The comparison of the determination of chemical composition distributions of butadiene-styrene copolymers, obtained by the formula method and experimental method of GPC, is given in this paper. The relative error of a...The comparison of the determination of chemical composition distributions of butadiene-styrene copolymers, obtained by the formula method and experimental method of GPC, is given in this paper. The relative error of average composition was shown to be less than 5%. The formula method was found to be a more convenient and time-saving approach in the characterization of the copolymer composition distribution.展开更多
A convenient way to prepare water soluble or water dispersible conducting polyaniline was developed by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-ion. The conducting pol...A convenient way to prepare water soluble or water dispersible conducting polyaniline was developed by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-ion. The conducting polyaniline possesses electrical conductivity in the range of 10^(-3) to 10^(-2)S/cm depending on the chosen dopant, and it displays an excellent electrochemical redox reversibility in non aqueous systems.展开更多
The cleavage and formation of the di sulfide bond of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) were examined in an aqueous solution of pH value from 0 to 14 with and without polyaniline (PAn), The redox reaction of DMcT...The cleavage and formation of the di sulfide bond of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) were examined in an aqueous solution of pH value from 0 to 14 with and without polyaniline (PAn), The redox reaction of DMcT was accelerated by PAn in acidic condition. The cell using this anodic material was set-up and characterized in aqueous electrolyte.展开更多
The effects of the nature of salts, salt concentration, pH value, degree of hydrolysis as well as surfactant on molecular size of HPAM were studied. It is found that [eta] of HPAM changes with all the above variables,...The effects of the nature of salts, salt concentration, pH value, degree of hydrolysis as well as surfactant on molecular size of HPAM were studied. It is found that [eta] of HPAM changes with all the above variables, and the molecular weight of HPAM can be obtained through [eta] measurement at a specific salts environment in which the [eta] is independent of above factors.展开更多
The properties of the films formed in the electrolyte of PC/DME LiClO4 on two kinds of carbon materials were examined by cathodic polarization measurements. The result suggested that the films on both carbon electrode...The properties of the films formed in the electrolyte of PC/DME LiClO4 on two kinds of carbon materials were examined by cathodic polarization measurements. The result suggested that the films on both carbon electrodes have different morphology which resulted in the different cen performance of the two carbon anodes.展开更多
The preliminary work indicated that passive film is the most important factor influencing cell performance of carbon anode, and the carbon and solvent used govern cell performance by forming the passive film of differ...The preliminary work indicated that passive film is the most important factor influencing cell performance of carbon anode, and the carbon and solvent used govern cell performance by forming the passive film of different properties. A in situ XRD result is also presented.展开更多
The shape memory behavior of a series of PCL/MEI/BDO segmentedpolyurethanes of different composition is presented. The molecular weight of the PCLdids is in the range of 1600-7000. It is found that the shape memory ef...The shape memory behavior of a series of PCL/MEI/BDO segmentedpolyurethanes of different composition is presented. The molecular weight of the PCLdids is in the range of 1600-7000. It is found that the shape memory effect ofsegmented polyurethanes is really related with the crystallinity of the soft segmentregions and the formation of stable hard segment domains as predicted by the modelproposed in our previous papers.展开更多
Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interacti...Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.展开更多
