四氟乙烯-全氟甲基乙烯基醚共聚物的研究进展

作为可熔融加工且性能接近于聚四氟乙烯的全氟聚合物,PFA(四氟乙烯-全氟烷基乙烯基醚聚合物)得到了很快的发展并已形成了两个系列的商品.其中四氟乙烯-全氟丙基乙烯基醚共聚物(PFA-P)已经为人们熟悉,而另一类品种即四氟乙烯-全氟甲基乙烯基醚共聚物(PFA-M)却少有文献介绍.本研究对PFA-M的结构、性能、加工以及应用进行了综述.     

全氟聚氨酯-丙烯酸酯聚合物的制备与应用

为了得到具有优良防水防油性能的织物整理剂,以甲苯二异氰酸酯(TDI)、聚酯二元醇(PE1000)、N-甲基二乙醇胺(MDEA)、三羟甲基丙烷(TMP)为原料合成出交联聚氨酯,再以苯乙烯(St)、丙烯酸丁酯(BA)、全氟丙烯酸酯(FA)为单体、偶氮二异丁腈(BPO)为引发剂,通过溶液聚合制备了全氟聚氨酯-丙烯酸酯聚合物织物整理剂。本文对聚合物进行了表征并讨论了其对织物防水、防油的应用效果。实验表明,通过阳离子全氟聚氨酯-丙烯酸酯聚合物处理的织物表面对水的接触角可达136°,对石蜡油的接触角可达120°。     

氟硅聚合物/纳米SiO2杂化材料的制备与应用性能

通过本体聚合、溶胶-凝胶和接枝共聚等方法,以三氟丙基甲基-co-一甲基氢硅氧烷(PFHMS)、烯丙基缩水甘油醚(AGE)和全氟辛基乙烯(PFOE)间的硅氢化加成反应制得侧链含有全氟烷基、反应性环氧基的氟硅聚合物(PFAMS),并利用其与氨丙基三乙氧基硅烷(KH550)溶胶-凝胶改性纳米SiO2间的接枝共聚反应制备了一种...     

全氟自交联型聚醋酸乙烯酯乳液的制备及其膜性能

以烯丙基嵌段聚醚(PAB)为反应型乳化剂,采用全氟烷基乙基丙烯酸酯单体(FEA)对其进行改性,并通过羟甲基丙烯酰胺(HMA)进行自交联,以醋酸乙烯酯(VAc)、丙烯酸丁酯(BA)、甲基丙烯酸(MAA)为主要单体,通过乳液聚合法制备了全氟自交联型聚醋酸乙烯酯乳液。同时考察了全氟单体对乳液的稳定性及涂膜的常规性能及耐水性、耐候性和耐蚀性的影响。研究结果表明,当氟单体含量为4.0%时,涂膜光泽度达84.5%,硬度2H,附着力1级,柔韧性1级,耐冲击性50cm,全氟自交联醋酸乙烯酯共聚物成膜时产生了较大取向作用,含氟基团向空气/聚合物界面伸展,对聚合物内部分子形成了很好的保护作用,故全氟自交联型聚醋酸乙烯酯膜具有良好的耐水性、耐候性和耐蚀性。     

全氟烷基/聚醚/环氧侧基聚硅氧烷的制备与膜形貌

通过聚甲基三氟丙基含氢硅氧烷与乙烯基全氟癸烯、端烯丙基聚醚、烯丙基缩水甘油醚的硅氢加成反应,制备了一种全氟烷基/聚醚/环氧侧基聚硅氧烷(PFEAS).用红外光谱(IR)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、原子力显微镜(AFM)等仪器分别对产物的结构、成膜形态及性能进行了表征和研究.结果表明,在棉纤维...     

阳离子型含氟丙烯酸酯的制备及防水防油性能

以甲基丙烯酸十二氟庚酯(FM)、丙烯酸丁酯(BA)、苯乙烯(St)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)、丙烯酸十八酯(ODA)为原料,采用无皂乳液聚合制得了阳离子含氟丙烯酸酯多元共聚物乳液。对聚合物的结构、组成进行了表征研究,研究了共聚乳液膜表面的性质。结果表明,随着共聚物中全氟单体含量的增加,共聚物膜的表面能显著降低,当全氟单体的含量达到25%(质量分数)时,其表面能降低到19.99 mJ/m;并通过热处理表明了含氟单体随温度、时间增大更容易向表面富集的现象,当达到60min,120℃时水和油接触角分别达到了110°和83°。     

芯液组成对PVC-PFSA中空纤维共混膜性能的影响

以聚氯乙烯(PVC)为膜材料,N,N-二甲基乙酰胺(DMAc)为溶剂,全氟磺酸(PFSA)为添加剂,采用湿法制备了性能较好的PVC中空纤维共混超滤膜.研究了芯液组成对PVC-PFSA中空纤维膜性能的影响,研究结果表明:纯水通量随全氟磺酸浓度的增加而增加,可达1530 L/(m2·h·MPa).通过调节芯液中DMAc的含...     

二芳烯类光致变色化合物的合成及其性质

本论文合成了三种新的二芳基乙烯类光致变色化合物1-(2,5二甲基噻吩-3-基),2-[2-甲基-5-(4-甲氧苯基噻吩)-3-基]全氟环戊烯(1a),1-(2,5二甲基噻吩-3-基),2-[2-甲基-5-(4-乙氧苯基噻吩)-3-基]全氟环戊烯(2a),1-(2,5二甲基噻吩-3-基),2-[2-甲基-5-(4-氯苯基噻吩)-3-基]全氟环戊烯(3a),并且研究了它们的光电特性.实验结果表明这些二芳烯化合物在溶液和PMMA膜片中均具有良好的光致变色性能.在313nm紫外灯的照射下,这些二芳烯化合物的溶液和PMMA膜片均由无色变为蓝色,在适当波长可见光照射下,它们均从有色态返回到无色态.在不同的溶液和PMMA膜片中,这些化合物在它们各自的激发波长的照射下均显示出较强的荧光.在313nm紫外灯的照射下,二芳烯由开环态变为闭环态,荧光强度逐渐降低.     

全氟水性聚氨酯-聚丙烯酸酯纸张防油剂的制备及性能研究

为制备一种环保型水性纸张防油剂,以丙烯酸单体为溶剂,首先进行异佛尔酮二异氰酸酯(IPDI)、聚醚二醇(PTMG1000)、N-甲基二乙醇胺(MDEA)、全氟烷基乙基醇(FEOH)和丙烯酸羟乙酯(HEA)等的聚氨酯链段的聚合反应,经水乳化分散后,再进行丙烯酸单体的自由基聚合反应,制备了全氟水性聚氨酯-聚丙烯酸酯纸张防油剂。并通过红外光谱(FT-IR)、凝胶渗透色谱(GPC)、热重分析(TG)对聚合物结构性能进行了表征。同时,纸张防水防油应用实验表明,对水和液体石蜡的接触角,可分别达到130.2和113.5°,达到了优异的防水防油效果,并对纸张应用性能进行检测,可以满足日常生活中特种纸的要求。     

苏联氟橡胶的性能

1959年前后,苏联开始工业生产氟橡胶。从目前大量的资料报导来看,其生胶品种除通用型的偏氟乙烯类氟橡胶(-32,-26,-246)外,还有具有苏联自己特色的偏氟乙烯和全氟烷基乙烯基醚的共聚物-260及其改性橡胶-260,以及四氟乙烯、全氟甲基乙烯基醚共聚物-460及含第三单体的-460A,     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。