Teflon AF-2400管冷蒸气发生-原子荧光法分析烟草中的痕量汞

采用具有高气体渗透性和紫外光透过性的无定形聚四氟乙烯管(Teflon AF-2400)作为蒸气发生原子荧光系统的气液分离器和检测池,建立了微型化汞蒸气发生原子荧光检测系统.考察了Teflon AF-2400管长度、还原剂种类和浓度、酸介质种类和浓度、进样流速以及氩气流速对测量体系的影响.在优化实验条件下,该方法的线性范...     

Research Deyelopment of Composite Coating of Polyphenylene Sulfide and Polytetrafluroethylene

聚苯硫醚、聚四氟乙烯均是耐高温、耐腐蚀的树脂,同时聚四氟乙烯有极低表面能,而聚苯硫醚与金属有良好结合力,结合二者的优点,有望制备出集合耐腐蚀、耐高温、超疏水等优异性能为一体的功能涂层,因此以聚苯硫醚、聚四氟乙烯为主要原料的复合涂料自1992年以来便倍受关注。本文从聚苯硫醚、聚四氟乙烯各自的性能出发,综述了聚苯硫醚／聚四氟乙烯复合涂层三种不同制备工艺：分层涂覆、共混涂覆、梯度涂覆;详细说明了涂层的五大优异性能：耐腐蚀性、超疏水性能、阻垢性能、耐高温性以及耐磨性能,最后本文还描述了聚苯硫醚／聚四氟乙烯复合涂层的广阔应用前景。     

聚苯硫醚/聚四氟乙烯复合涂层研究进展

聚苯硫醚、聚四氟乙烯均是耐高温、耐腐蚀的树脂,同时聚四氟乙烯有极低表面能,而聚苯硫醚与金属有良好结合力,结合二者的优点,有望制备出集合耐腐蚀、耐高温、超疏水等优异性能为一体的功能涂层,因此以聚苯硫醚、聚四氟乙烯为主要原料的复合涂料自1992年以来便倍受关注。本文从聚苯硫醚、聚四氟乙烯各自的性能出发,综述了聚苯硫醚/聚四氟乙烯复合涂层三种不同制备工艺:分层涂覆、共混涂覆、梯度涂覆;详细说明了涂层的五大优异性能:耐腐蚀性、超疏水性能、阻垢性能、耐高温性以及耐磨性能,最后本文还描述了聚苯硫醚/聚四氟乙烯复合涂层的广阔应用前景。     

高硅SAPO-34与聚四氟乙烯复合材料的合成

以二乙胺为结构导向剂, 在聚四氟乙烯乳液中水热法合成了高硅SAPO-34与聚四氟乙烯复合材料. XRD表明合成样品为SAPO-34结构, SEM照片表明型貌完好, 周围牢固地覆盖着聚四氟乙烯材料. 与不加聚四氟乙烯乳液合成样品相比, 添加后晶粒尺寸增大, 晶型更完好, 疏水和成膜性能提高.     

辉光放电质谱新方法分析颗粒状金属铪

采用直流辉光放电质谱方法((dc-GD-MS)分析颗粒状((2mm×1mm×1mm)金属铪中的杂质元素.本方法解决金属铪样品尺寸太小难以直接进行辉光放电质谱分析的问题.采用聚四氟乙烯管(内径2.3 mm×外径3.2 mm)与医用注射器连接并密封接口,再将粒状铪置于管子前端(管长的1/3处),接着将PTFE 管水平插入已...     

