Viscoelastic properties and lap shear strength of EVA/aromatic hydrocarbon resins as hot-melt adhesives

A series of ethylene vinyl acetate (EVA) copolymers were blended with aromatic hydrocarbon resins in the molten state in various ratios and possible relations between viscoelastic and adhesion properties as hot-melt adhesives (HMAs) were investigated. When the softening point of aromatic hydrocarbon resin was high and the concentration of aromatic hydrocarbon resin was low, the tan δ peak height decreased and broadened. This result corresponds to the miscibility of the blend. The single lap shear strength increased with increasing softening point of the aromatic hydrocarbon resin and it reached a maximum value with increasing temperature. A large scatter was observed in lap shear strength values, which were higher at higher test rates and lower temperatures, and under these conditions interfacial failure occurred.     

Interfacial shear strength of wood–plastic composites: a new pullout method using wooden dowels

This preliminary study examined the relationship of interfacial shear strength (IFSS) to modulus of rupture (MOR) for several different wood–plastic composites (WPCs). Plastics utilized were high-density polyethylene (HDPE) and polypropylene (PP). Pine and oak were used as the wood species. Compatibilizers used included maleic-anhydride-grafted polyethylene (MAPE) and maleic-anhydride-grafted polypropylene (MAPP). A strong correlation between IFSS and MOR was observed in a limited composition region. PP/oak WPCs showed poor correlation between MOR and IFSS, probably due to the roughness of the oak surface. Compatibilizer systems incorporating liquid components did not give good results and appeared to be inappropriate for this test method.     

The effects of nanostructure and composition on the hydrophobic properties of solid surfaces

The effects of nanoroughness and chemical composition on the contact and sliding angles on hydrophobic surfaces were studied theoretically and experimentally. A theoretical model based on forces developed at the contact area between a liquid drop and hydrophobic smooth or nanoroughened surface was developed and compared with the existing models, which are based on forces developed at the periphery between the drop and the solid surface. The contact area based model gives rise to an interfacial adhesion strength parameter that better describes the drop-sliding phenomenon. Consequently, relationships were derived describing the dependence between the interfacial adhesion strength of the liquid drop to the surface of a given composition, the mass of the drop, the measured contact angles and the sliding angle. For a given surface chemistry, the sliding angle on a nanometric roughened surface can be predicted based on measurements of contact angles and the sliding angle on the respective smooth surface. Various hydrophobic coatings having different surface nanoroughnesses were prepared and, subsequently, contact angles and sliding angles on them as a function of drop volume were measured. The validity of the proposed model was investigated and compared with the existing models and the proposed model demonstrated good agreement with experimental results.     

Superconducting Bi(2223) thick film on Ba2HoNbO6: a new perovskite ceramic substrate

Abstract

Barium holmium niobate Ba₂HoNbO₆ (BHNO) has been developed as a new substrate for (Bi,Pb)₂Sr₂Ca₂Cu₃O_x (Bi(2223)) superconductor film. Ba₂HoNbO₆ has a cubic perovskite structure with lattice constant a = 8·26 Å. The dielectric constant and loss factor of this material are in a range suitable for its use as a substrate for microwave applications. The Bi(2223) superconductor shows no detectable chemical reaction with BHNO, even under extreme processing conditions. Dip coated Bi(2223) thick film on Ba₂HoNbO₆ substrate had T _c(0) of 109 K and current density of around 4 × 10³ A cm ^{- 2} at 77 K and in zero magnetic field.     

Determination of dynamic contact angles in solid–liquid–liquid systems using the Wilhelmy plate apparatus

The purpose of this work was to carry out a systematic study of the effects of brine composition and rock mineralogy on rock-oil-brine interactions taking place in petroleum reservoirs. These terms are generally lumped into a single term called wettability in petroleum engineering. The extent of wetting of the rock surface by water or oil depends on the dynamic contact angles measured in such a mode as to enable movements of the three-phase contact line. The Wilhelmy plate technique has been used in this study to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle) at the solid-liquid interface. The water-advancing and water-receding contact angles have been calculated from the adhesion tensions by making independent measurements of the liquid-liquid interfacial tensions using a du Noüy ring tensiometer. The water-advancing and receding angles have been measured in this study for pure hydrocarbons against synthetic brines of different concentrations. Polished surfaces of glass slides and dolomite have been used to simulate the reservoir rock surfaces. A nonionic surfactant (ethoxy alcohol), which is being used in Yates reservoir in West Texas for enhancing oil recovery, was used to quantify its wettability effects. The results of the systematic experimental investigation of the effects of practical variables on wettability are presented. It is found that interactions between surface-active agents at the interface of two liquids have an effect on wettability alteration. The composition and concentrations of different organic and inorganic chemical species have a major effect in making a reservoir oil-wet or water-wet.     

