Theory for the decay of the wet shear strength of adhesion and its application to metal/ epoxy/ metal joints

A theory for the decay of the wet shear strength of adhesion has been produced by formalizing the quantitative relationship between wet shear strength of adhesion and moisture content. Theoretical values for the retention of wet shear strength of adhesion with time coincided with experimental data. It has been clarified that the diffusion coefficient of water is larger at the interface than in the adhesives, and that moisture absorption is determined by the diffusion of water at the interface.     

Iron Oxide-Coated on Glass Fibers for Arsenic Removal

A highly efficient adsorbent for arsenic removal from water has been prepared by impregnating high surface area iron oxides on glass fibers. Arsenic in water can easily and efficiently be removed by this adsorbent, without the need to pre-oxidize As(III) to As(V). The iron oxides coated on glass fibers (IOCGFs) can remove both arsenic species well below EPA MCL (10 ppb). IOCGFs should have the following four additional advantages: greatly improved contact efficiency; higher adsorption capacity because of high surface area; low cost and easily available adsorbent since the starting reagents (FeCl₃ and NH₃·H₂O) and glass fiber are cheap and readily available; and high adsorption efficiency of As(III) and As(V).     

新型除臭涂料的研制和应用

将铜、铁、钴、钼、锌等过渡金属氧化物,铈等稀土金属氧化物,以及钯等稀有金属氧化物为主要活性组分,吸附于高岭土等多孔性矿物质上,配以无机－有机复合基料,制成涂料,涂覆于玻璃管上,形成除臭效果及附着力良好的催化除臭涂层。     

陶瓷坯体中氧化铁红的呈色稳定性及其影响因素的研究

本文考察了烧成温度、陶瓷坯体中常见氧化物,以及二氧化硅包裹对铁红呈色稳定性的影响。结果表明,陶瓷坯体中铁红的呈色主要受四种因素影响：（１）温度,高温下铁红本身不稳定,易失氧而成黑色四氧化三铁,因此对呈色不利;（２）陶瓷坯体中某些活泼成分（如氧化钙等）,高温下易与铁红反应生成其它颜色的物质,因此对呈色不利;（３）陶瓷坯体中另一些活泼成分（如氧化镁等）,高温下也易与铁红反应,但生成物较稳定且接近红色,     

Einfluß der Faserbehandlung auf das Feuchteverhalten von glasfaserverstärkten Epoxidharzen

The strength of glass fiber reinforced epoxy resins can be significantly reduced under exposure to moisture. Besides other factors, the interface between fiber and matrix plays an important role. It is responsible for a proper load transfer between fibers and matrix by coupling effects and significantly affects the moisture behavior of the composite. In the present study, glass fibers were treated with different sizes under defined conditions and embedded in three epoxy matrix systems. The composites were exposed to different moisture conditions. The change of the shear and impact behavior due to moisture was determined. It will be shown that the composites with coupling agent treated fibers are significantly more resistant to moisture than composites with poor fiber/matrix adhesion. Furthermore, it will be shown that also the binder plays an important role if the material is subjected to moisture.     

Effect of material composition on antistripping performance of SBS modified asphalt mixture under dry and wet conditions

Styrene-butadiene-styrene (SBS) modified asphalt used in road engineering is a complicated mixture of various compositions. The present study was undertaken to evaluate the influence of different raw materials and their content on the moisture stability of SBS copolymer modified asphalt mixture. A total of 18 different combinations of base asphalt, SBS, furfural extract oil (FEO), and stabilizer were considered to prepare different SBS modified asphalt samples, and the contact angle test was carried out to determine the work of adhesion and the work of debonding of SBS modified asphalt with aggregate. Moreover, a multi-factor Analysis of Variance (ANOVA) was conducted to investigate the statistical effects of the material composition factors. The results show that the bond strength between SBS modified asphalt and aggregate is significantly affected by the source of base asphalt, but it is insensitive to the change of SBS type under dry and wet conditions. Besides, the moisture damage resistance of SBS modified asphalt improves firstly and then reduces with the rising storage of SBS, FEO, and stabilizer. Furthermore, linear regression analysis suggests that the work of adhesion under dry condition has excellent correlation with the work of debonding under wet condition.     

