水敏性硅烷改性聚氨酯粘合剂

本文研究了水敏性硅烷改性聚氨酯粘合剂的配方及合成工艺条件并考查了其对玻璃－玻璃、玻璃－铁、铁－铁的粘接性能。     

Thermomechanical Vibration Behavior of FG Nanobeams Subjected to Linear and Non-Linear Temperature Distributions

In this study, thermomechanical vibration analysis of functionally graded (FG) nanobeams subjected to in-plane thermal loads are carried out by presenting a Navier-type solution and employing a semi-analytical differential transform method (DTM) for the first time. Two types of thermal loading, namely, linear and non-linear temperature rises through the thickness direction are considered. Thermomechanical properties of FG nanobeam are supposed to vary smoothly and continuously throughout the thickness based on power-law model and material properties are assumed to be temperature-dependent. Eringen non-local elasticity theory is exploited to describe the size dependency of FG nanobeam. Using Hamilton's principle, the non-local equations of motion together with corresponding boundary conditions are obtained for the free vibration analysis of FG nanobeams including size effect and they are solved applying DTM. According to numerical results, it was revealed that the proposed modeling and semi-analytical approach can provide accurate frequency results of the FG nanobeams as compared to analytical results and also some cases in the literature. A parametric study is included to examine the effects of several parameters, such as temperature rise, gradient index, small-scale parameter and boundary conditions on the normalized natural frequencies of the temperature-dependent FG nanobeams in detail. It is explicitly shown that the vibration behaviour of a FG nanobeams is significantly influenced by these effects. The new results can be used as benchmark solutions for analyses of FG nanobeams.     

Mechanical Property Enhancement of Ti-6Al-4V by Multilayer Thin Solid Film Ti/TiO2 Nanotubular Array Coating for Biomedical Application

With the intention of improving the mechanical properties of Ti-6Al-4V, samples were first coated with pure titanium using the physical vapor deposition (PVD) magnetron sputtering technique. The Taguchi optimization method was used to attain a higher coating on substrate adhesion. Second, pure titanium-coated samples with higher adhesion were anodized to generate TiO₂ nanotubes. Next, the TiO₂-coated specimens were heat treated at annealing temperatures of 753.15 K and 923.15 K (480 °C and 650 °C). The XRD results indicate that the varying heat treatment temperatures produced different phases, namely, anatase [753.15 K (480 °C)] and rutile [923.15 K (650 °C)]. Finally, the coated samples’ mechanical properties (surface hardness, adhesion, and fretting fatigue life) were investigated. The fretting fatigue lives of TiO₂-coated specimens at 753.15 K and 923.15 K (480 °C and 650 °C) annealing temperatures were significantly enhanced compared to uncoated samples at low and high cyclic fatigue. The results also indicate that TiO₂-coated samples heat treated at an annealing temperature of 753.15 K (480 °C) (anatase phase) are more suitable for increasing fretting fatigue life at high cyclic fatigue (HCF), while at low cyclic fatigue, the annealing temperature of 923.15 K (650 °C) seemed to be more appropriate. The fretting fatigue life enhancement of thin-film TiO₂ nanotubular array-coated Ti-6Al-4V is due to the ceramic nature of TiO₂ which produces a hard surface as well as a lower coefficient of friction of the TiO₂ nanotube surface that decreases the fretting between contacting components, namely, the sample and friction pad surfaces.     

低温等离子体技术在高分子材料中的应用研究进展

简要介绍了低温等离子体的定义。综述了近年来低温等离子体技术在高分子材料中应用的最新进展,重点介绍了等离子体技术在纤维织物、塑料、多孔材料、生物材料等改性中的研究进展。阐述了等离子体在材料处理中的应用效果如亲水性、拒水性、黏合性、可纺性、染色整理性能、阻燃性、抗静电性等。最后,指出低温等离子体技术目前存在的问题。     

Experimental investigation of the effect of dispersed silica and alumina nanoparticles on oil-aqueous phase interfacial tension

This work experimentally investigated silicon oxide and aluminum (III) oxide nanoparticles as enhanced oil recovery agents and their effects on wettability and interfacial tension of oil-wetted sandstone and carbonate rocks. The two nanoparticles were selected based on a screening of commercially available nanoparticles with considering the most important parameters. The required time and treatments for the rock samples to become oil-wet, and the required time for the nanofluid to treat each rock sample were also experimentally investigated. Results of this study show that the nanoparticles alter wettability of sandstone and carbonate rocks from oil-wet to water-wet state. It is also observed that sandstone samples are more effected than limestone ones and alumina nanoparticles have greater potential to alter the rock wettability.     