逆流色谱的基本关系式

前言 逆流色谱(Countercurreut Chromatography,简称CCC)是一种特殊形式的液-液分配色谱。它不使用固体支持介质,柱材料为空的聚四氟乙烯管(PTFE)或玻璃管。选用不相混溶的两相溶剂系统,其中一相作为固定相并依靠重力或离心力保留在柱中,另一相则作为流动相。被分离的各组分依据其在两相中的分配系数的差异得到分离。由于CCC不使用固体支持介质,因而避免了因不可逆吸附而引起的样品损失、失活变性及失真等,使得样品可以全部回收。     

气相色谱-原子吸收联用技术测定人体体液中烷基汞

建立了一种用于生物样品中分子形态分析的气相色谱与原子吸收联用系统。系统的转移线为聚四氟乙烯管,组分在色谱住内分离后,经转移线运送到原子吸收检测系统。实验证明:系统具有灵敏度高、选择性好的优点,例汞绝对检测限为10-2ng,并首次用于人体血液和尿液中烷基隶的两种形态即氯化甲基汞和二甲基汞的定性和定量分析。     

一种简易鉴别聚四氟乙烯的红外光谱法

聚四氟乙烯有“塑料王”之称,没有特殊的化学反应可用来鉴别这种氟塑料。为了鉴定工业制品中是否存在聚四氟乙烯,通常     

高分子固载钴酞菁的合成及其催化硫醇氧化的性能

利用预辐照、共辐照接枝方法合成了聚四氟乙烯-接-聚丙烯酰胺,并与二乙烯三胺径过胺交换反应得到了胺化的聚四氟乙烯-接-聚丙烯酰胺双功能载体,并用红外,元素分析的方法对胺交换前后的接枝聚合物进行了初步表征。     

Cds纳米微粒的聚四氟乙烯多孔膜法制备及其表面修饰

硫化镉;Cds纳米微粒的聚四氟乙烯多孔膜法制备及其表面修饰;纳米粒;多孔膜;表面修饰;聚四氟乙烯     

Electroless Ni-plating on PTFE fine particles

A Ni electroless plating process was used with polytetrafluoroethylene (PTFE) fine particles (25–500 μm). Using nonionic hydrocarbon surfactant, PTFE particles were dispersed in the plating bath. The PTFE hydrophobicity was sufficiently high that Ni was deposited partly on the PTFE surface in the initial step. The Ni-PTFE particles were formed into the Ni-PTFE plate by heat treatment at 350 °C after pressing. The Ni-PTFE plate had electrical conductivity and gas permeability, which were influenced by the pore distribution in the plate. Pores with 1 μm diameter might be especially important to impart high gas permeability to the Ni-PTFE plate.     

A microporous membrane-based continuous generation system for trace-level standard mixtures of atmospheric gases.

A reliable and convenient system to generate accurate and stable standard gas mixtures of various atmospheric compounds at parts-per-billion levels has been developed. The system is of simple design; the generator is a coil consisting of an inner tube of microporous polytetrafuluoroethylene (PTFE) membrane tubing and an outer tube of silicone tubing. An aqueous solution of the given compound continuously flows through the inner microporous tube and the purge gas flows through the annulus between the inner and outer tubes. In addition to the generation of gas mixtures based on Henry's law, the proposed flow-type system offers generation based on chemical reactions, leading to a distinct advantage of the availability of continuous sources of various compounds. The generation system was tested for preparing standard gas mixtures of HCHO and H2O2 on the basis of Henry's law, and those of HNO2, NO, and SO2 on the basis of chemical reactions. A stable generation of the desired low concentrations of various kinds of gas mixtures can be readily achieved by adjusting the concentration of the solution without the use of high-dilution flow.     

气体扩散层中聚四氟乙烯的分布对质子交换膜燃料电池水淹的影响

通过在不同真空度下进行碳纸的聚四氟乙烯（PTFE）浸渍处理,考察了PTFE在碳纸中的分布对燃料电池水淹情况的影响. 碳纸PTFE浸渍过程中,抽真空作用可以将碳纸微孔中存留的空气移除,使PTFE更均匀地扩散到内部微孔中. 碳纸的断面电镜照片显示真空浸渍可以改善PTFE的分布. 在总浸渍量相同时,由于真空浸渍使更多的PTFE进入到碳纸内部微孔,故其表面的PTFE比例减少. 实验进一步考察了碳纸中亲水孔和憎水孔的分布,结果表明真空浸渍处理的碳纸具有更高比例的憎水孔. 将不同处理方法的碳纸制备成膜电极,通过全尺寸电池考察其性能,结果表明PTFE的均匀分布可以改善电池性能,并且电化学阻抗分析表明其有利于改善水淹问题.     