Polyamides containing thieno[2,3-b]thiophene moiety were prepared via a simple polycondensation reaction of the diaminothieno[2,3-b]thiophene monomer la with different kinds of diacid chlorides （including oxalyl, adi...Polyamides containing thieno[2,3-b]thiophene moiety were prepared via a simple polycondensation reaction of the diaminothieno[2,3-b]thiophene monomer la with different kinds of diacid chlorides （including oxalyl, adipoyl, sebacoyl, isophthaloyl, terephthaloyl, 4,4＇-azodibenzoyl, 3,3＇-azodibenzoyl, p-phenylene diacryloyl） in the presence of LiC1 and NMP as a solvent through lowtemperature solution polycondensation. The chemical structures of model compound and synthesized polyamides were confirmed by FTIR, nuclear magnetic resonance spectroscopy （including 1 H-NMR and 13 C-NMR） and elemental analysis. In addition, the thermal stability, crystallinity structure and surface morphology of synthesized polyamides were characterized via thermogravametric analysis （TGA）, wide-angle X-ray diffraction analysis （WAXD） and scanning electron microscopy （SEM）. Also, the corrosion inhibition behavior of selected examples ofpolyamides was investigated; the inhibitive effect of the investigated polymers for carbon steel in 1.0 mol＇L-1 HCI was studied using potentiodynamic polarization （PDP） and electrochemical impedance spectroscopy （EIS） methods. PDP results displayed that the polyamides containing thieno[2,3-b]thiophene moiety can be as mixed-type inhibitors. The inhibition efficiency （P, %） was found to be in the range from 67.13% to 96.01%. There is an increase in P by the synthesized polymers in comparison to the starting monomer. The adsorption of these polymers was found to obey Langmuir adsorption isotherm.展开更多
Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20B_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed...Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20B_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed by Xray diffraction.The patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are amorphous.The Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder substance.Differential scanning calorimetry(DSC) at 300-550℃ was used to evaluate the thermal properties of the Dy_x glass samples.The glass transition temperature T_g(small endothermic peak),start crystallization temperature T_x and crystallization temperature T_c can all be seen on the DSC thermogram(exothermic peaks).The UV-Vis transmittance and absorption spectra were measured.The optical data show that the values of E_d^(ir),E_g^(Ind) and E_U decrease as the amount of Dy_(2)O_(3)increases,indicating a narrowing of the tails due to localized states in the forbidden gap.A concentration quenching event occurs when Dy^(3+) concentrations are above a certain threshold(1%).The addition of Dy_(2)O_(3) increases glass density,while the addition of other Dy(Ⅲ) oxides increases sample density.The radiation shielding values change as a consequence of density fluctuation.The sample with the highest amount of Dy_(2)O_(3)(Dy_(4)) has stronger radiation shielding characteristics;hence,it is superior in terms of shielding outcomes at all energy levels.Such Dy_x samples can be used in various forms of ionizing radiation shielding.展开更多
This research aims to study the impact of yttrium oxide on the radiation protection features of polyvinyl alcohol(PVA) for gamma shielding applications.The yttrium oxide(Y_(2)O_(3)) was instilled through the PVA matri...This research aims to study the impact of yttrium oxide on the radiation protection features of polyvinyl alcohol(PVA) for gamma shielding applications.The yttrium oxide(Y_(2)O_(3)) was instilled through the PVA matrix by different contents(x=0.1 wt%,0,3 wt%,0,7 wt%,0,9 wt%),The morphology of the prepared PVA/Y_(2)O_(3)composites was characterized using scanning electron microscopy(SEM).The samples were investigated using absorption edge,transmittance spectra and dielectric properties.The transmittance and the bandgap energy decrease as the Y2O3content increases while there is an increase in ε’ and ε" as well as the ac conductivity with the content increment of Y_(2)O_(3)till 0.7 wt%.The te mperature dependence of the dc conductivity was measured for all samples in the range of 260-460 K,and it increases with the temperature increasing.To correlate the electrical characteristics of the PVA/Y_(2)O_(3)composites with their structure and evaluate electrical properties with the help of equivalent circuit matching with the experimentally electrical response in the impedance spectrum,the radiation protection properties were also investigated to get the radiation shielding performance of these PVA/Y_(2)O_(3)composite films with varying Y_(2)O(3)content.The linear attenuation coefficient(μ),half value layer(T_(0.5)),and mass attenuation coefficient(μm) were measured.According to all obtained data,PVA/Y_(2)O_(3)composite films with various percentages(0.1 wt%,0.3 wt%,0.7 wt%,0.9 wt%) can be used as a radiation shielding material.展开更多
