Adhesion of a rigid punch to a confined elastic layer revisited

The adhesion of a punch to a linear elastic, confined layer is investigated. Numerical analysis is performed to determine the equivalent elastic modulus in terms of layer confinement. The size of the layer relative to the punch radius and its Poisson’s ratio are found to affect the layer stiffness. The results reveal that the equivalent modulus of a highly confined layer depends on its Poisson’s ratio, whereas, in contrast, an unconfined layer is only sensitive to the extent of the elastic film. The solutions of the equivalent modulus obtained from the simulations are fitted by an analytical function that, subsequently, is utilized to deduce the energy release rate for detachment of the punch via linear elastic fracture mechanics. The energy release rate strongly varies with layer confinement. Regimes for stable and unstable crack growth can be identified that, in turn, are correlated to interfacial stress distributions to distinguish between different detachment mechanisms.     

Adhesive contact and kinetics of adherence between a rigid sphere and an elastomeric solid

The adhesive contact of rigid spherical punches on viscoelastic solids is studied using a solution of the axisymmetric Boussinesq problem, assuming an integral constant to be non-zero. The JKR theory, based on the energy balance, is then found. The stress tensor is computed by superposition of the Hertzian stress tensor and the flat punch stress tensor, and is plotted for two particular cases: zero and minimum negative applied loads. It is shown that, whatever the load, the existence of molecular attraction forces provokes infinite stresses at the edge of the contact area.Fracture mechanics concepts are used to study the kinetics of adherence. It is shown that the general equation used allows the kinetics of interfacial crack propagation to be predicted in all types of test: fixed load; displacement; loading velocity; and crosshead velocity. Finally, the problem of the tackiness of elastomers and the dwell time effect on adherence are examined.The experimental results collected in this review have been obtained for the contact surface glass ball/polyurethane. All the theoretical predictions are verified with a reproducibility of better than 2%.     

Adhesion of two elastic conforming solids with a single interface gap

The adhesive contact between a half-space with a single surface micro-groove and a flat half-space is investigated. Surface interaction is described by the Maugis–Dugdale adhesion model. The contact problem is reduced to a singular integral equation for a height of the interface gap, which is solved analytically. For evaluating widths of the gap and the adhesion zone, a system of two transcendental equations is obtained, which is solved numerically. Three stable equilibrium states are found. The gap width-applied pressure curves are characterized by discontinuities and hysteresis. The effects of the maximum groove height and the adhesive stress on the adhesive contact are studied. It is shown that the adhesion hysteresis is greater for smaller grooves and larger adhesive stresses.     

Measurement of the adhesion between single melamine-formaldehyde resin microparticles and a flat fabric surface using AFM

An understanding of the adhesion of microparticles, particularly microcapsules, containing a functional component to a fabric surface is crucial to an effective application of this component to the fibre. Fabric surface is very rough; hence, direct measurement of the adhesion of single microparticles to surfaces with a roughness greater than the particle diameter is difficult. In the study reported here, cotton films were generated by dissolving cotton powder in an organic solvent and their properties including surface roughness, thickness, contact angle and purity were characterised. The adhesive forces between single melamine-formaldehyde (MF) resin microparticles and a cotton film under ambient conditions with a relative humidity of above 40% were measured using atomic force microscopy; they are considered to be dominated by capillary forces. It was found that there was little adhesion between a MF microparticle and a cotton film in an aqueous solution of sodium dodecylbenzene sulphonate as surfactant. Repulsion between them was observed, but it reduced with increase in the surfactant concentration and decrease in the pH of the solution. The repulsion contributions are thought to originate mainly from electrostatic repulsion. It is believed that the studies on the adhesion between single MF microparticles and a cotton film under ambient conditions or dispersed in surfactant solutions, are beneficial to the attempts to enhance the adhesion of microcapsules to fabric surfaces via a modification of their surface composition and morphology.     