含脂肪链聚苯并咪唑的合成及其气体透过性能

对含脂肪链聚苯并咪唑的聚合反应进行了比较系统的研究，在此基础上，合成了一系列含脂肪链聚苯并咪唑．以甲酸为溶剂，在减压下，制备了聚合物的均质膜．对聚合物的气体选择透过性能进行了研究，并从化学结构与气体透过性能关系的角度进行了讨论，发现同一聚合物对不同气体的透过系数符合一般玻璃态聚合物的规津；增加柔性链段中亚甲基数目，可提高聚合物的气体透过系数，降低分离系数；刚性链段中引入柔性基因，可增大气体透过系数；温度升高，聚合物的气体透过系数提高，分离系数一般下降．     

Instrument for generation of volatile organic compounds for the development of chemical sensors and evaluation of tube-type diffusive sampling

An automatic calibration apparatus for the dynamic generation of organic vapours was developed. The accurately controlled stream of nitrogen was drawn at a low flow-rate through a thermostated container filled with the standard substance, thus generating a continuous stream of saturated vapour of the compound. The compound holder vessel was thermostated at −16°C. A large stream of pure carrier gas was mixed with a low stream of substance in a mixing chamber for dilution. The fittings were manufactured from PTFE, and tubes were made of special PTFE with an inert inner surface to eliminate the wall adsorption and to decrease the cross-diffusion. Moisture interferences were reduced using a Nafion membrane filter. The vapour generator was validated by diffusive sampling and gas chromatographic methods. Standard mixtures have been prepared containing toluene at concentrations ranging from 3 to 3000 ppm. The combined uncertainty of preparative and analytical error components associated with the concentration of the analytes at the 95% confidence level typically ranges from 2 to 5% relative, depending upon the concentration. The measured and the calculated values were compared and good correlation (r²>0.99) was found.     

Study of a new novel process for preparing and co-stretching PTFE membrane and its properties

A new idea regarding improvement of the elastic recovery property of a PTFE/PU compound membrane through a co-stretching process was put forward. The experimental results show that the PTFE/PU membrane has great elastic recovery owing to PU. When the longitudinally stretching ratio of PTFE is 200%, the traverse stretching ratio is 850%, and the thickness of PU is 0.03 mm. When the longitudinally and traverse elastic recovery of PTFE/PU is 82.1% and 88.6%, respectively, the porosity is 78.0%, mean pore size is 0.382 μm, and the water vapour permeability is 9330 g/24 h m². It has been used for the SARS protective clothing in China.     

PTFE Electrospun Stent Graft——Preparation,Properties and Its Industrialization Prospect

Stent graft(SG), isolating the diseased vessels from the normal blood circulation and preventing the rupture of the aneurysm wall in minimally invasive surgery, is normally composed of a metallic stent and a cover with a textile structure. In this study, the electrospinning method was used to prepare a new type of cover, and the preparing conditions and the performance of the SG were investigated. The polytetrafluoroethylene(PTFE) and polyethylene oxide(PEO) were blended at the ratios of 99:1, 98:2, 97:3 and electrospun to form precursor membranes. Then they were dried in a vacuum and sintered at different temperatures under different time periods to obtain PTFE membrane, which was compounded with a stent. Their morphology, mechanical properties, water permeability and biological properties were studied. The results showed that when the membrane was sintered at 380℃ for 10 min, it had the best tensile properties. The integral water permeability of the PTFE electrospun SG was close to 0. The hemolysis rate of the SG was 2.84%, and human umbillical vein endothelial cells(HUVECs) can adhere and proliferate well on the surface of the PTFE membranes. The PTFE electrospun SG had great potential for clinical application and industrialization.     