The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5a-5f using low temperature solution polycondensation technique. The new polymers w...The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5a-5f using low temperature solution polycondensation technique. The new polymers were synthesized by the reaction of thiazole based monomer namely, bis（2-aminothiazol-4-ylbenzylidene）cyclohexanone 3 with different aliphatic and aromatic diacid chlorides using NMP, and in the presence of anhydrous Li Cl as catalyst. Adipoyl, sebacoyl, oxaloyl, terephthaloyl, isophthaloyl dichlorides and biphenyl dicarbonyl dichloride were used as diacid chlorides. The structure of the model compound 4 as well as the new polymers was confirmed by correct elemental and spectral analyses. The thermal properties of those polymers were evaluated by TGA and DTG measurements and correlated to their structural units, beside X-ray diffraction analysis, solubility and viscometry measurements. The inherent viscosities for the synthesized polymers were in the range 0.6–1.03 d L/g. On the other hand the corrosion inhibitive properties of monomer 3 as well as polyamides 5d and 5f as selected examples were carried out on carbon-steel in 0.5 mol/L H2SO4 at 40 °C. The calculated inhibition efficiency（IE%） for polymer 5d was in the range（82 ± 6）% in all selected concentrations. The best value of IE% was obtained at 1 mg/L to reach 98.24% for polymer 5d and at 0.5 mg/L to reach 87.75% for polymer 5f.展开更多
This paper addresses the manipulation of structural,morphology,optical and magnetic properties of LiCo0.25Zn0.25Fe2 O4 ferrite via incorporation of different proportions of La^3+at the expense of iron ions using a sol...This paper addresses the manipulation of structural,morphology,optical and magnetic properties of LiCo0.25Zn0.25Fe2 O4 ferrite via incorporation of different proportions of La^3+at the expense of iron ions using a sol-gel method.The samples were characterized using the X-ray diffraction technique(XRD),Fourier transform infrared(FT-IR)spectroscopy,the energy dispersive X-ray spectra(EDX),inductively coupled plasma optical emission spectroscopy(ICP-OES),high resolution scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET)surface area analysis,ultraviolet-diffuse reflectance spectroscopy(UV-DRS),and vibrating sample magnetometer(VSM)technique.The Rietveld refinements of the samples indicate that at higher concentrations of La^3+,nanostructures with dual phase,i.e.cubic spinel and orthorhombic LaFeO3 perovskite with space group(Pbnm)appear.Optical studies show that the energy band gap(Eg)of the bare LiCo0.25Zn0.25Fe2 O4 ferrite sample(2.18 eV)reaches up to 2.47 eV at x=0.06 and above this concentration,it drops sharply to 2.00 eV.Although the saturation magnetization and the coercivity of LiCo0.25Zn0.25LaxFe2-xO4 are lower than that of LiCo0.25Zn0.25Fe2 O4 NPs.Overall,the superparamagnetic nature and low values of saturation magnetization and coercivity of LiCo0.25Zn0.25LaxFe2-xO4 NPs are suitable to be applied in transformers core.展开更多
The optical properties of substituted fluorenones with diverse structures have been analyzed using molecular orbital calculations in order to understand the structure-property relations. Based on theoretical predictio...The optical properties of substituted fluorenones with diverse structures have been analyzed using molecular orbital calculations in order to understand the structure-property relations. Based on theoretical predictions, synthesis of some model compounds has been attempted. The experimentally obtained optical properties are in close agreement with the theoretically obtained results.展开更多
A new class of unsaturated polyesters based on diethylketone have been prepared by interfacial polymerization of 2,4-bis（4-hydroxybenzylidene）-3-pentanone（I） and 2,4-bis（4-hydroxy-3-methoxybenzylidene）-3-pentan...A new class of unsaturated polyesters based on diethylketone have been prepared by interfacial polymerization of 2,4-bis（4-hydroxybenzylidene）-3-pentanone（I） and 2,4-bis（4-hydroxy-3-methoxybenzylidene）-3-pentanone（II） with 4,4’-azodibenzoyl chloride and 3,3’-azodibenzoyl chloride at ambient temperature. The model compounds were synthesized by reaction of（I） and（II） with benzoyl chloride. The new monomers, model compounds and polyesters have been characterized by different spectral analyses. The polyesters have inherent viscosity of 0.55-0.80 d L/g and moderate number average molecular weight（Mn） in the range of 6150-7400 g/mol. Most of the compounds exhibited their solubility in aprotic solvents while partial solubility in various halogenated organic solvents was observed. The temperatures of 10% weight loss were high（225-330 °C） in nitrogen, indicating that these polyesters have excellent thermal stability. Doping with iodine dramatically raised the conductivity and produced brown colored semiconductive polymers with a maximum conductivity of 2.7 × 10-6 --1cm-1. Moreover, the morphological properties of selected example of polyesters were detected by SEM.展开更多
Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and...Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1H- NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.展开更多
Cyclophosphazene nanotube （PZT） incorporated poly（benzoxazine-co-g-caprolactam） （P（BZ-co-CPL）） nano- composites were developed for improving flame retardant properties. The effects of PZT on the flammability p...Cyclophosphazene nanotube （PZT） incorporated poly（benzoxazine-co-g-caprolactam） （P（BZ-co-CPL）） nano- composites were developed for improving flame retardant properties. The effects of PZT on the flammability properties of P（BZ-co-CPL） matrix were evaluated through UL-94 flammability test and limiting oxygen index （LOI）. The UL-94 results of P（BZ-co-CPL）/PZT hybrid nanocomposites showed V-1 rating, whereas neat P（BZ-co-CPL） showed burning rating. The LOI values are increased from 25.4 to 31.4 for 1.5 wt% PZT incorporated P（BZ-co-CPL） nanocomposite systems. SEM was used to study the char morphology of P（BZ-co-CPL）/PZT after being exposed to UL-94 flammability test. Data from thermal studies indicate that the PZT incorporated P（BZ-co-CPL） systems possess better Tg and thermal degradation behavior when compared to the neat P（BZ-co-CPL）. The values of dielectric constant are decreased with increasing temperature. From the values, it is ascertained that the P（BZ-co-CPL）/PZT systems exhibit stable dielectric behavior with regard to variation in temperature. The TEM images ascertain the uniform dispersion of PZT in the P（BZ-co-CPL） matrix.展开更多
On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-（4-dimethylamino-phenyl）-l-（2,5-dimethyl-thiophen-3-yl）-propenone （D...On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-（4-dimethylamino-phenyl）-l-（2,5-dimethyl-thiophen-3-yl）-propenone （DDTP） has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution （ca. 5×10^-4 mol·L^-1 in DMF） gives a good laser emission in the range 470 --560 nm with emission maximum at 515 nm upon pumping by nitrogen laser （λex=337.1 nm）. The laser parameters such as gain coefficient （a）, emission cross section （Cre） and half life energy （E1/2） at maximum laser emission are also determined.展开更多
文摘The comparison of the determination of chemical composition distributions of butadiene-styrene copolymers, obtained by the formula method and experimental method of GPC, is given in this paper. The relative error of average composition was shown to be less than 5%. The formula method was found to be a more convenient and time-saving approach in the characterization of the copolymer composition distribution.
文摘A convenient way to prepare water soluble or water dispersible conducting polyaniline was developed by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-ion. The conducting polyaniline possesses electrical conductivity in the range of 10^(-3) to 10^(-2)S/cm depending on the chosen dopant, and it displays an excellent electrochemical redox reversibility in non aqueous systems.
文摘The cleavage and formation of the di sulfide bond of 2,5-dimercapto-1,3,4-thiadiazole (DMcT) were examined in an aqueous solution of pH value from 0 to 14 with and without polyaniline (PAn), The redox reaction of DMcT was accelerated by PAn in acidic condition. The cell using this anodic material was set-up and characterized in aqueous electrolyte.
文摘The effects of the nature of salts, salt concentration, pH value, degree of hydrolysis as well as surfactant on molecular size of HPAM were studied. It is found that [eta] of HPAM changes with all the above variables, and the molecular weight of HPAM can be obtained through [eta] measurement at a specific salts environment in which the [eta] is independent of above factors.
文摘The properties of the films formed in the electrolyte of PC/DME LiClO4 on two kinds of carbon materials were examined by cathodic polarization measurements. The result suggested that the films on both carbon electrodes have different morphology which resulted in the different cen performance of the two carbon anodes.
文摘The preliminary work indicated that passive film is the most important factor influencing cell performance of carbon anode, and the carbon and solvent used govern cell performance by forming the passive film of different properties. A in situ XRD result is also presented.