钴盐对钢丝帘线与橡胶粘合性能的影响

对环烷酸钴，硼酰化钴，新癸酸钴等钴盐粘合增进剂对高和低铜质量分数钢丝帘线与橡胶粘合性能的影响进行了研究。结果表明，胶料中加入钴盐能够提高强伸性能和与钢丝帘线的初始粘合唱 力及耐盐水老化能力。     

An analytical approach for the adhesion of a semi-infinite elastic body in contact with a sinusoidal rigid surface under zero external pressure

An analytical approach for the adhesion of a semi-infinite elastic body in contact with a sinusoidal rigid surface under zero external pressure is presented. Although Johnson (Int. J. Solids Struct. 32, 423 (1995)) has proposed an analytical solution for a slightly wavy surface, while Zilberman and Persson (Solid State Commun. 123, 173 (2002); J. Chem. Phys. 118, 6473 (2003)) have given a numerical solution for a highly wavy surface by considering the curvature of the contact area in the calculation of the interfacial term of the total energy, our solution is not only for small amplitude of roughness (i.e., the slightly wavy surface as Johnson's) but also for large amplitude of roughness (i.e., the highly wavy surface as of Zilberman and Persson). Our solution considers the curvature of the contact area as do Zilberman and Persson. Our results which are obtained for the total energy and equilibrium condition of the system agree with both Johnson's and Zilberman and Persson's results. The effects of the material constants and the surface roughness on the adhesion are clearly expressed and discussed.     

Adhesion studies of radio-frequency sputtered SiO2 films on Ti,stainless steel,Ni and Inconel substrates. Effects of substrate surface ion bombardment etching

The scratch test was applied to determine the adhesion strength of radio-frequency (RF) sputtered SiO₂ films to Ti, stainless steel, Ni and Inconel substrates. The effect of substrate ion bombardment etching was investigated by using a mean critical load derived from a Weibull-like statistical analysis. It was found that the mean critical load values obtained on substrates etched by ion bombardment for a sufficiently long time were two to three times those obtained on mechanically polished substrates. Scratch tracks were observed by scanning electron microscopy and some X-ray spectra were measured after the electron beam of the scanning electron microscope was focused inside the scratch channel. Depth composition profiles were also recorded by Auger electron spectroscopy. No important presence of contamination was observed in the interfacial domain even after mechanical polishing, but the width of this interfacial domain was higher after ion bombardment than after mechanical polishing. This difference in width could result from the formation of microcavities and vacancies at the substrate surface during ion bombardment. In such a case, the significant adhesion improvement should principally occur from an enhanced interlocking of the coating to its substrate.     

Adhesion of air bubbles to a fluorite surface in the presence of oleate species

Measurements of the detachment force of air bubbles from a surface of fluorite covered with an oleate film immersed in an aqueous sodium oleate solution or water were carried out. The contact angles for the systems fluorite/oleate film-drop of aqueous sodium oleate solution-air, fluorite/oleate film-air bubble-aqueous sodium oleate solution, and fluorite/oleate film-air bubble-water were also measured. The detachment forces were also calculated from the measured contact angles. It was found that the adhesion of air bubbles to the fluorite surface increased considerably in the presence of an oleate film on the fluorite surface, but decreased if the oleate film was at the water-air interface. Good agreement between the theoretically calculated and the measured values of the detachment force for the system fluorite/oleate film-air bubble-sodium oleate aqueous solution when the concentration of this latter solution was in the range 0 to 87.1 mg/dm³ was also found, but for concentrations over 87.1 mg/dm³ the calculated values of the detachment force were higher than the measured values. The calculations and measurements indicate that the most favourable condition for the adhesion of air bubbles to fluorite grains is the presence of a chemisorbed film of oleate without surface precipitation of calcium oleate salt at low concentrations of oleate species in water.     

Adhesion between an underfill and the passivation layer in flip-chip packaging

An underfill is used to fill the gap between the integrated circuit chip and substrate to improve the solder joint fatigue life in flip-chip packaging. The influence of aging in an environment with a high temperature and a high humidity on the adhesion performance of an underfill material (epoxy cured with acid anhydride) to the passivation layer in flip-chip packaging is discussed. Adhesion of the underfill to all passivation materials investigated degrades after aging in a high temperature and high humidity environment. The extent of this degradation is dependent on the hydrophilicity of the passivation layer surface. Hydrophilic passivation layer surfaces, such as silicon dioxide (SiO₂) and silicon nitride (Si₃N₄), show much more severe adhesion degradation than hydrophobic passivation layer surfaces, such as benzocyclobutene (BCB) and polyimide (PI). The mobility of both the absorbed water and polymer chains is studied with solid state nuclear magnetic resonance (NMR) spectroscopy. Higher mobility of both the absorbed water and polymer chains in the rubbery state of polymers contributes to faster adhesion degradation during high temperature and high humidity aging. The adhesion stability of hydrophilic passivation layers can be successfully improved by use of a silane coupling agent that introduces a stable chemical bond at the interface. A flow micro-calorimeter is used to study the adsorption of silane coupling agents onto glass surface. The difference in adhesion retention improvement between aminosilane and epoxysilane is discussed.     

