Spherical monodispersed and submicron-sized Y203 powders were successfully synthesized through the urea homogeneous precipitation method adding PVA, PVP, or PVA and PVP compound （PVA/PVP） as the dispersant which gen...Spherical monodispersed and submicron-sized Y203 powders were successfully synthesized through the urea homogeneous precipitation method adding PVA, PVP, or PVA and PVP compound （PVA/PVP） as the dispersant which generated no impurity phases after calcining. The productivity is up to 60% at 107 ±2 ℃ for 3.5 h in an oil bath. The structure, phase composition and evolution, morphology and specific surface area of Y203 precursor and the calcined powders were explored by means of XRD, TG/DTA, FTIR, SEM, TEM and Micropore analyzer （BET）. The spherical particle size of the powders calcined at 900 ℃ for 2 h was 330-350 nm. In this study, 15.5 Wt.% PVA, 8.5 Wt.% PVP or the mixture of both is in favor of enhancing the dispersity of the products. Based on what we have already achieved, it is rather sinificant to advance this research.展开更多
The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallin...The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallinity,T_m and T_c of PVA were obviously lower thanthose of pure PVA; the crystal growth changed from three dimensional to two dimensional andonly a single T_g was detected. These facts demonstrated that this crystalline and amorphousblend have good miscibility. TG curves showed that providing the quantity of K_2S_2O_8 added ismore than 3 wt%,in the blends PVA will form a stable CL-network, whose thermal degradationtemperature was near to that of PVP. But crosslinking reaction will not take place for PVP. Theprocesses of thermal degradation of CL-blends are based on combining both the thermaldegradation of PVP and that of PVA crosslinked with corresponding quantity of K_2S_2O_8 CL-agent, respectively. The UV measurements showed that 75 wt% of PVP may be remained in CL-blend hydrogelscrosslinked by adding (3--5 wt% )K_2S_2O_8. This is mainly due to the stable CL-network formed and the good compatibility and properentanglement between the composites in the CL-blends.展开更多
Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with differen...Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with different surfactants like poly vinyl pyrrolidone (PVP), poly vinyl alcohol (PVA) and poly oxyethylene lauryl ether (POLE). It was found that shape and size of Ir-nano particles resulted were related to kind of capping agent (surfactant) used. The characterization of the synthesized nano particle has been carried out by UV-vis, X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM) and transmission electron microscopic (TEM) techniques. UV-vis and FT-IR confirm the oxidation of IrCl3 into IrO2 while XRD confirms the amorphous nature of the iridium nanoparticles synthesized. The morphology and size of the particle were confirmed by TEM. The average particle size determined by Scherrer equation was about 4.12 nm to 4.23 nm with PVP, 2.74 to 3.36 nm with PVA and 20.41 to 42.25 nm with POLE. Poly oxyethylene lauryl ether particles were not further analyzed because of their large size and less stability. Further particle size was confirmed with TEM, which was 4.5 nm with PVP and 7.0 nm with PVA. The particles are spherical with no agglomeration tendency.展开更多
In this paper, transparent poly(vinyl alcohol)/poly(vinyl pyrrolidone)(PVA/PVP) hydrogels were prepared by using the solvent of dimethyl sulfoxide(DMSO) aqueous solution and the method of freeze/thawing. The effect of...In this paper, transparent poly(vinyl alcohol)/poly(vinyl pyrrolidone)(PVA/PVP) hydrogels were prepared by using the solvent of dimethyl sulfoxide(DMSO) aqueous solution and the method of freeze/thawing. The effect of PVP interaction, mechanical property and transparence of PVA/PVP hydrogel was investigated and evaluated by FT-IR analysis, mechanical test machine and UV spectrophotometer. The results showed that when the content of PVP was 8% in the DMSO aqueous solution, the highest transparence of PVA/PVP hydrogel was obtained, with excellent tensile strength values higher than 3.5 MPa. Therefore, the PVA/PVP hydrogel composite has a potential to be used as the transparent core of a novel artificial cornea.展开更多
基金supported by the National Natural Science Foundation of China(91022035)the Center for Advanced Materials,Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences
文摘Spherical monodispersed and submicron-sized Y203 powders were successfully synthesized through the urea homogeneous precipitation method adding PVA, PVP, or PVA and PVP compound （PVA/PVP） as the dispersant which generated no impurity phases after calcining. The productivity is up to 60% at 107 ±2 ℃ for 3.5 h in an oil bath. The structure, phase composition and evolution, morphology and specific surface area of Y203 precursor and the calcined powders were explored by means of XRD, TG/DTA, FTIR, SEM, TEM and Micropore analyzer （BET）. The spherical particle size of the powders calcined at 900 ℃ for 2 h was 330-350 nm. In this study, 15.5 Wt.% PVA, 8.5 Wt.% PVP or the mixture of both is in favor of enhancing the dispersity of the products. Based on what we have already achieved, it is rather sinificant to advance this research.