固化废弃软黏土的强度特性及水稳定性研究

为了提高水泥和粉煤灰固化高含水率废弃软黏土的固化效果,选取水玻璃作为外加剂,吸水性强的生石灰作为分散剂,采用无侧限抗压强度试验、X 射线衍射、扫描电镜试验研究掺量与龄期对固化软黏土水稳定性和强度特性的影响。试验结果表明,3%(质量分数)的水泥、7%(质量分数)的粉煤灰、2%(质量分数)的生石灰与2%(质量分数)的水玻璃复合时能较好提高高含水率软黏土固化后的强度和水稳定性,其强度能达到水泥粉煤灰类基底层最低强度(1 MPa)。在水泥、粉煤灰和水玻璃质量掺量相同情况下,生石灰质量掺入比由0%增加至2%,其强度增大约375 kPa,且有利于后续固化剂的均匀搅拌,说明生石灰的减水和分散效应在固化土中起主导作用。此外,扫描电镜结果显示加入复合固化剂后大集聚体消失,产生大量的片状结构,大孔隙被填充,土体的强度也随之提高。     

Weathering of polypropylene composites containing weldlines

Abstract

This work deals with the weathering behaviour of polypropylene composites containing fillers with various aspect ratios (glass fibre, talc, and calcium carbonate). Single and double end gated injection moulded bars were exposed outdoors in Campina Grande (Brazil) for periods up to 45 weeks and then characterised using infrared spectroscopy, tensile testing, and surface fractography. The unfilled polymer displayed the highest level of mechanical deterioration, followed by polypropylene containing glass fibre, whereas compounds with talc and calcium carbonate were the most resistant to photodegradation. These results are partially a consequence of the screening effect caused by talc and calcium carbonate at the exposed surface. The results indicated that weldlines make the parts weaker, although the strength loss caused by weathering of double end gated samples was similar to that observed with mouldings produced by single gated injection. It was also observed that the adhesion between glass fibre and the polymer matrix was much reduced after weathering, probably as a result of diffusion of water to the interface.     

Quantitative evaluation of active based adhesion in Aggregate-Asphalt by digital image analysis

Moisture damage has become one of serious distresses to reduce stability of pavement structure and service life. One of the most essential reasons for moisture damage is insufficient adhesion between asphalt and aggregate. Most conventional methods for evaluating adhesive characteristic are subjective and empirical and adhesion results are seriously affected by tester's operation habit and judgment. Meanwhile, active adhesion mechanism was not considered in most conventional methods. This study designed an active adhesion based test method, named active adhesion evaluation method (AAEM), to make up for the lack of research on active adhesion and eliminate the subjective operation in boiling process. Boiling water test was performed on basalt and steel slag aggregates for comparison with AAEM. Digital image processing was used for quantitative detection of adhesive characteristic. Results show that digital image processing can accurately and effectively measure asphalt coating ratio. Mixing time of 90?s, and asphalt content of 2.5% were finally selected as the optimum AAEM test parameters. The variance and standard deviation of coating ratios of AAEM are much smaller than that of boiling water, whether it is steel slag or basalt, indicating that the AAEM is indeed an effective method for measuring coating ratios of aggregates. The distinction of coating ratios for basalt and steel slag can be amplified by AAEM compared with boiling method.     

Mechanical characterization of epoxy moulding compound in pressurized steam

Epoxy Molding Compounds (EMCs), commonly based on epoxy resin, are used widely for encapsulation of chips in electronic devices for protection against mechanical, environmental, and chemical attack. The thermo-mechanical properties of these compounds are important for the assessment of package reliability. These properties are highly dependent on the temperature and moisture.EMCs absorb water when exposed to a humid environment. The trapped water generates steam in the compounds during the soldering reflow part of the packaging assembly process, which may drastically change the viscoelastic and adhesion behavior of the compound.The present research focuses on the characterization of mechanical properties of an epoxy molding compound in steam at elevated pressure (temperature above 100 °C and relative humidity equal to 100%). A special steam chamber with a highly accurate tensile setup for force and displacement measurements is designed and manufactured. The chamber is equipped with a 3 Point Bending (3PB) loading setup. The setup can also be modified to mixed mode bending for investigating the effect of temperature and steam on the molding compound-to-lead frame interface strength.In this paper, the viscoelastic creep compliance of a molding compound in dry and wet environment is measured in 3 point bending mode. It is shown that steam significantly affects the thermo-mechanical properties of the molding compound. The glassy and rubbery modulus of the molding compound were seen to decrease almost by 20%. Furthermore the glass transition temperature decreased by about 30 °C and the creep process was seen to be about a factor 40 faster in a hot steam environment.     