Effects of Tube Materials on Capillary Chromatography Based on Tube Radial Distribution of Ternary Mixture Carrier Solvents under Laminar Flow Conditions

A capillary chromatography system was developed using an open capillary tube and a ternary solvents carrier solution of water-hydrophilic/hydrophobic organic solvent mixture. The chromatography is called a tube radial distribution chromatography (TRDC) system. The TRDC system works without applying high voltages or using specific columns, such as monolithic and packed columns. In this study, the effects of tube materials on separation performance were examined in the TRDC system, by using poly(tetrafluoroethylene) (PTFE; 100–400?μm inner diameter), polyethylene (PE; 200?μm inner diameter), and copolymer of (tetrafluoroethylene–perfluoroalcoxyethylene) (PTFE–PFAE; 100?μm inner diameter) capillary tubes. An analyte solution of 2,6-naphthalenedisulfonic acid and 1-naphthol as a model was subjected to the system with a water–acetonitrile–ethyl acetate carrier solution; 15:3:2 volume ratio (water-rich carrier) and 3:8:4 volume ratio (organic solvent-rich carrier). The flow rates were adjusted to be 0.5?μL?min^?1 for PTFE and PTFE–PFAE tubes as well as 2.0?μL?min^?1 for PE tube under laminar flow conditions. These analytes in the solution were separated in this order with the water-rich carrier solution with baseline separation in the three capillary tubes, while they were eluted in the reverse order or not separated with the organic solvent-rich carrier solution. The effects of tube temperature on separation were also examined with the water-rich carrier solution; the best resolutions were observed at 0?°C of the tube temperature. The obtained results were compared with those of fused-silica capillary tube and discussed.     

三甲基硅取代PPO和三苯基硅取代PPO及其气体选择透过性能

讨论了聚２，６－二甲基－１，４－苯撑氧（ＰＰＯ）与三甲基氯硅烷和三苯基氯硅烷的反应，合成了一系列取代含量不同的三甲基硅取代ＰＰＯ（ＴＭＳ－ＰＰＯ）和三苯基硅取代ＰＰＯ（ＴＰＳ－ＰＰＯ）．研究了取代基团不同和取代含量变化对聚合物的气体选择透过性能的影响，发现ＴＭＳ－ＰＰＯ的气体透过系数随三甲基硅取代量加大而增高，分离系数下降；ＴＰＳ－ＰＰＯ的气体透过系数和分离系数都随三苯基硅取代量的增加而下降，ＴＰＳ－ＰＰＯ与ＴＭＳ－ＰＰＯ的气体溶解系数相近，扩散系数差别较大．故二者气体透过系数的不同主要是由于扩散系数的差异．从化学结构与气体透过性能关系的角度来看，若在聚合物分子中引入有较小转动自由能的大基团，则有利于气体分子的扩散透过．     

Composites Based on Polytetrafluoroethylene and Detonation Nanodiamonds: Filler–Matrix Chemical Interaction and Its Effect on a Composite’s Properties

Specific properties of PTFE composites filled with ultradisperse detonation diamonds (UDDs) with different surface chemistries are studied. It is found for the first time that filler in the form of UDDs affects not only the rate of PTFE thermal decomposition in vacuum pyrolysis, but also the chemical composition of the products of degradation. The wear resistance of UDD/PTFE composites is shown to depend strongly on the UDD surface chemistry. The presence of UDDs in a PTFE composite is found to result in perfluorocarbon telomeres, released as a readily condensable fraction upon composite pyrolysis. The chemical interaction between PTFE and UDDs, characterized by an increase in the rate of gas evolution and a change in the desorbed gas’s composition, is found to occur at temperature as low as 380°C. It is shown that the intensity of this interaction depends on the concentration of oxygen-containing surface groups, the efficiency of UDDs in terms of the composite’s wear resistance being reduced due to the presence of these groups. Based on the experimental data, a conclusion is reached about the chemical interaction between UDDs and a PTFE matrix, its dependence on the nanodiamond surface chemistry, and its effect on a composite’s tribology.