文摘The thermal behavior, miscibility, crystallite conformation and thermal stability ofcrosslinked(CL-) PVA/PVP blends were studied by DSC and TG methods, respectively. DSCresults showed that in the blend, the crystallinity,T_m and T_c of PVA were obviously lower thanthose of pure PVA; the crystal growth changed from three dimensional to two dimensional andonly a single T_g was detected. These facts demonstrated that this crystalline and amorphousblend have good miscibility. TG curves showed that providing the quantity of K_2S_2O_8 added ismore than 3 wt%,in the blends PVA will form a stable CL-network, whose thermal degradationtemperature was near to that of PVP. But crosslinking reaction will not take place for PVP. Theprocesses of thermal degradation of CL-blends are based on combining both the thermaldegradation of PVP and that of PVA crosslinked with corresponding quantity of K_2S_2O_8 CL-agent, respectively. The UV measurements showed that 75 wt% of PVP may be remained in CL-blend hydrogelscrosslinked by adding (3--5 wt% )K_2S_2O_8. This is mainly due to the stable CL-network formed and the good compatibility and properentanglement between the composites in the CL-blends.
文摘Commonly transition metal nano particle are synthesized by physical, chemical or electrochemical methods. In the present work colloidal iridium nanoparticles were synthesized by chemical oxidation method with different surfactants like poly vinyl pyrrolidone (PVP), poly vinyl alcohol (PVA) and poly oxyethylene lauryl ether (POLE). It was found that shape and size of Ir-nano particles resulted were related to kind of capping agent (surfactant) used. The characterization of the synthesized nano particle has been carried out by UV-vis, X-ray diffraction (XRD), FT-IR, scanning electron microscopy (SEM) and transmission electron microscopic (TEM) techniques. UV-vis and FT-IR confirm the oxidation of IrCl3 into IrO2 while XRD confirms the amorphous nature of the iridium nanoparticles synthesized. The morphology and size of the particle were confirmed by TEM. The average particle size determined by Scherrer equation was about 4.12 nm to 4.23 nm with PVP, 2.74 to 3.36 nm with PVA and 20.41 to 42.25 nm with POLE. Poly oxyethylene lauryl ether particles were not further analyzed because of their large size and less stability. Further particle size was confirmed with TEM, which was 4.5 nm with PVP and 7.0 nm with PVA. The particles are spherical with no agglomeration tendency.
基金National Natural Science Foundation of Chinagrant number:11002016,30900306,81171473 and 11032012
文摘In this paper, transparent poly(vinyl alcohol)/poly(vinyl pyrrolidone)(PVA/PVP) hydrogels were prepared by using the solvent of dimethyl sulfoxide(DMSO) aqueous solution and the method of freeze/thawing. The effect of PVP interaction, mechanical property and transparence of PVA/PVP hydrogel was investigated and evaluated by FT-IR analysis, mechanical test machine and UV spectrophotometer. The results showed that when the content of PVP was 8% in the DMSO aqueous solution, the highest transparence of PVA/PVP hydrogel was obtained, with excellent tensile strength values higher than 3.5 MPa. Therefore, the PVA/PVP hydrogel composite has a potential to be used as the transparent core of a novel artificial cornea.
