纳米炭纤维的表面润湿行为

采用动态渗透法研究了不同结构的纳米炭纤维(Carbonnanofibers,CNF)表面润湿性以及在不同溶剂中润湿性的变化和表面改性对其润湿性的影响。结果表明,生长条件如催化剂组成、碳源等对CNF的表面性质有显著影响,并最终决定其在溶剂中的润湿能力。以Fe/γ-Al2O3为催化剂,以C2H4为碳源得到的CNF在水中的润湿性能最差;而以Ni/γ-Al2O3为催化剂,CO为碳源得到的CNF在环己烷中的润湿性能最好。CNF在不同溶剂中的相对接触角测定表明CNF是一种表面非极性较强的材料。设CNF在润湿性能最好的环己烷中的接触角为0°,则CNF在水,丙酮,乙醇中的相对接触角分别为81.6°,45.2°,24.8°。不同的表面改性手段可对CNF的表面性质进行调变以控制其在不同溶剂中的润湿行为。在浓硝酸中液相氧化可提高其对水溶液和环己烷的润湿性能;在氩气中的高温热处理可提高其对水溶液的润湿性能,但降低了对环己烷的润湿能力;而在过氧化氢溶液中的处理则同时降低了对水溶液以及环己烷的润湿能力。     

单一玻璃纤维/树脂润湿过程分析及动态接触角的Wilhelmy法测量

基于Wilhelmy法,组建了纤维/树脂动态润湿测量系统,研究了单一玻璃纤维/树脂的动态接触角测量方法,分析了润湿过程及其特征。结果表明,单一ECT玻璃纤维/CYD128环氧树脂润湿体系为混合润湿,其动态接触角的适宜测量参数为:浸入速度0.03mm/s,检测阈值0.08mg,浸入深度1.5mm。     

西南桦木包装材料在热处理后的润湿性能研究

通过动态接触角测量、红外光谱分析、表面粗糙度测量、扫描电镜观察和偏相关分析,研究了西南桦木的润湿性能。结果表明,木材经180℃热处理4 h后,润湿性能下降:接触角由40°增至121°,羟基和羰基数量减少,粗糙度降低;处理时间与接触角显著相关;西南桦木用作包装材料,若采用热处理,可去除有害生物,还具备疏水功能。     

不同立杆高度毛竹材弦切面的润湿性能研究

本文研究了H2O、酚醛树脂胶黏剂(PF)、脲醛树脂胶黏剂(UF)和改性大豆蛋白胶(MSA)在毛竹材不同立杆高度弦切面的润湿性能,通过测定这些润湿液体在竹材弦切面上的接触角,建立润湿液体在毛竹材弦切面的动态润湿模型,分析毛竹材的不同高度对润湿液体动态润湿性能的影响,并对比分析各种润湿液体在毛竹材弦切面的润湿性能差异。     

氧离子束工作压强对PET表面化学键结构及润湿性能的影响

利用直流离子源产生氧离子束并在室温条件下与PET表面进行相互作用.通过X光电子能谱仪、接触角测试仪等表征技术,分析氧离子束工作压强对PET表面化学组分、化学键结构,以及对极性H2O分子液体的静态接触角等性能的影响.研究结果表明,当氧离子束与PET表面相互作用时,PET表面的C-O、C-H键首先被破坏,氧离子与C-垂悬键结合形成C-O或C=O极性键.随着氧离子束工作压强的增加,更多的氧离子与PET表面相互作用,导致处理后的PET表面含氧量增加,C=O/C-O比例增加,对极性H2O分子液体侵润性增强.当氧离子束工作压强增加至0.9Pa时,处理后的PET表面氧元素相对百分比含量由纯PET的28％增加至37％(原子比),C=O/C-O键比例由纯PET的1.13∶1增加至2.85:1,而极性H2O分子液体的静态接触角由纯PET的55.3°减低至7.0°,接近于完全润湿.上述结果表明,氧离子束是一种有效调节PET表面化学组分、化学键结构、及表面性质的简单而有效的方法.     

