Influence of Drying Method on Enzymatic Stain and Contact Angle of Maple

Lumber enzymatically stained has a significantly reduced value. The process involved in producing this degradation has not been well characterized. The influence of temperature and fluid flow transport of sap solutes were probed using contact angle analysis. Temperature effects on surface chemistry, as detected by polar components, was identified but was found not to attribute to staining. Dispersal components, used to indicate fluid flow transport of solutes, pointed to a positive influence on the production of stain. A more detailed layer-by-layer analysis was discussed to provide a more definitive conclusion of attributing the degree of staining to fluid flow transport of sap solute.     

有机液体在粉末上接触角的测定研究

得到了一系列有机液体在粉末上的接触角的数值和表面活性剂在这些粉末上表现的性质,并做了定性和定量分析。实验原理建立在把渗透的液体进入玻璃管内粉末形成的多孔塞基础上,将Washburn方程用于毛细管内液体的流动用于计算液体和粉末之间接触角大小。结果显示了有机液体分子在石墨、铝粉上表面吸附的细节,并讨论其在科研和生产实践中的应用。     

接触角的研究现状及其在凝胶干燥中的作用简

接触角是固体表面润湿性能的重要参数之一。根据接触角可以获得固体表面的固-液、固-汽界面的许多信息。本文简要介绍了接触角在凝胶干燥中的作用,并对接触角的相关理论研究、实验测量方法以及分子动力学模拟研究进行综合评述。     

Contact Angle Equilibrium on Thin Elastic Solids

A theoretical analysis has been carried out on the system consisting of an axisymmetric sessile drop resting on a thin elastic solid in the presence of gravity. The solid is treated in one case as a thin plate and in the other case as a membrane. The consequences of the variational treatment employed are equations relating to contact angle equilibrium, drop and solid profiles. It is shown that contact angles are not intrinsic surface properties of the phases involved but invoke equally such characteristics as bulk properties of the solid and physical dimensions when the solid in question is deformable.     

Specific Interactions and Contact Angle Measurements on Polymer Solids

The present work examined the susceptibility of contact angle data to specific interactions taking place between solids and contacting liquids. The polymers involved were polystyrene, polyvinyl chloride and polyethylene, representing respectively basic, acidic and neutral substrates. Contacting fluids also were chosen to represent acid and base interaction categories.

Significant time-dependent changes in contact angles were observed when acid/base pairs were involved in the experimental sequence. In specific cases it was possible to identify initial (zero contact time) contact angles, as well as equilibrium values, attained after prolongued contact times. Local solvation, or plasticization, of the polymer by the wetting fluid was postulated as the operative mechanism. The differences between initial and final values of the contact angles were correlated with parameters of specific interaction, calculated from the acceptor/donor numbers for the pertinent materials as measured by inverse gas chromatography. In contrast, when acid/acid or base/base combinations of polymer and wetting fluid were studied, equilibrium values of the contact angle were established rapidly. Since accurate information on acid/base properties of polymers and wetting fluids is not always available, it seems prudent to record contact angles as a function of contact time, and by extrapolation to determine the initial (true) value for further use in surface characterizations of polymers.     

Contact Angle of Ethanol and n‐Propanol Aqueous Solutions on Metal Surfaces

The contact angles of the aqueous solution of ethanol and that of n‐propanol on copper, aluminum, and stainless steel surfaces are reported. The contact angles were measured under atmospheric conditions, and then under vapor‐liquid equilibrium conditions at 1 atm and different temperatures. The results showed the variations of the contact angles with the concentrations of aqueous solutions on different metal material surfaces with different roughness. Some unstable behavior of the wetting ability around the azeotropic point of a binary solution is reported. Influences of concentration, kind of materials, and the surface roughness on the wetting ability are discussed. The model for predicting the contact angle of alcohol aqueous solutions on metal surfaces under atmospheric and vapor‐liquid two‐phase equilibrium conditions at 1 atm is derived from the Young equation.     