文摘The shape memory behavior of a series of PCL/MEI/BDO segmentedpolyurethanes of different composition is presented. The molecular weight of the PCLdids is in the range of 1600-7000. It is found that the shape memory effect ofsegmented polyurethanes is really related with the crystallinity of the soft segmentregions and the formation of stable hard segment domains as predicted by the modelproposed in our previous papers.
基金the National Natural Science Foundation of China(Nos.21374058,21474060 and 21574078)the Ph.D. Programs Foundation of Ministry of Education of China(No 201331081100166)the Shanghai Rising-Star Program(No.16QA1401800)
文摘Thermoresponsive biotinylated dendronized copolymers carrying dendritic oligoethylene glycol（OEG）pendants were prepared via free radical polymerization,and their protein recognitions based on biotin-avidin interaction investigated.Both first（PG1） and second generation（PG2） dendronized copolymers were designed to examine possible thickness effects on the interaction between biotin and avidin.Inherited from the outstanding thermoresponsive properties from OEG dendrons,these biotinylated cylindrical copolymers show characteristic thermoresponsive behavior which provides an envelope to capture avidin through switching temperatures above or below their phase transition temperatures（T_（cp）s）.Thus,the recognition of polymer-supported biotin with avidin was investigated with UV/vis spectroscopy and dynamic laser light scattering.In contrast to the case for PG1,the increased thickness for copolymer PG2 hinders partially and inhibits the recognition of biotin moieties with avidin either below or above its T_（cp）.This demonstrates the significant architecture effects from dendronized polymers on the biotin moieties to shift onto periphery of the collapsed aggregates,which should be a prerequisite for protein recognition.These kinds of novel thermoresponsive copolymers may pave a way for the interesting biological applications in areas such as reversible activity control of enzyme or proteins,and for controlled delivery of drugs or genes.
文摘Polyamides containing thieno[2,3-b]thiophene moiety were prepared via a simple polycondensation reaction of the diaminothieno[2,3-b]thiophene monomer la with different kinds of diacid chlorides （including oxalyl, adipoyl, sebacoyl, isophthaloyl, terephthaloyl, 4,4＇-azodibenzoyl, 3,3＇-azodibenzoyl, p-phenylene diacryloyl） in the presence of LiC1 and NMP as a solvent through lowtemperature solution polycondensation. The chemical structures of model compound and synthesized polyamides were confirmed by FTIR, nuclear magnetic resonance spectroscopy （including 1 H-NMR and 13 C-NMR） and elemental analysis. In addition, the thermal stability, crystallinity structure and surface morphology of synthesized polyamides were characterized via thermogravametric analysis （TGA）, wide-angle X-ray diffraction analysis （WAXD） and scanning electron microscopy （SEM）. Also, the corrosion inhibition behavior of selected examples ofpolyamides was investigated; the inhibitive effect of the investigated polymers for carbon steel in 1.0 mol＇L-1 HCI was studied using potentiodynamic polarization （PDP） and electrochemical impedance spectroscopy （EIS） methods. PDP results displayed that the polyamides containing thieno[2,3-b]thiophene moiety can be as mixed-type inhibitors. The inhibition efficiency （P, %） was found to be in the range from 67.13% to 96.01%. There is an increase in P by the synthesized polymers in comparison to the starting monomer. The adsorption of these polymers was found to obey Langmuir adsorption isotherm.
文摘Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20B_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed by Xray diffraction.The patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are amorphous.The Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder substance.Differential scanning calorimetry(DSC) at 300-550℃ was used to evaluate the thermal properties of the Dy_x glass samples.The glass transition temperature T_g(small endothermic peak),start crystallization temperature T_x and crystallization temperature T_c can all be seen on the DSC thermogram(exothermic peaks).The UV-Vis transmittance and absorption spectra were measured.The optical data show that the values of E_d^(ir),E_g^(Ind) and E_U decrease as the amount of Dy_(2)O_(3)increases,indicating a narrowing of the tails due to localized states in the forbidden gap.A concentration quenching event occurs when Dy^(3+) concentrations are above a certain threshold(1%).The addition of Dy_(2)O_(3) increases glass density,while the addition of other Dy(Ⅲ) oxides increases sample density.The radiation shielding values change as a consequence of density fluctuation.The sample with the highest amount of Dy_(2)O_(3)(Dy_(4)) has stronger radiation shielding characteristics;hence,it is superior in terms of shielding outcomes at all energy levels.Such Dy_x samples can be used in various forms of ionizing radiation shielding.