金属氧化物增强封接玻璃的研究

依据封接的物理相容性与化学相容性,制备了两种添加有微量金属氧化物的改性DM-308型电子玻璃,研究了添加的金属氧化物对玻璃与可伐合金结合性能的影响.结果表明:添加微量的金属氧化物可以不同程度地提高玻璃与可伐合金的结合强度;非界面处玻璃中气孔率的降低以及玻璃化学键键性的改变是增强的主要机理.     

THE WEATHERING OF GLASS CONTAINERS1

Stability in storage is a requisite of commercial glass. A white film or surface spotted with white patches is frequently observed on glass that has been in storage for some time. These weathering effects can be produced artificially by several methods which are given. Several factors, including humidity, have been found to influence the rate at which weathering takes place. Dipping in hydrochloric acid before packing retards weathering and paper properly used in packing is effective in decreasing the tendency to weather. Three classes of weathering effects are given and illustrated with microphotographs. Experiments show that continued boiling removes the weathered surface. The products of weathering consist of crystals of soluble salt or salts, principally sodium carbonate, and an insoluble film. The lime, soda, and silica are found to have the same relative values in the weathered material as in the original glass, with the addition of certain amounts of carbonate, moisture, and dirt and organic material. Weathering is largely dependent on solubility. Glass showing the greatest resistance to weathering proves equally resistant to action of water at temperatures and pressures above normal. Condition of surface appears to influence the solubility. Alumina increases the resistance of glass to weathering. Sodium carbonate may exist in glass after manufacture and assist in weathering.     

水热法制备纳米氧化铁的研究

对水热法制备纳米氧化铁以及氧化氢氧化铁进行了研究。通过实验制得了多种不同形貌的纳米氧化铁以及纳米氧化氢氧化铁,利用X射线电子衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)对所得产物进行了表征,研究了反应时间、温度对最终产物形貌、粒径的影响,对产物的变化规律进行了总结。     

Effect of Surface Energetics of Substrates on Adhesion Characteristics of Poly (p-xylylenes)

In investigating the effect of the surface energetics of substrate materials on the adhesion characteristics of poly(p-xylylene) and poly(chloro-p-xylylene) by the “Scotch Tape” method, it was found that if the substrates had not been preconditioned (treated with argon or a methane plasma), the adhesion was poor. The characteristics of water resistant adhesion that were observed when coated substrates were boiled in 0.9% sodium chloride solution were found to vary from excellent (when the polymer did not peel from the substrate after three cycles of 8 hours of boiling and 16 hours at room temperature) to poor (when the polymer peeled off almost immediately). It was noticed that water resistant adhesion depends on the hydrophobicity of the substrate material (the greater the hydrophobicity, the greater the adhesion) and is not related to the dry adhesive strength of poly(p-xylylene). The oxygen glow discharge treatment of the substrates decreased both the dry and wet adhesive strength of the polymer. The effect of the argon glow discharge treatment depended on the surface energetics of the substrate, and the methane glow discharge treatment increased both the dry and wet adhesive strength of the polymer. These preconditioning processes are discussed in terms of the sputtering of the material from the wall of the reactor in contact with the plasma and the deposition of the plasma polymer of the sputtered material on the substrate surface.     

多胺活性剂对沥青抗剥落效力研究

研究了SBS对石油沥青的改性及多胺活性剂aa对沥青的抗剥落效力.用水煮法对水浸石料颗粒与干燥石料颗粒与基质沥青或改性沥青的粘附性能分别进行了考查,SBS改性沥青材料添加0.3?后裹覆干燥石料颗粒,耐水煮时间延长 9 min以上;添加0.3?的基质沥青材料裹覆浸水石料颗粒的耐水煮时间与不添加aa的基质沥青材料裹覆干燥石料颗粒的耐水煮时间相同.     