用接触角法测量聚合物共混体系的表面性能

利用接触角的方法研究了聚合物HDPF、PET及其共混物HDPE／PET的表面自由能、极化度以及与不同液体一水和甘油间界面张力的大小。     

高度法和压力法测定粉末接触角的比较

粉体接触角的测定有着十分重要的理论和实际应用意义。根据Washburn方程,在渗透法测定粉末接触角的基础上,引入相对接触角的概念,并设计了测定石墨粉相对接触角的试验装置,以苯作为参比液,用高度法和压力法分别测定了25℃下蒸馏水对石墨粉的相对接触角,它们分别为83.50°和83.74°。试验结果表明,压力法和高度法均可用于粉末接触角的测定。     

羧甲基纤维素钠对表面张力和接触角的影响

本文利用各种样品的表面张力和接触角的实验数据,说明羧甲基纤维素钠对洗涤作用的影响。     

Characterisation of Fuel Cell Membranes as a Function of Drying by Means of Contact Angle Measurements

In another paper in this volume, it is demonstrated that the electrochemical interface in MEAs, and thus the polarization performance of the resulting fuel cells, can be improved by optimising the hot‐pressing procedure in the MEA preparation. In particular, the extent of drying of the membrane during MEA preparation was shown to be critical. In the present investigation, the effect of the drying process, and thus water content, on the hydrophilicity, wetting, and surface energies of some fuel cell membranes is examined. Wetting and surface energies are well known to influence the bonding behaviour of materials. Conclusions about how membrane drying and changes in water content influence membrane bonding and the relative importance of these surface effects are drawn.     

Coating and Drying in Spouted Bed: Influence of the Liquid-Particle Work of Adhesion

The aim of this work is to analyze the resulting process: coating or drying, and the respective fluid dynamic behavior, by bottom-spraying polymeric suspensions on a spouted bed of inert particles. Glass beads, ABS®, polypropylene (PP), and polystyrene (PS) were chosen as inert particles and were analyzed and characterized by their physicochemical properties. The polymeric suspensions were characterized by density, surface tension, rheology, and wettability. The fluid dynamic behavior of the bed was correlated with the particles and suspensions characteristics for each process: coating and drying. Each process performance was correlated with the polymeric suspension-particle work of adhesion.     

Coating and Drying in Spouted Bed: Influence of the Liquid-Particle Work of Adhesion

The aim of this work is to analyze the resulting process: coating or drying, and the respective fluid dynamic behavior, by bottom-spraying polymeric suspensions on a spouted bed of inert particles. Glass beads, ABS®, polypropylene (PP), and polystyrene (PS) were chosen as inert particles and were analyzed and characterized by their physicochemical properties. The polymeric suspensions were characterized by density, surface tension, rheology, and wettability. The fluid dynamic behavior of the bed was correlated with the particles and suspensions characteristics for each process: coating and drying. Each process performance was correlated with the polymeric suspension-particle work of adhesion.     

基于接触角方法沥青与石料粘附特性及路用性能研究

沥青-石料粘附失效产生的病害,如松散、脱粒、麻面、坑槽等,致使沥青路面使用性能下降,危及行车安全,基于表面自由能理论的躺滴法作为接触角法中评价沥青-石料粘附性的试验方法,因其操作简单、定量评价、人为误差小等特点,成为了近年来研究评价沥青-石料粘附性的热点.本文采用躺滴法,以西北地区三种品牌沥青与甘肃省七种石料作为研究对象,利用水煮法、躺滴法评价沥青-石料粘附性与AASHTO T283评价沥青混合料水稳定性进行对比分析,结果表明,水煮法定性评价沥青-石料粘附等级、接触角法定量评价沥青-石料粘附功与AASHTO T283评价沥青混合料水稳定性的冻融劈裂强度比(TSR)的决定系数分别为0.1956、0.2731、0.4793,0.8179、0.7173、0.7997,说明接触角法粘附功定量评价沥青-石料粘附性能够较为准确的评价沥青混合料水稳定性;同时三种沥青的粘附能力依次为C＞B≥A,七种石料的粘附能力依次为平凉上杨石灰岩＞玉石湾蛇纹岩＞黑山湖玄武岩＞东乐石灰岩＞永登玄武岩＞出卜拉沟玄武岩＞定西花岗岩.     

