基于Wilhelmy法的单一炭纤维/环氧树脂动态接触角测量及表面能表征

基于Wilhelmy法对日本东丽T700炭纤维/BA202环氧树脂体系动态接触角的测量方法进行研究,利用测试得到的"润湿回线"分析探讨炭纤维与树脂间的浸润过程,并基于此"润湿回线"进行测试条件优化,得到最佳测试条件为纤维伸出测量夹具4 mm、纤维浸入树脂深度2 mm、检测速度1 mm/min、检测阈值0.0002 g和炭纤维单丝根数6根。最后通过测试炭纤维上浆前后与树脂的接触角变化及计算对应的纤维表面能及其组成的变化,得出该表面上浆剂能够提高T700炭纤维的表面能,降低纤维接触角,增强纤维与基体树脂间的结合力,提高其浸润性能的结论。     

粒状发射药接触角测定条件的优化

为获得较为准确的粒状发射药的表面性能参数,采用接触角测量仪测量了粒状发射药在不同实验操作条件下的接触角,讨论了躺滴法测量发射药接触角操作过程中测试面的选取、测试面的处理方式、所用液滴体积、液滴与发射药测试面的接触时间等因素对接触角测定值的影响。依据实测数据确定了较为稳定的实验操作条件:用磨平的粒状发射药侧面作为接触角测试面,对测试面采用细砂纸打磨后再用丙酮擦拭、晾干的处理方式,所用液滴体积不大于1μL,取液滴与测试面的接触时间为8s时的接触角值作为测试结果。     

玻璃纤维密度测试技术应用评估

基于玻璃纤维密度测试技术，分析最常用的3种测试方法：密度天平法、液体比重法、气流法，并应用这3种方法测定玻璃纤维行业典型粗纱和细纱的纤维密度，同时评估方法的测试偏差。结果表明：密度天平法测定的重复性偏差为±0.0100 g/cm 3，液体比重法测定的重复性偏差为±0.0200 g/cm 3，气流法测定的重复性偏差为±0.0005 g/cm 3，气流法测定的重复性偏差最低。分析原因：气流法测试玻璃纤维密度时，没有玻璃纤维的多次取放过程，去除了玻璃纤维毛羽、粘连等问题对纤维密度测试的影响，同时气流法测定时气体介质与玻璃纤维的接触更加充分，去除了纤维气泡的影响。     

表面改性高模高强碳纤维与环氧树脂界面相容性研究

采用阳极氧化法对高模高强碳纤维表面改性,改性后上浆处理。经润湿性能测试,改性后碳纤维的接触角由改性前的66.3°降至27.8°,表面活性增加,润湿性能改善。采用扫描电镜和原子力显微镜对其表面结构进行表征,发现改性后碳纤维表面粗糙度增加,分散性较好。对其环氧树脂复合材料进行力学性能测试,结果表明复合材料界面剪切强度和层间剪切强度分别增至42.3 MPa和43.6 MPa,且增加程度与纤维表面粗糙度成正比。     

水处理滤料润湿性能测定方法的比较研究

根据Washburn方程,采用高度法和压力法测量滤料接触角,引入亲油亲水比(RLH)的概念,以正辛醇和去离子水作参比液,得出了25℃下核桃壳和石英砂滤料的亲水亲油比值。结果表明,压力法更适合滤料接触角测量,核桃壳颗粒对于非极性液体的润湿性较好,石英砂对于极性液体的润湿性较好,本研究为含油废水处理滤料的润湿性能改进提供一种新思路。     

微波辐射改性秸秆/HDPE复合材料的界面性能

利用微波接枝偶联剂处理秸秆纤维,采用光学法液滴形态分析系统测定3种不同方法处理的秸秆微粉的动态接触角及表面能变化,并制备相应的复合材料进行力学性能测试.研究结果表明:几种界面改性方法对秸秆微粉均有较好的改性效果,微波/KH550改性效果最佳,微波/钛酸丁酯次之,再次为直接微波处理.经微波处理后秸秆纤维的平衡接触角θe由40.26°上升到42.97°,经微波/钛酸丁酯处理后平衡接触角θe由40.26°上升到50.33°,而发现经微波/KH550处理后平衡接触角θe由40.26°上升到94.01°.而表面能则有不同程度减小,经微波/KH550处理后秸秆纤维表面能接近HDPE基体;经界面改性处理的秸秆纤维,其复合材料的拉伸强度提高0.40%～19.79%,冲击强度提高7.21%～15.29%.动态接触角法研究液体润湿微粉的动力学特性具有快速、准确、操作简单的特点,为研究植物纤维表面改性接枝等提供理论基础.     