Experimental investigation of effect of asphaltene deposition on oil relative permeability,rock wettability alteration,and recovery in WAG process

Asphaltene deposition is considered to be one of the most problems during oil productions. This work describes the effect of asphaltene precipitation and deposition on relative permeability of reservoir rock during water alternating gas (WAG) injection process. The main objective of this work is experimental investigating of relative permeability change of reservoir fluid due to asphaltene deposition on application of WAG process by use of core flood setup. Result of this paper investigate the relative permeability change during WAG process with different asphaltene content that help to make better development decisions for a reservoir with fluid with specific asphaltene content.     

橡胶型氯化聚乙烯的并用

研究了不同橡胶型氯化聚乙烯(CM)并用时硫化体系及条件、增强体系和增塑剂对并用胶硫化行为及性能的影响.结果表明,将不同的CM并用改善了硫脲-硫黄硫化体系的硫化行为,出现了硫化平坦区.硫化温度为160℃、硫化时间为50 min时,CM并用硫化胶的拉伸强度达到14.8 MPa;将质量比为50/50的炭黑N 375与N 774用于增强CM并用胶时,其硫化胶的永久变形最小;增塑剂有助于改善CM并用硫化胶的弹性及硬度,但其用量不宜过多,以30份(质量)为好;CM并用胶的各项性能指标均可以满足制备大型橡胶制品的要求.     

Wound dressings: Current advances and future directions

Wound healing is a complicated and continuous process affected by several factors, which needs an appropriate surrounding to achieve accelerated healing. Wound healing process recruits three different phases: inflammation, proliferation, and maturation. Due to the different types of wounds, as well as the advancement in medical technology, various products have been developed to repair different skin lesions. Our objective is to investigate the advancement in wound dressings from traditional to the current methods of treatment. The article presents the characteristics of an ideal wound dressing, the requirements for the appropriate selection of different types of wounds, and a detailed classification of wound dressings. Animal origin, herbal origin, and synthetic dressings are firstly introduced and reviewed. Then, nonmedicated dressings including alginate, hydrogel, and hydrocolloid dressings, as well as medicated dressings are discussed. Finally, the developmental prospectives of the new generations of wound dressings for future researches are presented. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47738.     

Electrochemical investigation of sulfonated poly(ether ether ketone)/clay nanocomposite membranes for moderate temperature fuel cell applications

In the present study, polyelectrolyte membranes based on partially sulfonated poly(ether ether ketone) (sPEEK) with various degrees of sulfonation are prepared. The optimum degree of sulfonation is determined according to the transport properties and hydrolytic stability of the membranes. Subsequently, various amounts of the organically modified montmorillonite (MMT) are introduced into the sPEEK matrices via the solution intercalation technique. The proton conductivity and methanol permeability measurements of the fabricated composite membranes reveal a high proton to methanol selectivity, even at elevated temperatures. Membrane based on sPEEK and 1 wt% of MMT, as the optimum nanoclay composition, exhibits a high selectivity and power density at the concentrated methanol feed. Moreover, it is found that the optimum nanocomposite membrane not only provides higher performance compared to the neat sPEEK and Nafion^®117 membranes, but also exhibits a high open circuit voltage (OCV) at the elevated methanol concentration. Owing to the high proton conductivity, reduced methanol permeability, high power density, convenient processability and low cost, sPEEK/MMT nanocomposite membranes could be considered as the alternative membranes for moderate temperature direct methanol fuel cell applications.