Cyclic loading effect on tribological tests during intermetallic contacts of long chained hydrocarbons

Abstract

High value of coefficient of friction was obtained for dry friction between AISI 304 stainless steel specimen and counter body made from 100Cr6 steel. Aliphatic hydrocarbon liquid films of dodecane (C₁₂ H₂₆ ) and monounsaturated oleic acid (C₁₈ H₃₄ O₂ ) were used as lubricating layers between the above two contacting pairs. This was carried out to evaluate the effect of alkane and alkene liquid lubricants on the evolution of coefficient of friction. Furthermore, the cyclic loading effect of progressive and regressive loading on coefficient of friction was also evaluated. Sliding speed of the contacting bodies also varied. The loading and sliding effects resulted in interruption of hydrodynamic lubrication, which caused breaks in the superlubricity of these hydrocarbons. Such circumstances led to manifestation of higher coefficient of friction. Frictional behaviour of these contacting bodies during cyclic loading procedure has been correlated with deformation induced morphologies of wear tracks.     

孤东新滩油田KD18块普通稠油油藏降黏驱可行性研究

本文主要研究孤东新滩油田KD18块普通稠油油藏降黏剂驱的可行性,通过对降黏剂的界面性能、降黏性能及抗吸附性能评价的研究,设计适用于孤东新滩油田KD18块的普通稠油降黏剂。结果发现A-01、C-03、D-04、F-03这4种降黏剂适用于孤东新滩油田现场应用。     

Measuring effective interfacial shear strength in carbon fiber bundle polymeric composites

Adhesion in composite materials is often quantified using the single fiber fragmentation (SFF) test. While this method is believed to provide accurate values for the fiber–matrix interfacial shear strength (IFSS), these may not accurately reflect the macroscopic mechanical properties of specimens consisting of tows of thousands of tightly spaced fibers embedded in a resin matrix. In these types of specimens, adhesion may be mitigated by fiber twisting and misalignment, differences in the resin structure in the confined spaces between the fibers and, most importantly, by any incompleteness of the fiber wetting by the resin. The present work implements fiber band fragmentation (FBF) testing to obtain effective interfacial shear strengths, whose values reflect the importance of these factors. The fiber fragmentation in these specimens is tracked through the counting and sorting of acoustic emission (AE) events occurring during the tensile testing of the specimen and yields the average critical fiber fragment length. AE results, in conjunction with stress-strain data, show that fiber breakage events occur at acoustic wavelet amplitudes substantially greater than those generated by fiber/matrix debonding. Kelly–Tyson analysis is applied, using the measured critical fiber fragment length together with known values for the fiber diameter and tensile strength to yield the effective IFSS. FBF tests are performed on carbon fiber/poly(vinyl butyral) (PVB) dog-bone fiber-bundle systems, and effective IFSS values substantially lower than those typically reported for the single fiber fragmentation testing of similar systems are obtained, suggesting the importance of multi-fiber effects and incomplete fiber wetting.     

Analysis of the influence of atmospheric plasma spray (APS) parameters on adhesion properties of alumina-titania coatings

Alumina-13 wt% titania wear resistant coatings were deposited using the Atmospheric Plasma Spray (APS) process under several processing conditions. Coating adhesion was then measured locally on cross sections by the indentation test and results were correlated with process variables. In order to identify the most influential factors on adhesion, artificial intelligence was used. The analysis was based on an Artificial Neural Network (ANN) taking into account training and test procedures to predict the dependences of measured property on experimental conditions. This study pointed out primarily that adhesion was largely sensitive to parameters that modified the in-flight particle characteristics (i.e. velocity and temperature). These effects were quantitatively demonstrated and predicted with an optimized neural network structure.     

Interfacial Stresses in Plated Beams with Exponentially-Varying Properties

This paper presents a method for determining the elastic shear and peel stresses in an adhesive joint between a strengthening plate and a functionally graded beam (FGB). The beam is assumed to be isotropic with a constant Poisson's ratio and exponentially-varying elastic modulus through the beam thickness. Stress distributions, depending on an inhomogeneity constant, were calculated and presented in the form of graphs. It is shown that the inhomogeneities play an important role in the distribution of interfacial stresses. This research is helpful in understanding the mechanical behaviour of the interface and design of hybrid structures. The results presented in the paper can serve as a benchmark for future analyses of functionally graded beams strengthened by fibre reinforced polymer plates.