Experimental Investigation of Epoxy Bonded Polymethylmethacrylate Joints

This paper presents an experimental investigation into various aspects of epoxy-bonded polymethylmethacrylate (PMMA) and PMMA-to-aluminium joints. The effects of adhesive thickness, overlap area, surface roughness, and environmental exposure on the joint strength were studied. Results indicated that the joint strength was not directly proportional to the overlap area, while sanding had a positive effect on the joint strength. A negative effect was observed when adhesive thickness was increased. The fatigue behaviour of adhesively-bonded joints under dynamic loading was found to be independent of frequency, for the range of values tested; however, it was dependent on the test temperature with greater reduction in fatigue life observed in PMMA-to-aluminium joints at higher temperature. Empirical equations from which the fatigue life of joints can be predicted were obtained by regression analysis. Intermittent fatigue testing of the joints was also performed. The epoxy adhesive tested proved to be a satisfactory choice for outdoor exposure. The rate of degradation of the adhesive was slow with the adherend itself degrading at a faster rate than the adhesive or the bondline.     

BOPP珠光膜及其生产工艺

详细介绍了BOPP珠光膜的特性和生产工艺,特别指出了BOPP珠光膜生产中的难点和排除方法,对实际生产有相当的价值.     

多层水平气流带式干燥机的数学模型

根据干燥传质传热学原理和干燥动力学特性，建立了水平气流带式干燥机干燥过程的数学模型。该模型可以预测干燥机合理的通风道高度、带翻转最佳时间和热风风速等。为优化多层带式干燥机的结构或设计新的水平气流带式干燥机提供了理论依据。     

Shear-induced interactions in blends of HMMPE containing a small amount of thermotropic copolyester HBA/HQ/SA

Shear-induced interactions between high molecular mass polyethylene (HMMPE) melt and a thermotropic liquid crystalline copolyester, HBA/HQ/SA (TLCP) were investigated using large amplitude oscillatory shear and capillary shear. Polarized optical microscopy (POM) observations show that the mono-domain nematic TLCP droplets embedded inside a HMMPE melt may be readily elongated using large amplitude oscillatory shear. The HMMPE melt adjacent to the elongated TLCP filament was observed to crystallize faster than that in the matrix away from the interface. TEM analysis on the 1 wt% TLCP/HMMPE blend quenched after capillary shear shows that there are strong interfacial interactions between the elongated TLCP filament and the HMMPE matrix. Long range PE lamellae orientational order up to 2 μm away from the TLCP filament surface were observed, with all the lamellae surface normal parallel to the TLCP fiber. Additionally, a strong interfacial compatibility between the TLCP filament and the HMMPE matrix with an interfacial thickness of ∼30 nm has also been observed. The enhanced interfacial compatibility is attributed to the -CH₂- group interactions due to chain alignment in both components at their interface. These results provide a fundamental insight to other TLCP containing thermoplastics where compatibilities may be present due to segmental interactions.     

K_2O－CaO－Al_2O_3－SiO_2系统自释釉瓷化学组成的研究

本文从酸度系数着手，证实了Ｋ２Ｏ－ＣａＯ－Ａｌ４Ｏ久－ＳｉＯ２系统中存在自释釉组成，限定了其组成范围，０．６７％＜Ｋ２Ｏ＜１．２８％，１０．６４％＜ＣａＯ＜１３．６２％，１１．５３％＜Ａｌ４Ｏ３＜１５．３２％，７２．７３％＜ＳｉＯ２＜７４．０４％，并讨论了自释釉瓷的性能。     

Electrocatalytic properties of NDGA and NDGA/FAD hybrid film modified electrodes for NADH/NAD redox reaction

The fabrication of monolayers composed of nordihydroguaiaretic acid (NDGA), and hybrid films composed of NDGA-flavin adenine dinucleotide (FAD) adsorbed films was performed in neutral aqueous solutions to produce electrochemically active thin films exhibiting one and two redox couples, respectively. An electrochemical quartz crystal microbalance and cyclic voltammetry were used to study the in situ growth of the NDGA and hybrid NDGA/FAD film monolayers. The NDGA modified film electrocatalytically oxidized NADH, ascorbic acid, dopamine, and N₂H₄ in neutral aqueous solutions. Well-separated voltammetric peaks were observed for dopamine and uric acid mixtures, and also for ascorbic acid and uric acid mixtures using the NDGA/GC modified electrode. When transferred to various aqueous buffered solutions, the two redox couples of the NDGA/FAD hybrid film and their formal potentials were observed to be pH-dependent. The electrocatalytic oxidation and reduction of NADH and NAD⁺ by a NDGA/FAD hybrid film in neutral aqueous solutions was carried out, and the electrocatalytic oxidation of NADH was performed using a NDGA/FAD hybrid film.     

农用聚乙烯调光膜的研制

本文介绍农用聚乙烯调光膜的制造、性能和应用。通过将稀土络合物调光剂和其他功能助剂添加到聚乙烯树脂中，经挤出塑化吹胀成型制得调光膜。膜的拉伸强度（纵／横）、断裂伸长率（纵／横）和直角撕裂强度（纵／横）分别为１７．２／１６．１ＭＰａ、４１３／４５７％、８１／８６ｋＮ；用红、兰、绿色调光剂可分别制得主峰波长为６１６ｎｍ的红光膜、４３６ｎｍ的兰光膜和５４０ｎｍ的绿光膜，其中以红光膜最佳。经农田实际应用表明     

Theoretical Aspects Of The Kinetics Of Competitive First Reactions Of Ozone In The O3/H2O2 And O3/UV Oxidation Processes

Kinetics of competition between the ozone direct reaction with compounds in water, ozone-hydroperoxide ion reaction leading to free radicals in the O₃/H₂O₂ process, and the photolysis of ozone in the O₃/UV process are discussed in terms of diffusion and reaction times to establish conditions for these reactions to be competitive. Film theory and chemical kinetic concepts then are applied to estimate initial rates of ozone absorption and consumption, removal rates of compounds present in water, and the importance of the radical oxidation path versus direct ozone and/or photolysis reactions.     

The permeation resistance of interface and the directional dependence of permeation in plasma-grafted composite membranes

Composite membranes were prepared by grafting plasma-polymerized films onto the surface of nonporous poly (dimethylsiloxane) films. Gas permeabilities of the composite membranes were measured at 35°C, 1 atm for N₂, 0₂, CO₂ and CH₄. The permeation properties of the composite membrane was analyzed using the series resistance model. There was a great interfacial resistance to CH₄ permeation through the composite membrane. The interfacial resistance was negligible for the other gases. The interfacial resistance seems to be a result of an interfacial layer caused by the interaction between the bulk two layers. For CH₄ gas, the permeation rate through the composite membrane was affected by the direction of flow. The directional dependence was negligible for the other gases.     

Evaporative Heat Transfer of Annular Two-phase Flow of Air-water in a Small Vertical Tube

The evaporative heat transfer of the non-boiling annular two-phase flow of air-water in a small vertical tube with uniform wall heat flux was studied both theoretically and experimentally. A simplified two-phase flow boundary layer model was used to calculate the thickness of the water film attached to the wall, and from the liquid film thickness the evaporative heat transfer coefficients of the annular two-phase flow were obtained. Theoretical equations and semi-theoretical equations were proposed for predicting the evaporative heat transfer of the annular two-phase flow of air-water in a small vertical tube. The semi-theoretical prediction agrees well with the experimental data. The mechanism of the heat transfer enhancement is the evaporation of the thin liquid film attached on the wall.