炭黑粉末润湿性质的研究

炭黑润湿性能的研究是炭黑性质研究的重要内容,润湿是指液体从固体表面取代气体的过程。润湿过程涉及固体和液体的表面性质,以及固液分子间的相互作用。在研究炭黑的润湿作用时,接触角大小是衡量润湿性优劣的较为方便的方法。通过动态法测定了接枝炭黑和未接枝炭黑在某些溶剂中的接触角,考察了接触角的变化规律。结果表明,炭黑表面接枝水溶性高分子将明显改善其润湿性质。     

表面处理对碳纤维润湿性及连续纤维增强PEEK复合材料拉伸性能的影响

用5种工艺对碳纤维进行表面处理,并与PEEK薄膜热压成复合材料。采用润湿天平法检测碳纤维表面的润湿力并进行SEM表面形貌分析;测试试样拉伸性能并观察试样断口形貌。结果表明:混酸超声处理法处理的碳纤维表面粗糙度最大,润湿性最好,表面润湿力达到0.82mN,用其制备复合材料的拉伸性能最佳。     

α-氰基丙烯酸乙酯粘合剂的静电喷雾沉积研究

以α-氰基丙烯酸乙酯(ECA)为静电喷雾溶液,采用传统静电喷雾装置,着重考察了施加电压和温度因素对静电喷雾沉积的影响以及PECA聚合薄膜的组分分析、热稳定性能和表面润湿性能。研究结果表明:对于给定的ECA溶液,理想的锥-射流稳定模式的电压范围为5.8～8.0 kV;随着温度的升高,其沉积率和聚合率都明显下降;静电喷雾沉积PECA薄膜外延起始分解温度为184℃,中心区域表面润湿接触角为69.46°。     

PTFE中空纤维膜表面改性及组件浇铸技术的研究

采用浸渍丙烯酸、丙烯酸丁酯、复配功能性溶液和等离子体接枝丙烯酸的处理方式对聚四氟乙烯中空纤维膜进行改性处理,在中空纤维膜表面沉积、接枝活性层,改善聚四氟乙烯中空纤维膜表面的润湿性和黏结性能,并与传统钠萘溶液处理的改性效果进行了比较。通过扫描电镜(SEM-EDX)、傅里叶变换衰减全反射红外光谱(ATR-FTIR)、接触角测试表征聚四氟乙烯膜改性前后表面的形态结构及润湿性能。研究表明,浸渍丙烯酸溶液的中空纤维膜表面沉积了聚丙烯酸活性层,润湿性能提高;等离子体接枝丙烯酸改性处理的中空纤维膜表面引入了—COOH,—C=C—等活性基团,润湿性能有所改善。通过拉伸黏结强度、渗漏压力测试聚四氟乙烯中空纤维膜组件中中空纤维膜与胶黏剂间的黏结强度。结果表明,浸渍丙烯酸、丙烯酸丁酯、复配功能性溶液的中空纤维膜的最大拉伸载荷分别为61.9、58.5、43.5 N时从胶黏剂中滑脱,当水压达到0.15 MPa时均出现了渗漏;等离子接枝丙烯酸处理的中空纤维膜的最大拉伸载荷为60.9 N,并且在0.15 MPa的水压下未发生渗漏,适用于膜组件浇铸。     

润湿天平法测量纤维接触角的研究

根据润湿力测量原理,设计了一套用精密电子天平测量纤维接触角的装置。对丙纶的接触角进行了测量,并对纤维长度、入水深度和平衡时间等对接触角的影响进行了重点研究。结果表明:该方法实用可靠,纤维露出长度在5mm左右,入水深度在2mm时重现性比较好。     