基金funded by the Deanship of Scientific Research at Princess Nourah bint Abdulrahman University,through the Research Funding Program (FRP-1443-26)。
文摘This research aims to study the impact of yttrium oxide on the radiation protection features of polyvinyl alcohol(PVA) for gamma shielding applications.The yttrium oxide(Y_(2)O_(3)) was instilled through the PVA matrix by different contents(x=0.1 wt%,0,3 wt%,0,7 wt%,0,9 wt%),The morphology of the prepared PVA/Y_(2)O_(3)composites was characterized using scanning electron microscopy(SEM).The samples were investigated using absorption edge,transmittance spectra and dielectric properties.The transmittance and the bandgap energy decrease as the Y2O3content increases while there is an increase in ε’ and ε" as well as the ac conductivity with the content increment of Y_(2)O_(3)till 0.7 wt%.The te mperature dependence of the dc conductivity was measured for all samples in the range of 260-460 K,and it increases with the temperature increasing.To correlate the electrical characteristics of the PVA/Y_(2)O_(3)composites with their structure and evaluate electrical properties with the help of equivalent circuit matching with the experimentally electrical response in the impedance spectrum,the radiation protection properties were also investigated to get the radiation shielding performance of these PVA/Y_(2)O_(3)composite films with varying Y_(2)O(3)content.The linear attenuation coefficient(μ),half value layer(T_(0.5)),and mass attenuation coefficient(μm) were measured.According to all obtained data,PVA/Y_(2)O_(3)composite films with various percentages(0.1 wt%,0.3 wt%,0.7 wt%,0.9 wt%) can be used as a radiation shielding material.
文摘The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5a-5f using low temperature solution polycondensation technique. The new polymers were synthesized by the reaction of thiazole based monomer namely, bis（2-aminothiazol-4-ylbenzylidene）cyclohexanone 3 with different aliphatic and aromatic diacid chlorides using NMP, and in the presence of anhydrous Li Cl as catalyst. Adipoyl, sebacoyl, oxaloyl, terephthaloyl, isophthaloyl dichlorides and biphenyl dicarbonyl dichloride were used as diacid chlorides. The structure of the model compound 4 as well as the new polymers was confirmed by correct elemental and spectral analyses. The thermal properties of those polymers were evaluated by TGA and DTG measurements and correlated to their structural units, beside X-ray diffraction analysis, solubility and viscometry measurements. The inherent viscosities for the synthesized polymers were in the range 0.6–1.03 d L/g. On the other hand the corrosion inhibitive properties of monomer 3 as well as polyamides 5d and 5f as selected examples were carried out on carbon-steel in 0.5 mol/L H2SO4 at 40 °C. The calculated inhibition efficiency（IE%） for polymer 5d was in the range（82 ± 6）% in all selected concentrations. The best value of IE% was obtained at 1 mg/L to reach 98.24% for polymer 5d and at 0.5 mg/L to reach 87.75% for polymer 5f.
基金the Materials Science Unit,Radiation Physics Department,National Center for Radiation Research and Technology,Egypt,for financing and supporting this study under the project Nanostructured Magnetic Materials。
文摘This paper addresses the manipulation of structural,morphology,optical and magnetic properties of LiCo0.25Zn0.25Fe2 O4 ferrite via incorporation of different proportions of La^3+at the expense of iron ions using a sol-gel method.The samples were characterized using the X-ray diffraction technique(XRD),Fourier transform infrared(FT-IR)spectroscopy,the energy dispersive X-ray spectra(EDX),inductively coupled plasma optical emission spectroscopy(ICP-OES),high resolution scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET)surface area analysis,ultraviolet-diffuse reflectance spectroscopy(UV-DRS),and vibrating sample magnetometer(VSM)technique.The Rietveld refinements of the samples indicate that at higher concentrations of La^3+,nanostructures with dual phase,i.e.cubic spinel and orthorhombic LaFeO3 perovskite with space group(Pbnm)appear.Optical studies show that the energy band gap(Eg)of the bare LiCo0.25Zn0.25Fe2 O4 ferrite sample(2.18 eV)reaches up to 2.47 eV at x=0.06 and above this concentration,it drops sharply to 2.00 eV.Although the saturation magnetization and the coercivity of LiCo0.25Zn0.25LaxFe2-xO4 are lower than that of LiCo0.25Zn0.25Fe2 O4 NPs.Overall,the superparamagnetic nature and low values of saturation magnetization and coercivity of LiCo0.25Zn0.25LaxFe2-xO4 NPs are suitable to be applied in transformers core.