碳纤维与环氧树脂润湿和黏附作用

对比分析了不同类型碳纤维与环氧树脂的接触角的变化规律, 并利用Young-Dupre法和Wu法, 分析了黏附功随温度的变化规律, 以及树脂固化对纤维/树脂润湿、黏附作用的影响。结果表明: 升高温度有利于T300、CCF、T700纤维和环氧AG80树脂的润湿, 去除纤维表面上浆剂后其表面能极性分量下降, 与AG80树脂的润湿和黏附性能变差; 在树脂体系未发生化学反应前, AG80/DDS树脂体系比AG80纯树脂与T700纤维的润湿性能好, 黏附性能差; 110 ℃恒温条件下随固化时间延长, AG80/DDS和E51/DDS树脂体系与T700纤维的浸润和黏附性能均改善。      

硅烷偶联剂对玻璃纤维表面性能的影响

固体的表面自由能是影响到吸收,浸润,粘附等表面性能的一个特征因子,但测定固体表面能的直接方法尚未建立。在本研究中,我们采用电子天秤法对未处理玻璃纤维及各种硅烷偶联剂处理后玻纤的表面自由能及其分量作了测定,其基础是通过测定液体L₁在另一液体L₂之下对固体S接触角,间接地求得固体的表面能。结果表明,玻纤的表面自由能因硅烷偶联剂的处理而降低,并与偶联剂的结构密切有关。若硅烷中带有极性基团,则处理后玻纤的表面能较高;反之若硅烷中不含有极性基,则处理后玻纤的表面能较低。用带双键硅烷处理的玻纤有中等的表面自由能。      

阳极氧化铝合金-环氧树脂动态润湿行为

对铝合金板材进行了磷酸阳极化表面处理,采用电子显微镜观察了铝合金表面形貌,采用量重法测试了铝合金/环氧树脂动态接触角,研究分析了阳极化电压与时间、浸润速度等对铝合金/环氧树脂动态润湿行为的影响。结果表明,氧化电压保持20 V不变,随着氧化时间延长,动态接触角先大幅减小然后缓慢增加;氧化时间保持20 min不变,随着氧化电压上升,动态接触角先减小后增加;阳极氧化工艺参数20 V/30min处理的铝合金板具有最小前进接触角68.63°与后退接触角10.22°,相比未处理铝合金/环氧树脂前进与后退接触角分别减小18.89和25.1°;增加铝合金浸入树脂的速度,接触角增大。     

壳聚糖膜表面的氮等离子体改性研究

采用溶液浇铸法制备了壳聚糖膜,通过氮等离子体对壳聚糖膜进行表面改性以提高其表面亲水性。采用扫描电子显微镜（SEM）、表面接触角分析仪和X射线光电子能谱（XPS）对改性前后壳聚糖膜的表面结构和性能进行分析和表征,研究了不同等离子体处理时间和不同放电功率对壳聚糖膜表面结构和性能的影响。结果表明：经氮等离子体处理后,壳聚糖膜的表面接触角可由103．0°降为48．8°,表面亲水性得到明显改善。由XPS分析得知,膜表面的氧、氮含量及氧碳比增加,表面的C-C键发生了断裂而生成新的〉C=O（COOR、C00H或cONH）等极性基团,从而使其亲水性增强。     

液态树脂基材料与铜基材料的界面润湿现象分析

采用静滴法观察了液态树脂基材料与铜基材料的界面润湿现象,测定了298～363 K温度范围内的接触角,计算了附着功.结果表明:接触角随时间呈下降趋势,基板表面粗糙度对接触角的影响较大,在表面粗糙度较小时,接触角随时间下降较快,平衡接触角较小;初始接触角和平衡接触角均随树脂基材料中环氧树脂含量的增加而降低;升高温度使接触角的变化速率加快,加入树脂后的液体的平衡接触角对温度更加敏感;附着功随着时间的延长逐渐增加,但随着温度的上升而减小.     