A novel method for measuring dynamic contact angles of fibers with spindle-knots

The determination of the dynamic contact angle is of significant interest for the characterization of the wettability of technical fibers and textiles in diverse fields of science and technology. There exist traditional methods for dynamic contact angle measurements of flat surfaces and of fibers with a uniform cross-sectional shape along the fiber. So far, however, no method has been reported which is suitable for structured fibers, particularly for spindle-knotted structured fibers of varying cross-sections. This article describes a new method for measuring the dynamic contact angle for polydimethylsiloxane (PDMS) spindle-knotted structured fibers. The method is an outcome of integrating the results obtained from experiments (applying force tensiometry) and a proposed theoretical model describing such fibers. The reliability and conformity of the results are shown by comparing the measured dynamic contacts angle of PDMS as spindle-knot and as a flat surface. This method may pave the road for better wettability analysis of various structured fibers. It also allows to measure the local receding and advancing contact angles for macroscopic/microscopic structured fibers (especially when they are not accessible as flat surfaces) against the various test liquids.     

Wetting properties of human hair by means of dynamic contact angle measurement

The interaction between human hair and water occurs continuously in atmospheric air, and even more so, during application of shampoo and conditioner. For this reason the wettability of hair, and how hair care products affect the wetting properties, is of interest to hair care science. In this study, the Wilhelmy balance method is used to measure dynamic contact angle of both conditioner‐treated hairs and those left untreated to study the interaction of hair with water. The method uses a microbalance to measure the force exerted on a single fiber when it is immersed into the wetting liquid of interest. This measured force is related to the wetting force of the liquid on the fiber, and the dynamic contact angle can be calculated. The contact angles of chemically damaged, mechanically damaged, virgin (undamaged) as well as conditioner‐treated hairs and those left untreated are measured and compared. These samples were measured dry, and then also allowed to soak in water before being measured to determine whether a wet environment affects the wetting properties of the hair surface. Additionally, wettability of hairs from subjects of different ethnicities are measured and compared. Further, the mechanisms driving a significant directionality dependence are studied and discussed. The results are also used to explain tribological properties found in previous studies. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5255–5265, 2006     

接触角法在测定固体表面洁净度方面的应用

介绍了接触角法测定固体表面洁净度的基本原理,接触角的测定方法,包括量角法,测高法(小液滴法和平衡液滴法)。影响接触角法测定准确的主要因素为表面粗糙度,此外温度变化及平衡时间对接触角也略有影响。接触角法在生产中的具体应用有水滴法、水膜法和喷雾法,讨论了它们在测定物体洁净度和判断清洗方法优劣方面的应用。     

纳米结晶纤维素表面修饰聚酰亚胺纤维及其润湿功能性

聚酰亚胺纤维在应用方面存在许多潜在问题，例如聚酰亚胺纤维的低表面活性，使得其界面的润湿性能差，且在水相中易团聚，分散性较差。为此，本文提出在复合路易斯酸及交联剂共同催化作用下，使纳米结晶纤维素（CNC）修饰碱处理后的聚酰亚胺（PI）短切纤维表面，测定了CNC修饰前后PI纤维在水溶液中的分散度及PI纤维成纸的接触角，结果表明PI纤维的浸润功能性得到提高。采用扫描电子显微镜（SEM）观察了纤维的微观形貌，利用傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）表征了纤维表面结构的变化，最后通过多孔材料孔径分析仪测定了纤维成纸的孔径分布变化。结果表明：经CNC处理后的纤维表面发生了酯化反应且存在交联现象，纤维表面氧元素物质分数增加，含氧极性基团和表面粗糙度的增加有助于改善润湿性能，与PI纤维原纸相比，经CNC表面修饰后的纤维所成的纸页与去离子水的接触角降低了14.9°，与乙醇的接触角降低了4.8°，纤维分散度增加了45％，纤维亲水性显著提高，经过表面处理后的纤维在水相体系中的分散性能得到改善。因此，本法可以作为制备高性能纤维和相应复合材料的有效方法。     

Direct measurement of molten poly(ethylene terephthalate) contact angles on single aminopropylsilane coated glass fibers