文摘The optical properties of substituted fluorenones with diverse structures have been analyzed using molecular orbital calculations in order to understand the structure-property relations. Based on theoretical predictions, synthesis of some model compounds has been attempted. The experimentally obtained optical properties are in close agreement with the theoretically obtained results.
文摘A new class of unsaturated polyesters based on diethylketone have been prepared by interfacial polymerization of 2,4-bis（4-hydroxybenzylidene）-3-pentanone（I） and 2,4-bis（4-hydroxy-3-methoxybenzylidene）-3-pentanone（II） with 4,4’-azodibenzoyl chloride and 3,3’-azodibenzoyl chloride at ambient temperature. The model compounds were synthesized by reaction of（I） and（II） with benzoyl chloride. The new monomers, model compounds and polyesters have been characterized by different spectral analyses. The polyesters have inherent viscosity of 0.55-0.80 d L/g and moderate number average molecular weight（Mn） in the range of 6150-7400 g/mol. Most of the compounds exhibited their solubility in aprotic solvents while partial solubility in various halogenated organic solvents was observed. The temperatures of 10% weight loss were high（225-330 °C） in nitrogen, indicating that these polyesters have excellent thermal stability. Doping with iodine dramatically raised the conductivity and produced brown colored semiconductive polymers with a maximum conductivity of 2.7 × 10-6 --1cm-1. Moreover, the morphological properties of selected example of polyesters were detected by SEM.
文摘Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone （I）, dithiophenylidenecyclohexanone （II） and dithiophenylideneacetone （III） with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1H- NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40-0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185℃ to 280℃ in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.
基金financially supported by the BRNS,G.No.2012/37C/9/BRNS,Mumbai,Govt.of India
文摘Cyclophosphazene nanotube （PZT） incorporated poly（benzoxazine-co-g-caprolactam） （P（BZ-co-CPL）） nano- composites were developed for improving flame retardant properties. The effects of PZT on the flammability properties of P（BZ-co-CPL） matrix were evaluated through UL-94 flammability test and limiting oxygen index （LOI）. The UL-94 results of P（BZ-co-CPL）/PZT hybrid nanocomposites showed V-1 rating, whereas neat P（BZ-co-CPL） showed burning rating. The LOI values are increased from 25.4 to 31.4 for 1.5 wt% PZT incorporated P（BZ-co-CPL） nanocomposite systems. SEM was used to study the char morphology of P（BZ-co-CPL）/PZT after being exposed to UL-94 flammability test. Data from thermal studies indicate that the PZT incorporated P（BZ-co-CPL） systems possess better Tg and thermal degradation behavior when compared to the neat P（BZ-co-CPL）. The values of dielectric constant are decreased with increasing temperature. From the values, it is ascertained that the P（BZ-co-CPL）/PZT systems exhibit stable dielectric behavior with regard to variation in temperature. The TEM images ascertain the uniform dispersion of PZT in the P（BZ-co-CPL） matrix.
文摘On the line of a previous work on the spectral properties of some of heteroaryl chalcone, the effect of medium acidity and photoreactivity of 3-（4-dimethylamino-phenyl）-l-（2,5-dimethyl-thiophen-3-yl）-propenone （DDTP） has been investigated in dimethylformamide and in chloromethane solvents such as methylenechloride, chloroform and carbon tetrachloride. The dye solution （ca. 5×10^-4 mol·L^-1 in DMF） gives a good laser emission in the range 470 --560 nm with emission maximum at 515 nm upon pumping by nitrogen laser （λex=337.1 nm）. The laser parameters such as gain coefficient （a）, emission cross section （Cre） and half life energy （E1/2） at maximum laser emission are also determined.
