1170083
文摘Different La2O3 contents（0, 1, 2, 3, and 5 wt%） were used to prepared La2O3-ZrO2 mixed oxides calcined at 600 ℃ by the sol-gel method. The catalytic activity was measured as biodiesel production from canola oil through a transesterification reaction. The characterization results indicate that the La2O3 monolayer formation and extent of basicity of m-ZrO2 have a large influence on biodiesel production.Greater biodiesel conversion（56% at 4 h） was obtained with the 3% La2O3-ZrO2 catalyst in the presence of basic sites and the formation of a monolayer of La2O3. The decrease in the catalytic activity for 5% La2O3-ZrO2 resulted from the loss of active sites on the catalyst because of agglomeration, which was suggested by XPS and the isoelectric point. The kinetic data fit to a pseudo-first order constant, and the largest kinetic constant corresponds to 3% La2O3-ZrO2, currently the largest heterogeneous non-alkaline metal catalyst reported for a transesterification reaction.
基金Supported by the Basic Research Funds Reserved to State-run Universities(18CX02171A,18CX02033A)
文摘Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.