Influence of fluorinated self-assembled monolayer on wetting dynamics during evaporation of refrigerant–oil mixture on metal surface

Reducing wettability of a metal surface is a promising method for enhancing boiling heat transfer of refrigerant–oil mixture on the metal. As fluorinated self-assembled monolayer (F-SAM) coating is effective for wettability reduction, its influence on wetting dynamics including meniscus shape, contact angle, contact line velocity and rising liquid height during evaporation of refrigerant–oil mixture on metal surface were experimentally investigated. The refrigerant–oil mixture was prepared by R141b and NM56, the oil mass fraction ranged from 0 to 10 wt%, and the surface roughness ranged from 0.028 to 1.166 µm. The results show that during evaporation of refrigerant–oil mixture, the presence of F-SAM changes the evaporation mode to be constant contact line velocity followed by both constant contact angle and contact line velocity, while decreases the rising liquid height. The results suggest that larger surface roughness and higher oil mass fraction are preferred when using F-SAM to reduce surface wettability.     

动态毛吸法测定纤维及粉末料的接触角研究

本文用动态毛吸法研究了表面处理对纤维浸润性的影响,结果表明碳纤维及聚酯纤维表面经冷等离子体氧处理,浸润性有很大的改善,碳纤维约提高四倍,这是因为等离子氧表面处理过程,将含氧基团羧基,羟基及羰基等引入到表面所致。同时从测得的浸润过程表面自由能改变值△γ,计算出水对纤维的接触角,它与采用接触角测定仪倾斜法所测得的结果基本上一致。从所测得的接触角值也可以看出表面经处理之后,浸润性得以改善。如碳纤维由77°降为63°,聚酯纤维由77°降为52°。此外我们还研究了煤粉和玻璃粉体系对水的浸润性,发现水对玻璃粉的浸润性优于煤粉,前者的浸润接触角为47°、后者则为90°,此接触角值也与采用接触角测定仪由静滴法测得水对片材的接触角相一致。由此可见动态毛吸法可以用于研究纤维及粉末体系的浸润性,而且操作简单易行,测试周期短。      

The effect of substrate surface roughness on the wettability of Sn-Bi solders

The effect of substrate surface roughness on the wettability of Sn-Bi solders is investigated by the eutectic Sn-Bi alloy on Cu/Al₂O₃ substrates at 190 °C. To engineer the surface with different roughnesses, the Cu-side of the substrates is polished with sandpaper with abrasive number 100, 240, 400, 600, 800, 1200, and 1 m alumina powder, respectively. Both dynamic and static contact angles of the solder drops are studied by the real-time image in a dynamic contact angle analyzer system (FTA200). During dynamic wetting, the wetting velocity of the solder drop decreases for the rougher surface. However, the time to reach the static contact angle seems to be identical with different substrate surface roughness. The wetting tip of the solder cap exhibits a waveform on the rough surface, indicating that the liquid drop tends to flow along the valley. As the solder drops reach a static state, the static contact angle increases with the substrate surface roughness. This demonstrates that the wettability of solders degrades as the substrates become rough.     

环氧树脂-固化剂混合液体与铜基材料的润湿性能研究

采用静滴法观察了液态纯固化剂和20%树脂-80%固化剂混合液体与铜基材料的润湿行为,测定了298～363K温度范围内的接触角,评价了两种液体与铜基材料的润湿性.结果表明,接触角随时间呈下降趋势,初始接触角随着试样中环氧树脂比例的增加而降低,温度对固化剂平衡接触角的影响较小.在同样的温度条件下,加入树脂后的液体的平衡接触角小于纯固化剂的平衡接触角.     

碳纤维表面性能的研究

通过此表面、接触角、浸润性、表面能和表面基团的测定,本文较系统地研究了碳纤维表面性能。结果表明经处理后的碳纤维表面的浸润性、此表面、表面能与表面基团含量都增加。就浸润性而论,不论对环氧或水的接触角都随氧化处理时间增加而减少,浸润速度随氧化处理而上升,表面能随氧化处理而提高。特别是表面能中极性组份增加得较为显著,这与表面基团分折结果表明表面含氧极性基团随氧化时间增加而增加的结论是相一致的。另外表面基团含量化学分析的结果与XPS分析的结果基本上一致,因此可以用XPS表面基团分析来代替烦杂的化学分析方法。      