Blending poly(2-ethyl-2-oxazoline) with hydrophobic polymers as a hybrid adhesive with enhanced water-resistant properties

The use of poly(2-ethyl-2-oxazoline) (PEOX) in a wet environment is limited because of its high hydrophilicity. In this study, PEOX based blends were prepared via blending PEOX with hydrophobic polymers, such as poly(styrene-co-acrylonitrile) (SAN), poly(4-vinylphenol) (PVPh), and poly(vinylidene fluoride) (PVDF), in order to improve the water-resistance of PEOX. The blends' water resistance properties are evaluated by the contact angle, solubility, moisture absorption, and mechanical strength in a wet environment. The results show that the water resistance and the adhesion strength of PEOX in a wet environment are dramatically enhanced by polymer blending. The blend with 30 wt% PVPh demonstrates excellent performances in transparency and water-resistant abilities. It is found that the stable hydrogen bonding within the blend plays an important role in hydrophobic modification. The PVPh/PEOX blend can be applied as a new type of transparent coating or adhesive with enhanced water-resistant properties in a wet environment.     

Fluoride Ions Behavior in the Presence of Corrosion Products of Iron: Effects of Other Anions

The behavior of fluoride ions in the presence of corrosion products of iron in drinking and water solutions was analyzed and the adsorption capacities of the iron oxides (corrosion products of iron) for fluoride ions were determined. Drinking water containing naturally 2.45 mg of fluoride ions per liter was characterized and the concentrations of other anions were determined. The effect of contact time, the initial concentration of fluoride ions, and the effect of other anions naturally present in the drinking water were considered. The kinetic results could be adjusted to the pseudo-second order model, which indicated that the sorption mechanism was chemisorption and the equilibrium was reached in 24 hours. The presence of bicarbonate and chloride ions diminishes the removal efficiency of the fluoride ions, whereas other anions (sulfate, phosphate, and nitrate) did not show any significant effect. The results reflect that the iron oxides products from the corrosion of a hydraulic infrastructure allow the removal of fluoride ions from water.     

Imaging in evaluation of polymer coatings adhesion to glass at high humidity

Adhesion reduction occurring after polymer coated glass was immersed in water was studied in a variety of UV-cured urethane acrylate coatings containing alkyloxysilane adhesion promoting additives. It was observed that water accumulated under the coating surface in drops and formed ‘blisters’ in the glass-polymer interface. A non-destructive imaging technique was developed to measure the average size of the water blisters. The size of the water blisters within the interface was correlated with the wet adhesion force measured by coating resistance to 180° peel. The force of coating resistance to 180° peel off glass surface decreased non-linearly with the increase of the average size of the water blisters. It was concluded that the decrease in adhesion between the coating and glass was a result of stretching and breaking of the silane bridging bonds and polymer fibrils by water condensing on the glass surface within the polymer-glass interface. The mathematical model relating coating wet peel resistance force with the size of the debonding produced by water accumulation was presented.     

石灰沉降法对含铁、铜废水的处理

研究了石灰乳絮凝沉降法同时去除废水中铁和铜。实验研究了不同操作变量,如溶液pH值,石灰的配比,反应时间等对铁和铜（主要是铁）的去除率的影响。在适宜的操作条件下,废水中的铁和铜去除率高达99%,处理后残液中铁的浓度小于3 mg/L,铜的浓度为0.3 mg/L。     

新型无铬高变催化剂的研究开发

根据铁铬系高温变换催化剂的催化机理，对钙钛石型稀土铁复合氧化物高温变换催化剂进行了设计和制备。采用XRD、活性评价等实验技术对模型催化剂进行了测试，结果表明,钙钛石型混合稀土铁复合氧化物具有较好的高温变换催化活性，以La_0.5Ce_0.5FeO₃·K的催化活性最好，CO的转化率可达72%，其热稳定性也较好，能与传统的铁铬系催化剂相媲美，是一种具有工业开发价值的无铬高温变换催化剂。