The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex fo...The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex form, such as fan-like aggregates consisting of rod-like BaC 2O 4·H 2O crystals and spherical aggregates consisting of flake-like BaC 2O 4·3.5H 2O crystals were readily produced in aqueous solutions of PEG-b-PMMA. This result may provide an effective method for controlling the morphology and polymorph of inorganic crystals.展开更多
BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (I...BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (IPNs). The tetra gonal nanocrystalline BaTiO3 was obtained by hydrothermal process and calcinatio n at 1 200 ℃. The prepared materials were polarized with high voltage a nd small current, and protected by silicon oil. The morphology of BaTiO3/ IPNs and the effect of combination of BaTiO3 on the damping behavior of IPNs were stu died. The relationship between damping performance and dielectric charater was a lso discussed in terms of dielectric constant and dielectric loss measured. The results show that the areas under loss modulus (E″) and the values of loss fact ors (tanBaTiO3 into IPNs system. The m aximum value of E″ increased above 100 MPa compared with pure IPNs and the exte nt increased more remarkably after polarizing process. The main and shoulder pea k of tand the temperatu re ranges of tan℃. Moreover, through polarizing proc ess, the composites exhibited synergistic action caused by elastomeric damping, interfacial abrasive damping and piezoelectric damping mechanisms. The relations hip study of damping property and dielectric characters showed that the temperat ure ranges exhibited excellent consistency of maximum dielectric loss and modulu s with damping loss factor.展开更多
The effect of preparation method on the properties of alumina modified by La2O3 and BaO was investigated by means of Low temperature nitrogen adsorption-desorption, NH3-TPD, NO-TPD and XRD. The results show that alumi...The effect of preparation method on the properties of alumina modified by La2O3 and BaO was investigated by means of Low temperature nitrogen adsorption-desorption, NH3-TPD, NO-TPD and XRD. The results show that alumina prepared by peptizing method exhibits the best textural properties, alumina obtained by co-precipitation method presents the strongest surface acidity and alumina derived from impregnation method shows the best ability of NO adsorption. After calcination at 1 100 ℃, all alumina except that from impregnation method have excellent thermal stability. When the specific surface area and pore volume of alumina are large enough, the activity of catalyst Pd/alumina is affected primarily by the surface acidity of alumina.展开更多
A molecular bowl with barium ion covering one portal of decamethylcucurbit[5]uril as a‘metal-ion- bottom’has been synthesized. The structure of the molecular bowl has been confirmed by the single crystal X-ray diffr...A molecular bowl with barium ion covering one portal of decamethylcucurbit[5]uril as a‘metal-ion- bottom’has been synthesized. The structure of the molecular bowl has been confirmed by the single crystal X-ray diffraction determination. It belongs to orthorhombic with space group of Pna21. The crystal unit cell parameters are: a=3.2108(6) nm, b=1.4742(3) nm, c=1.1516(2) nm, and V=5.4509(18) nm3, Dc=1.677 Mg·m-3, Z=4, F(000)= 2832, R=0.0551, wR=0.1568. CCDC: 290552.展开更多
文摘The crystallization of barium oxalate in the presence of a double-hydrophilic block copolymer poly(ethylene glycol)-block-poly(methacrylic acid) (PEG-b-PMAA) was investigated. Barium oxalate crystals with a complex form, such as fan-like aggregates consisting of rod-like BaC 2O 4·H 2O crystals and spherical aggregates consisting of flake-like BaC 2O 4·3.5H 2O crystals were readily produced in aqueous solutions of PEG-b-PMMA. This result may provide an effective method for controlling the morphology and polymorph of inorganic crystals.
文摘BaTiO3/ Interpenetrating Polymer Networks (IPNs) composites were prepared by combination of BaTiO3 nanocrystal in tetragonal system and polyurethane(PU)/ unsaturated polyester (UP) interpenetrating polymer networks (IPNs). The tetra gonal nanocrystalline BaTiO3 was obtained by hydrothermal process and calcinatio n at 1 200 ℃. The prepared materials were polarized with high voltage a nd small current, and protected by silicon oil. The morphology of BaTiO3/ IPNs and the effect of combination of BaTiO3 on the damping behavior of IPNs were stu died. The relationship between damping performance and dielectric charater was a lso discussed in terms of dielectric constant and dielectric loss measured. The results show that the areas under loss modulus (E″) and the values of loss fact ors (tanBaTiO3 into IPNs system. The m aximum value of E″ increased above 100 MPa compared with pure IPNs and the exte nt increased more remarkably after polarizing process. The main and shoulder pea k of tand the temperatu re ranges of tan℃. Moreover, through polarizing proc ess, the composites exhibited synergistic action caused by elastomeric damping, interfacial abrasive damping and piezoelectric damping mechanisms. The relations hip study of damping property and dielectric characters showed that the temperat ure ranges exhibited excellent consistency of maximum dielectric loss and modulu s with damping loss factor.
文摘The effect of preparation method on the properties of alumina modified by La2O3 and BaO was investigated by means of Low temperature nitrogen adsorption-desorption, NH3-TPD, NO-TPD and XRD. The results show that alumina prepared by peptizing method exhibits the best textural properties, alumina obtained by co-precipitation method presents the strongest surface acidity and alumina derived from impregnation method shows the best ability of NO adsorption. After calcination at 1 100 ℃, all alumina except that from impregnation method have excellent thermal stability. When the specific surface area and pore volume of alumina are large enough, the activity of catalyst Pd/alumina is affected primarily by the surface acidity of alumina.
文摘A molecular bowl with barium ion covering one portal of decamethylcucurbit[5]uril as a‘metal-ion- bottom’has been synthesized. The structure of the molecular bowl has been confirmed by the single crystal X-ray diffraction determination. It belongs to orthorhombic with space group of Pna21. The crystal unit cell parameters are: a=3.2108(6) nm, b=1.4742(3) nm, c=1.1516(2) nm, and V=5.4509(18) nm3, Dc=1.677 Mg·m-3, Z=4, F(000)= 2832, R=0.0551, wR=0.1568. CCDC: 290552.