The kinetics of spreading of molten poly(ethylene terephthalate) (PET) on aminopropylsilane (APS) treated glass fiber surfaces has been studied. The modified Wilhelmy wetting method was used for contact angle determination with small diameter fibers (10-100 μm) used as vertical wetting probes. It is shown that the small meniscus dimensions accelerates wetting, and viscous relaxation effects can be kept to a minimum, so that purely surface effects can be studied in terms of the equilibrium contact angle at elevated temperatures. Experiments were performed using single fibers coated with a 'reactive' coupling agent (APS) in this laboratory. Although complete spreading of PET at 270°C was not initially observed, zero contact angle was eventually obtained due to interfacial chemical reaction between APS and PET. The suggestion that complete spreading is driven by the interfacial reaction was supported by a study of glass fibers coated with a non-reactive silane. In that case, a large initial contact angle was observed but zero contact angle was never obtained. The equilibration rate to = 0° was much faster on bare glass than APS coated glass for PET at 270°C because complete spreading is thermodynamically favorable on bare glass. Data for commercial silane treated 10 μm fibers in terms of the wetting rate in molten PET at 270°C were comparable to that for the APS coated fibers.     

Capillary wetting rates in nylon fibrous assemblies

The capillary wetting rates in nylon fibrous assemblies were evaluated from the change in electrical conductivity due to wetting. The wetting liquids used were aqueous potassium chloride solutions of various pHs, in both the absence and the presence of ionic surfactants. Sodium dodecyl sulfate and dodecyltrimethylammonium chloride were chosen as surfactants. The contact angles of the wetting liquids on the nylon fiber were measured by the Wilhelmy method and the isoelectric point of the fiber was determined from electrokinetic data. The minimum wetting rate and the maximum contact angle were observed near pH 4, which coincided with the isoelectric point of the nylon fiber. In the presence of surfactant ions, the minimum wetting rate was also obtained at the concentration where the surface charge of nylon was neutralized. These experimental findings indicate that the capillary wetting rates in nylon fibrous assemblies are influenced by the electrical phenomena at the nylon/ solution interfaces via the contact angle and the structure of the adsorbed surfactant layers.     

纤维表面冷等离子体处理对其表面性能的影响

本文采用冷等离子体技术来处理碳纤维、芳纶纤维与聚酯纤维，处理后纤维表面活性基团、浸润量与浸润速度增大，而接触角与浸润过程活化能降低，说明纤维浸润性是得到了很大的改善。     

THE EFFECT OF SUBSTRATE GEOMETRY ON DYNAMIC CONTACT ANGLES IN SURFACE WETTING

Dynamic contact angles play a central role in the problem of wetting of surfaces. A solid surface is moving steadily through the free surface of a liquid. The angle between the plunging solid surface and the liquid free surface at the line of solid-liquid contact is the dynamic contact angle. This work compares experimentally measured dynamic contact angles of horizontally rotating rolls of different diameters with those of circular fibers, and tapes. The comparison also includes dry and pre-wet surfaces. Dynamic contact angles depend on the geometry of the wetted substrate. Specifically the geometry through its curvatures affects the surface tension forces at the contact line. Smaller diameter rolls generate smaller angles. In wetting of circular fibers the angles are the smallest compared to tapes and rolls. Flat dry tapes form the largest angles when they are wetted. This implies that the curvatures of the circular rolls and fibers contribute to the balance of surface energies at the contact line. Pre-wet surfaces generate considerably smaller angles at the same wetting speeds. In contrast with that, the diameter of rolls does not affect the critical speed of air entrainment.     

Liquid/Fiber and Solidified-Liquid/Fiber Contact Angles Compared

Data are presented showing that the contact angle formed by a liquid resin droplet placed on a single fiber is comparable with a receding contact angle. This was ascertained by comparing Wilhelmy wetting force measurements with liquid droplet profile analysis. Subsequently, the latter analysis was carried out on cured (solidified) epoxy droplets placed on Kevlar fibers. Dimensional changes observed after curing showed that the contact angles of the solid droplets were smaller than that for liquid resin: however, the presence of residual stresses because of adhesion to the fiber may make droplet profile analysis inaccurate for obtaining an equilibrium receding contact angle for the solid droplets.