Exploring the effect of electron beam on swelling,gel fraction,mechanical and thermal properties of ethylene acrylic elastomer/millable polyurethane rubber blends

ABSTRACT

Ethylene acrylic elastomers (AEM) and millable polyurethane (MPU) blend have been prepared successfully using dicumyl peroxide (DCP) system and the blend ratio is optimised on the basis of the tensile results. The optimised unvulcanised blend ratio (60:40) is subjected to different electron beam (EB) dose to obtain uniform three dimensional crosslinking networks. The characteristic shifting of?=?CO vibration in the Fourier-Transform Infrared spectra confirms the formation of hydrogen bonding between the two phases. The phase morphology of the two phases in the optimised blend has been captured in SEM and the results show the successful integration of MPU in AEM phase. It is found that the swelling of the irradiated blend decreases with increase in EB dose, whereas the increase in gel fraction and the crosslink density is due to the irradiation-induced crosslinking. The thermal stability of the irradiated blend has been improved in compression to the pristine form of individual phase.     

Effect of the Molecular Length of n-Alkylsilanes on the Adhesion at a Rubber/Glass Interface

The effect on the peeling energy, G, of glass/styrene-butadiene rubber (SBR) assemblies of the length, N, of the alkyl chain, ranging from 4 to 30 carbon atoms, of silane coupling agents is determined. Experimentally, it is shown that G strongly increases with N. Therefore, considering that the rheological model of adhesion (or model of multiplying factors) is valid, G is assumed equal to the product of three terms: the reversible adhesion energy, W. at the interface, the viscoelastic dissipation factor, φ, of SBR and a “molecular factor” to be determined. Finally, it appears that this latter factor depends linearly on N. Such a result should be consistent with an extraction (“suction”) process of the silane alkyl links from bulk SBR during peeling experiments.     

Effect of the Molecular Length of n-Alkylsilanes on the Adhesion at a Rubber/Glass Interface

The effect on the peeling energy, G, of glass/styrene-butadiene rubber (SBR) assemblies of the length, N, of the alkyl chain, ranging from 4 to 30 carbon atoms, of silane coupling agents is determined. Experimentally, it is shown that G strongly increases with N. Therefore, considering that the rheological model of adhesion (or model of multiplying factors) is valid, G is assumed equal to the product of three terms: the reversible adhesion energy, W. at the interface, the viscoelastic dissipation factor, φ, of SBR and a “molecular factor” to be determined. Finally, it appears that this latter factor depends linearly on N. Such a result should be consistent with an extraction (“suction”) process of the silane alkyl links from bulk SBR during peeling experiments.     

Comparison between the adherence of a rigid axisymmetrical cone and a truncated one,in adhesive contact on an elastic half-space

We compare the equilibrium contacts and the kinetics of adherence of an axisymmetrical rigid cone and a flat-ended one with the same angle, applied against the flat and smooth surface of a soft elastomer sample (unfilled vulcanized natural rubber, cured with dicumyl peroxide), with the help of fracture mechanics concepts which can easily be introduced in this class of problems by using Sneddon's solution (1965) of Boussinesq's problem extended to all axisymmetric adhesive punches with a convex profile. The kinetics of adherence are measured when an imposed tensile force is applied in order to disturb the size of the contact area. Variations of the strain energy release rate, G, and of the associated dissipation function | =(G m w)/w, where w is the Dupré energy of adhesion, are studied as a function of the parameter, a T ± V, in which V is the crack propagation speed at the interface between a cone and a truncated one made of glossy Plexiglass®, and the rubber sample (the limit of the contact is considered as a crack tip), and a T , is the shift factor of the Williams-Landel-Ferry transformation. As expected, a master curve | (V) is found, confirming the variation of | as the power function V 0.55 , at fixed temperature, as recently established by Barquins et al. in adherence of a flat ended sphere and cone in pull-off/push-on tests, adherence and rolling of cylinders experiments and rebound of balls tests, with the same elastomer. Present results lead to propose one to write | =k ± (a T ± V) 0.55 , k=2520 and V being valued using S.I. units, for the reference temperature θ=25°C, with a quite good accuracy in the order of 1%.     

