检索结果-南通市图书馆

Ambient Temperature Living Radical Copolymerization of Styrene and Methyl Methacrylate with sodium hypophosphite as Reducing Agent

引用

Chinese Journal of Polymer Science 2015年第2期33卷 362-370页

作者：刘晓辉 Hui-na Li Fei-jun Zhang Shan Xie Zhan-jun Liu 李彦国 School of Materials Science and Engineering Tianjin Key Laboratory of Fiber Modification and Functional FiberTianjin Polytechnic University College of Pharmacy Hebei United University State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences

A facile, safe and economical reducing agent, sodium hypophosphite（Na H2PO2·H2O）, has been successfully employed for ambient temperature living radical copolymerization of styrene（St） and methyl methacrylate（MMA）. Such effective reducing agent significantly improved the reactivity of low reactive St monomers during the copolymerization, where the reactivity ratios of St and MMA were determined to be 0.50 and 0.36 by Finemann-Ross method. Thus the copolymerizations proceeded fast and showed typical living/controlled features, as evidenced by pseudo first-order kinetics of polymerization, linear increase in molecular weight versus monomer conversion, and low polydispersity index values. Effects of the concentration of reducing agent and the monomer feed ratio on the copolymerization were investigated in detail. Furthermore, gel permeation chromatography and 1H-NMR analyses as well as chain extension experiments confirmed the high chain-end functionality of the resultant copolymer.

关键词： Controlled/living radical copolymerization sodium hypophosphite Ambient temperature Methyl methacrylate Styrene

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Determination of Ge in Au alloys using sodium hypophosphite and potassium iodate potentiometric titration method

引用

Rare Metals 2020年第12期39卷 1492-1496页

作者： Shou-Li Han Xiao-Tang He Jun-Mei Guo Zhao-Ying Ren Li-Ya Zhu Liang-Wei Chen Qing-Nan Shi Jia-Hong Yi School of Materials Science and Engineering Kunming University of Science and TechnologyKunming650093China State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals Sino-Platinum Metals Resources(Yimen)Co.Ltd.Yimen651100China

This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather than by distillation *** influences of such conditions as the reduction acidity,the dosage of sodium hypophosphite and the reduction time on the determination of Ge were *** in AuGe alloys such as AuGe_(12),AuGeNi_(12-2),AuAgGe_(18.8-12.5),and AuAgGeNi_(43.8-6-0.2)was measured with the relative standard deviation(RSD)of 0.10%-0.31%and the recoveries of added standard Ge in sample of 99.40%-100.40%under the conditions of 0.40-0.80 mol·L^(-1)HCl,3.3 mol·L^(-1)H^(3)PO^(4),15 g sodium hypophosphite,and reduction time of40 *** new method presented is of high accuracy in results,good stability and sensibility in end-point,and easy operation and strong selectivity of determination.

关键词： Ge determination AuGe alloy sodium hypophosphite Potassium iodate Potentiometric titration

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Kinetic Spectrophotometric Determination of Trace Selenium （Ⅳ） by Its Catalytic Effect on the Reduction of Arsenazo Ⅰ with sodium hypophosphite in Micellar Media

Kinetic Spectrophotometric Determination of Trace Selenium ...

引用

2012年环境污染与大众健康学术会议

作者： Zhirong Zhou 1 , Lizhen Zhang 2 1 College of Public Health, Guangdong Pharmaceutical University, Guangzhou, China 2 The Clinic Attached to Guangdong Pharmaceutical University, Guangzhou, China