原位聚合液晶环氧改性环氧树脂的研究

研究了原位聚合PHBHQ对环氧树脂的改性作用，结果表明，随着PHBHQ含量的增加，环氧树脂的冲击强度明显得到提高，而其他性能也不同程度的改善，并采用SEM分析了PHBHQ／CYD－128复合体系的微观结构。     

The effects of solder deformation on the wetting characteristics and interfacial reaction of Sn–3.5Ag solders on Cu substrates in fluxless soldering

The effects of solder deformation on the wetting characteristics during fluxless soldering were studied when deformed Sn–3.5Ag solder balls were reacted with Cu or oxidized Cu substrates. The Cu surfaces were oxidized at 100 °C for 2 or 4 h in air. After the 760 μm diameter solder balls were deformed on the substrates under 0–30 N, they were then reflowed at 300 °C for 30 s without flux. An optical microscope and a scanning electron microscope equipped with energy dispersive spectroscopy were used to measure the wetting angles and to characterize interfacial microstructures. As solder deformation increased, the wetting angle of solder bumps on the Cu or oxidized Cu substrates decreased and the spreading area increased. The oxide layer on the Cu surface decreased the wettability of the solders. Intermetallic compound (IMC) growth was suppressed in the solder interface when the solder reacted with oxidized Cu, while the IMC thickness increased with solder deformation. Solder deformation exposed a fresh Sn surface and improved contact between the solder and Cu substrate, thereby increasing the wettability of the solders.     

Bitumen spreading on calcareous aggregates at high temperature

In hot asphalt applications, the adhesion between bitumen and mineral aggregate is usually described in terms of bitumen surface tension and contact angle of the bitumen over the aggregate. However, the quantification of the physico-chemical bond between bitumen and aggregate under realistic conditions is a nontrivial task. In this work, we designed a high-temperature goniometer to measure the contact angle of liquid bitumen on mineral aggregate substrates. The drop deposition was conducted once the thermal equilibrium between liquid bitumen and aggregate was attained. We monitored the spreading of sessile drops of viscous naphthenic bitumen and asphaltic bitumen on polished sheets of calcareous aggregates at high temperature (70–100 °C). A near complete wetting with very low contact angles (13– \(24^{\circ }\) ) was reproduced regardless of the bitumen origin and temperature. Furthermore, the coating degree of the naphthenic and asphaltic bitumens on the calcareous aggregates at high temperature was apparently similar. We found that the bitumen-aggregate adhesion is adequately described by dynamic spreading rather than by equilibrium wettability. Spreading kinetics was ruled by the particular properties of each bitumen such as viscosity and acid index. We found evidences of acid etching of the naphthenic bitumen on the calcareous aggregates during spreading at high temperature.     

Hyperhydrophilic rough surfaces and imaginary contact angles

The complete wetting of rough surfaces is only poorly understood, since the underlying phenomena can neither be described by the Cassie‐Baxter nor the Wenzel equation. An experimental accessiblility by the sessile drop method is also very limited. The term “superhydrophilicity” was an attempt to understand the wetting of rough surfaces, but a clear definition is still forthcoming, mainly because non‐superhydrophilic surfaces can also display a contact angle of zero. Since the Wilhelmy balance is based on force measurements, it offers a technology for obtaining signals during the whole wetting process. We have obtained evidence that additional forces occur during the complete wetting of rough surfaces and that mathematically contact angles for a hydrophilicity beyond the contact angle of zero can be defined by imaginary numbers. A hydrophilized TPS‐surface obtained by chemical wettability switching from a superhydrophobic surface has been previously characterized by dynamic imaginary contact angles of 20i°–21i° and near‐zero hysteresis. Here an extremely high wetting rate is demonstrated reaching a virtual imaginary contact angle of Θ_V,Adv > 3.5i° in less than 210 ms. For a rough surface displaying imaginary contact angles and extremely high wetting rates we suggest the term hyperhydrophilicity. Although, as will be shown, the physical basis of imaginary contact angles is still unclear, they significantly expand our methodology, the range of wettability measurements and the tools for analyzing rough hydrophilic surfaces. They may also form the basis for a new generation of rationally constructed medicinal surfaces.