口型入口角对HIPS熔体流动行为的影响

选用一组具有不同入口角的毛细管口型,考察了挤出过程中入口角(2α)对HIPS熔体流动行为的影响,实验结果表明,熔体的流动基本上服从幂律,其表观剪切粘度对温度的依赖性大致上符合Arrhenius方程,其值随着2α的不同有所改变。试样的末端效应相当明显,末端压力损失随着2α的增加而减小,并于2α=75°处出现极小值。     

羧甲基纤维素钠对表面张力和接触角的影响

本文利用各种样品的表面张力和接触角的实验数据，说明羧甲基纤维素钠对洗涤作用的影响。     

The Effect of Drop (Bubble) Size on Contact Angle at Solid Surfaces

Examples of experimental contact angle data for varying drop and bubble volumes on different solids whose surfaces are smooth and homogeneous, rough and homogeneous, smooth and heterogeneous, and covered with unstable organic films are presented. The ideas and theoretical models as proposed in the literature for the interpretation of contact angle/drop (bubble) size relationships are critically reviewed. It is shown that major factors affecting the contact angle variation with drop (bubble) size such as surface heterogeneity, roughness, and stability, have been identified in the literature. However, there is still a need for experimental work with well-defined and well-characterized solid surfaces. Theoretical models that have been proposed in the literature are still inadequate. Advanced modeling of liquid behavior at heterogeneous and rough surfaces is required to understand further, and to predict, the contact angle/drop (bubble) size relationships at imperfect surfaces.     

The Effect of Drop (Bubble) Size on Contact Angle at Solid Surfaces

Examples of experimental contact angle data for varying drop and bubble volumes on different solids whose surfaces are smooth and homogeneous, rough and homogeneous, smooth and heterogeneous, and covered with unstable organic films are presented. The ideas and theoretical models as proposed in the literature for the interpretation of contact angle/drop (bubble) size relationships are critically reviewed. It is shown that major factors affecting the contact angle variation with drop (bubble) size such as surface heterogeneity, roughness, and stability, have been identified in the literature. However, there is still a need for experimental work with well-defined and well-characterized solid surfaces. Theoretical models that have been proposed in the literature are still inadequate. Advanced modeling of liquid behavior at heterogeneous and rough surfaces is required to understand further, and to predict, the contact angle/drop (bubble) size relationships at imperfect surfaces.     

Contact angle of surfactant solutions on precipitated surfactant surfaces

In this study, the contact angle of a saturated aqueous surfactant solution onto the surface of a precipitate of that surfactant is investigated. Those precipitates include fatty acids (C₁₀, C₁₂, C₁₄, C₁₆, and C₁₈), sodium salts of fatty acids (C₁₄, C₁₆, and C₁₈), calcium salts of fatty acids (C₈, C₁₀, C₁₂, C₁₄, C₁₆, and C₁₈). On virgin surfaces, free fatty acids and calcium salts of fatty acids have advancing contact angles (θ_A) between 77 and 92°, with little dependence on alkyl chain length for C₁₂ and higher alkyl chains. The sodium salt of a fatty acid has a lower θ_A than the free fatty or the calcium salt of the soap. The calcium salt of dodecyl sulfate has a lower θ_A than the calcium salt of dodecanoic acid (θ_A = 46 vs. 82°), but the calcium salt of the 18-carbon hydrophobes showed nearly the same contact angle for the soap and the alkyl sulfate. Greasiness, or slipperyness, or a scummy feel of a precipitated surfactant does not necessarily correspond to a hydrophobic surface.