A simple and sensitive kinetic spectrophotometric method for the determination of trace selenium （Ⅳ） based on its catalytic effect on the reduction arsenazo Ⅰ （AsA Ⅰ） with sodium hypophosphite （NaH 2 PO 2 ） in a solution of 0.02 mol/L sulfuric acid and in the presence of cationic micellar media is described. The reaction rate is monitored spectrophotometrically by measuring the decrease in absorbance of AsA Ⅰ at 500 nm after a fixed time （8 min）. The decrease in the absorbance of AsA Ⅰ is proportional to the concentration of Se（Ⅳ） in the range 0.18-1.0 μg/L with a fixed time of 4-8 min from the initiation of the reaction. The limit of detection is 0.053 μg/L Se（IV）. The influence of the factors such as acidity, concentration of reactants, reactive time, temperature and co-existing ions on the reaction is discussed. The optimum reaction conditions of reaction are established and some kinetic parameters are determined;the apparent activation energy of catalytic reaction is 45.69 kJ/mol. The relative standard deviation for eleven replicate determination of 0.02, and 0.01 μg/25mL Se（Ⅳ） was 2.3 % and 2.4 %, respectively. Combined with sulphydryl dextrane gel （SDG） separation and enriching, the method has been successfully applied to the determination of Se （Ⅳ） in foodstuff and human hair samples with the relative standard deviation of 2.7 %-5.8 % and the recovery of 96.0 %-101.5 %, the results are in good agreement with those provided by ICP-AES method.

关键词： Selenium (Ⅳ) kinetic spectrophotometry arsenazo Ⅰ sodium hypophosphite micellar media

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Electroless copper-phosphorus coatings with the addition of silicon carbide (SiC) particles

引用

International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 615-622页

作者： Soheila Faraji Afidah Abdul Rahim Norita Mohamed Coswald Stephen Sipaut School of Chemical Sciences Universiti Sains Malaysia11800 USMPenangMalaysia School of Engineering and Information Technology Universiti Malaysia Sabah88999 Kota KinabaluSabahMalaysia

Cu-P-silicon carbide （SiC） composite coatings were deposited by means of electroless *** effects of pH values,temperature,and different concentrations of sodium hypophosphite （NaH2PO2·H2O）,nickel sulfate （NiSO4·6H2O）,sodium citrate （C6H5Na3O7·2H2O） and SiC on the deposition rate and coating compositions were evaluated,and the bath formulation for Cu-P-SiC composite coatings was *** coating compositions were determined using energy-dispersive X-ray analysis （EDX）.The corresponding optimal operating parameters for depositing Cu-P-SiC are as follows：pH 9;temperature,90oC;NaH2PO2·H2O concentration,125 g/L;NiSO4·6H2O concentration,3.125 g/L;SiC concentration,5 g/L;and C6H5Na3O7·2H2O concentration,50 g/*** surface morphology of the coatings analysed by scanning electron microscopy （SEM） shows that Cu particles are uniformly *** hardness and wear resistance of Cu-P composite coatings are improved with the addition of SiC particles and increase with the increase of SiC content.

关键词： electroless deposited coating electroless copper plating silicon carbide particles sodium hypophosphite hardness wear resis-tance

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Preparation and microwave absorption property of Ni/Al powder

引用

Journal of Advanced Dielectrics 2024年第4期14卷 80-91页

作者： Shen Xu Pantao Li Xiaolei Su Yi Liu School of Materials Science&Engineering Xi’an Polytechnic University No.19 Jinhua South RoadXi’an 710048P.R.China

As a functional composite material,nickel-coated aluminum powder has been widely used in conductive fillers,electromagnetic shielding materials and other fields due to its advantages of low density,high conductivity and low *** this paper,nickel-plated aluminum powder was prepared by a sodium hypophosphite *** effects of different nickel coating amounts(the percentage of nickel-plating quality to nickel-plated aluminum powder quality)on the morphology,phase,compaction resistivity and electromagnetic parameters of nickel-plated aluminum powder coating were *** X-Ray Diffraction(XRD)results proved the successful preparation of nickel-coated aluminum powders with different nickel coating *** Scanning Electron Microscope(SEM)images clearly show the coating effect under different nickel coating *** plating nickel on the surface of aluminum powder,the surface characteristics of aluminum powder are changed,so as to adjust its conductivity,resistance,stability and other properties,thus affecting its electromagnetic performance and wave absorption *** results show that the comprehensive absorbing performance is excellent when the nickel coating amount is 40%.The reflection loss of the sample with a thickness of 2.0mm is less than-10 dB in the frequency range of 10.17–12.38 *** the frequency is 10.72 GHz,the minimum reflection loss reaches33:17 dB.

关键词： Nickel-coated aluminum powder sodium hypophosphite nickel coating amount absorbing performance

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：