Papers by Keyword: Adhesion

Abstract: In the last decade, wide research was carried out on developing light-weight materials with improved mechanical properties, for instance comparable specific stiffness and strength, improved isolation, superior vibration and sound damping properties. To satisfy the increasing demands, Metal-Polymer-Metal Laminates have been numerously developed. Here, a short background of composites structures is presented.

Abstract: The authors of presented research case focused on possibilities of sealing porous as well as non – porous materials and analysed the measured results. It is the second article of the above mentioned authors dealing with sealed joints, however, in this case study the focus was placed on a group of industrially manufactured modified silyl polymer and polyurethane sealants. The research is based on the modified test procedure for the determination of adhesion and cohesion properties during maintained extension at variable temperatures, i.e. a high temperature of (70 + 2) °C and a temperature simulating freezing, i.e. (-20 + 2) °C, according to the European standard EN ISO 9047. The degree of specimen extension was set to amplitude of 20.0 % and the aim of the research case was to discover any differences that might appear in the resistance. The measured results demonstrate that there are significant differences between individual sealants in the results they provide in combination with specific material, e.g. wood appears to be a problematic substrate as well as glass cement or aluminium.

Abstract: Properties of geopolymer coating on nonmetallic substrates, especially glass fiber-reinforced epoxy (GRE) have been considered based on the effect of Si/Al ratio and surface treatment at a determined proportion of solid to liquid (S/L) and curing temperature.Kaolin and white clay have been used as geopolymer raw material in study of adhesive strength in geopolymer coating. Effect Si/Al ratio and surface treatment on adhesive strength has been tested from 0.40-0.60using Elcometer 106 Pull Off. The answer shows that Si/Al ratio and surface treatment were effecting the adhesive strength of geopolymer coating. The highest adhesive strength 6.0 MPa was found ina Si / Al ratio of 3.5 with surface treatment.

Abstract: This paper presents the results of a combined analytical, computational and experimental study of adhesion and degradation of Organic Light Emitting Devices (OLEDs). The adhesion between layers that are relevant to OLEDs is studied using force microscopy during Atomic Force Microscopy. The interfacial failure mechanisms associated with blister formation in OLEDs and the addition of TiO₂ nanoparticles (into active regions) are then elucidated using a combination of fracture mechanics/finite element modeling and experiments. The blisters observed in the models are shown to be consistent with the results from adhesion and interfacial fracture mechanics models. The implications of the work are discussed for the future design of OLED structures with improved lifetimes and robustness.

Abstract: This paper explored the effects of pressure on contacts between layers of organic photovoltaic cells with poly (3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) as the active layer. The contacts between the layers are modeled using analytical concepts and finite element models. The potential effects of surface roughness and dust particles are modeled along with the effects of lamination pressure and adhesion energy. The results show that, increased pressure is associated with decreased void length or increased contact length. The contacts associated with the interfaces between the active layer and the hole/electron injection layer poly (3,4-ethylenedioxythiophene: poly styrenesulphonate (PEDOT.PSS) and Molybdenum trioxide (MoO₃) are also compared. The implications of the results are discussed for the design of stamping/lamination processes for the fabrication of organic photovoltaic cells.

Abstract: We examine the fundamental operation of an Organic Light Emitting Device with emphasis laid on the Hole Transport Layer (HTL) and the optoelectronic properties of the other layers that make up the device. Investigation of the adhesion properties together with surface morphology, electrical and optical characterization of the different layers of the device was carried out. Poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT: PSS) was used as the conventional HTL material in the first case. This yields the reference device or system under studies. In the second case, PEDOT: PSS was replaced by an inorganic material, molybdenum trioxide (MoO ₃ ). The device performance in case two (2) revealed an improvement in performance. A couple of deposition techniques were examined together with the analysis of their effect on the resultant device properties. With the aid of theoretical models, we quantified the results obtained in terms of average pull-off forces and corresponding adhesion energies. The Derjaguin-Muller-Toporov model was utilized to model the adhesion energies between interfaces of adjacent layers of the device. Results that delineate modeling of charge transport across device interfaces are shown including the effects of pressure on the device optoelectronic properties.

Abstract: This paper presents the results of an experimental study of the effects of adhesion between gold nanoparticles and surfaces that are relevant to the potential applications in cancer detection and treatment. Adhesion is measured using a dip coating/atomic force microscopy (DC/AFM) technique. The adhesion forces are obtained for dip-coated gold nanoparticles that interact with peptide or antibody-based molecular recognition units (MRUs) that attach specifically to breast cancer cells. They include MRUs that attach specifically to receptors on breast cancer cells. Adhesion forces between anti-cancer drugs such as paclitaxel, and the constituents of MRU-conjugated Au nanoparticle clusters, are measured using force microscopy techniques. The implications of the results are then discussed for the design of robust gold nanoparticle clusters and for potential applications in localized drug delivery and hyperthermia.

Abstract: This paper presents the results of a study of the adhesion and optical properties of layered structures that are relevant to stretchable organic solar cells. A combination of modeling and experiments is used to investigate the effects of adhesion and stretching on failure mechanisms and optical properties. The adhesion between the possible bi-layers is determined by incorporating force microscopy measurements of pull-off forces into adhesion models. The failure mechanisms associated with the tensile stretching of the structures are then investigated using a combination of in-situ/ex-situ microscopy observations and analytical/computational models. The resulting changes in optical properties are elucidated before discussing their implications for the design of stretchable organic solar cells

Abstract: In materials industries, composite is an emerging material known for its low weight - high strength. The composite is a material that contains two different phases in order to create particular properties. The synthetic composites require a large quantum of energy and also the environment is being affected due to the pollution generated during the production and recycling. This draws the attention to use natural fibers as it is lower in cost and biodegradable. In this work, the chemical treatments of the banana and abaca natural fibers are carried out to modify the surface, stop the moisture absorption and improves the adhesion. The chemical treatment is carried out for both fibers separately in 10% concentrated sodium hydroxide for a duration of five hours and 5% concentrated potassium permanganate for a duration of two hours. The composite materials are fabricated using treated fiber and untreated fiber individually with general polymer resin by the hand lay-up process. The fabricated composites are tested to evaluate mechanical properties such as tensile, impact and flexural strength as per the ASTM standards. The mechanical properties of the treated fiber and untreated fiber are compared and it is found that the mechanical properties have been significantly improved due to the chemical treatment.

Abstract: In this study, the surface of a Piston Ring in the engine is coated with multilayered coating powder using plasma-spray technique, and its surface behavior is subsequently analyzed. The purpose of this study is to analyze the mechanical and thermal effects of surface coating for a Piston Ring during friction. Here specimens with and without coatings were prepared and then microstructure, hardness and corrosion tests were carried out. From the experimental results and Ansys results, it has been found that the coated specimen has improved the properties in improving the diesel engine performance. The results show less deformation and fewer scratches due to wear on the multilayer coated Piston Ring as compared to the uncoated one. The surfaces topography and the structure of the plasma spray coatings is observed on the scanning Electron microscope. The evaluation of the adhesion of coatings is made using the hardness test and also compared using the thermal barrier properties. Taking into account the results of measurements, one can state that the lowest wear and thermal resistance on piston rings by plasma spray coating.