A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material charac...A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m2/g and 0.308 4 cm3/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance.展开更多
In this paper,a new method combines chemical/physical crosslinking,and emulsification-foaming porogenic was adopted to prepare n-hydroxyapatite(n-HA)/polyvinyl alcohol(PVA)/chitosan(CS)porous composite hydrogel using ...In this paper,a new method combines chemical/physical crosslinking,and emulsification-foaming porogenic was adopted to prepare n-hydroxyapatite(n-HA)/polyvinyl alcohol(PVA)/chitosan(CS)porous composite hydrogel using artificial cornea scaffold materials.The fabricate conditions,including the type and amount of emulsification-foaming porogen,mixing time and speed etc.were researched.The results showed the optimal condition that the alkylphenol polyoxyethylene ether(OP)acted as emulsification-foaming porogen,with the ratio of WPVA/WOP as 3.75,and mixing 15 min with a stirring speed of 800 r·min-1.Additionally,the fabricated composite hydrogel scaffold materials possessed interconnected internal holes,a moisture content of above 65%,and tensile strength of above 6 MPa.In vitro cytotoxicity and acute systemic toxicity assay confirmed that the scaffolds did not show any cytotoxicity.The as-prepared hydrogel could be a promising candidate for artificial cornea scaffold material.展开更多
The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite(HA)and beta tri-calcium phosphate(β-TCP).Prior to fo...The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite(HA)and beta tri-calcium phosphate(β-TCP).Prior to formulating the paste,HA andβ-TCP were calcined at 800℃and 975℃(11 h),milled,and blended into 15%/85%HA/β-TCP volume-mixed paste.Fabricated cylindrical rods were subsequently sintered to 900℃,1100℃or 1250℃.The sintered specimens were characterized by helium pycnometry,X-ray diffraction(XRD),Fourier transform-infrared(FT-IR),and inductively coupled plasma(ICP)spectroscopy for evaluation of porosity,crystalline phase,functional-groups,and Ca:P ratio,respectively.Mechanical properties were assessed via 3-point bending and diametral compression.Qualitative microstructural evaluation using scanning electron microscopy(SEM)showed larger pores and a broader pore size distribution(PSD)for materials sintered at 900℃and 1100℃,whereas the 1250℃samples showed more uniform PSD.Porosity quantification showed significantly higher porosity for materials sintered to 900℃and 1250℃(p<0.05).XRD indicated substantial deviations from the 15%/85%HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased.Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes(p<0.05).Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering.展开更多
基金Project(2007BAE12B01) supported by the National Key Technology Research and Development Program of China
文摘A process was proposed based on the combination of chemical and physical activation for the production of activated carbons used as the electrode material for electric double layer capacitor (EDLC). By material characterization and electrochemical methods, the influences of the activitation process on the specific surface area, pore structure and electrochemical properties of the activated carbons were investigated. The results show that specific surface area, the mesopore volume, and the specific capacitance increase with the increase of the mass ratio of KOH to char (m(KOH)/m(char)) and the activation time, respectively. When m(KOH)/m(char) is 4.0, the specific surface area and the mesopore volume reach the maximum values, i.e. 1 960 m2/g and 0.308 4 cm3/g, and the specific capacitance is 120.7 F/g synchronously. Compared with the chemical activation, the activated carbons prepared by chemical-physical activation show a larger mesopore volume, a higher ratio of mesopore and a larger specific capacitance.
基金Supported by the Key Technology R&D Program of Shenzhen Municipal(JSGG20120614164013545)Basic Research Program of Shenzhen Municipal(JCYJ20130329102614715).
文摘In this paper,a new method combines chemical/physical crosslinking,and emulsification-foaming porogenic was adopted to prepare n-hydroxyapatite(n-HA)/polyvinyl alcohol(PVA)/chitosan(CS)porous composite hydrogel using artificial cornea scaffold materials.The fabricate conditions,including the type and amount of emulsification-foaming porogen,mixing time and speed etc.were researched.The results showed the optimal condition that the alkylphenol polyoxyethylene ether(OP)acted as emulsification-foaming porogen,with the ratio of WPVA/WOP as 3.75,and mixing 15 min with a stirring speed of 800 r·min-1.Additionally,the fabricated composite hydrogel scaffold materials possessed interconnected internal holes,a moisture content of above 65%,and tensile strength of above 6 MPa.In vitro cytotoxicity and acute systemic toxicity assay confirmed that the scaffolds did not show any cytotoxicity.The as-prepared hydrogel could be a promising candidate for artificial cornea scaffold material.
文摘The objective of this study was to characterize the chemical and physical properties of bioactive ceramics prepared from an aqueous paste containing hydroxyapatite(HA)and beta tri-calcium phosphate(β-TCP).Prior to formulating the paste,HA andβ-TCP were calcined at 800℃and 975℃(11 h),milled,and blended into 15%/85%HA/β-TCP volume-mixed paste.Fabricated cylindrical rods were subsequently sintered to 900℃,1100℃or 1250℃.The sintered specimens were characterized by helium pycnometry,X-ray diffraction(XRD),Fourier transform-infrared(FT-IR),and inductively coupled plasma(ICP)spectroscopy for evaluation of porosity,crystalline phase,functional-groups,and Ca:P ratio,respectively.Mechanical properties were assessed via 3-point bending and diametral compression.Qualitative microstructural evaluation using scanning electron microscopy(SEM)showed larger pores and a broader pore size distribution(PSD)for materials sintered at 900℃and 1100℃,whereas the 1250℃samples showed more uniform PSD.Porosity quantification showed significantly higher porosity for materials sintered to 900℃and 1250℃(p<0.05).XRD indicated substantial deviations from the 15%/85%HA/β-TCP formulation following sintering where lower amounts of HA were observed when sintering temperature was increased.Mechanical testing demonstrated significant differences between calcination temperatures and different sintering regimes(p<0.05).Variation in chemical composition and mechanical properties of bioactive ceramics were direct consequences of calcination and sintering.