Revisit the adhesive contact between a nanoscale rigid sphere and an elastic half-space: considering the effect of sphere size

The current paper revisits the adhesive contact between a rigid nanoscale sphere and an elastic half-space. Using analytical solution for traction and a modified numerical scheme, a new simulation is proposed. The adhesive contact is simulated faster and more easily than previous researches. The effect of sphere size is investigated. A modified spherical JKR model and spherical DMT model are proposed. The results are compared with spherical JKR, spherical DMT, and rigid sphere model. The load–approach and contact radius–load relations can be predicted by the modified spherical JKR model for sphere radius larger than 50?. Finally, approximation equations for pull-off force vs. Tabor parameter and jump-in distance vs. Tabor parameter are proposed.     

钴盐用量对橡胶与钢丝帘线粘合性能的影响

对硼酰化钴ＭＣ２３（钴质量分数为２３％）用量（０６～１６份）对橡胶与钢丝帘线粘合性能的影响进行研究。采用的基本配方为：ＮＲ１０００；炭黑Ｎ３２６６２０；芳烃油８０；氧化锌９０；硬脂酸０５；防老剂４０２０２０；不溶性硫黄ＩＳ７０２０６０；促进剂ＤＺ１０；粘合剂ＲＳ３５；粘合剂Ａ２３；沉淀法白炭黑５０。结果表明，随着钴盐用量的增大，在未老化、热空气老化及盐水老化条件下，胶料与钢丝的粘合强度有所提高；在湿热老化条件下，粘合强度由于热量和湿气的交互作用而发生较大幅度的下降，但钴盐用量在１０份时粘合强度的下降为最小。综合胶料初始和老化后的应力应变性能和粘合强度，以１０份钴盐用量为最佳。     

Local Bending Moment as a Measure of Adhesion: The Blister Test

We propose to characterize joints between materials by the maximum bending moment, M_max, borne just prior to delamination. We suggest to evaluate M_max in the blister test geometry through direct measurement of the blister curvature in the vicinity of the separation line and employ a scanning capacitance microscope for the blister profiling. The methodology and apparatus were tested on measurements of adhesion of two commercial polymer films to Plexiglas and Teflon.     

Effect of Anion in Cobalt Promoters on the Adhesion between Steel Cord and Rubber Compound

There is widespread use of two main groups of adhesion promoters, the SRH-system and an organic cobalt salt. They are used either jointly or individually in the rubber compound for promotion and maintenance of good adhesion of rubber to brass-coated steel cord in radial tyres.

This paper describes the influence of anions associated with cobalt promoters on the adhesion energy and the pull-out force between brass-coated steel cord and rubber and their relationship to other relevant physical properties, under the influence of various environments which simulate tyre service conditions.

It is observed that incorporation of a cobalt promoter greatly enhances the adhesion energy and influences the Young's modulus and crosslink density of the rubber compound in a similar fashion. The study establishes the supremacy of boroacylate among the anions considering its overall good performance and the protection offered against various hostile environments. However, the benefits of the cobalt promoter is not realised with stearate ion. The results are explained on the basis of chemical stability of the promoter and the properties of the interfacial film and the compounds.     

Modelling of particle resuspension by a turbulent airflow and the role of particle size,surface roughness and electric charge

A resuspension model based on the Lennard–Jones intermolecular potential is applied to a monolayer deposit of spherical particles. The model considers the interactions between a particle and a surface under the influence of an external turbulent airflow. The particle–surface interaction was modelled with and without particle deformation due to elastic flattening. The resuspension rate was calculated by a kinetic force-balance approach whereby particle detachment occurs when the instantaneous joint contribution of the lift and drag forces exceeds the total adhesive force of the particle–surface system. Enhanced aerodynamic particle removal driven by the moment of the lift and drag forces was determined. Model predictions suggest that inclusion of the moment of the aerodynamic forces provides a suitable model for particle detachment (initiated by rolling). The importance of elastic deformation was found to depend on adhesive forces, characteristics of the substrate surface (surface roughness) and particle size. The model was applied to a number of laboratory experiments. For one set of experiments, we identified two resuspension regimes depending on whether small non-deformable or large deformable (equivalently, strongly or weakly bound) particles resuspended at high or low friction velocities. A modified model incorporating the effect of particle charge is also presented. Results indicate that particle resuspension is possible even when electrostatic forces are present, but the resuspension rate decreases considerably, depending on particle size, particle charge and surface roughness.     

Adhesion of polyimides to metal and ceramic surfaces: an overview

Experimental and theoretical results on polyimide-to-metal and -ceramic adhesion are briefly reviewed. In general, the polyimide-on-metal interfaces have stronger interactions vis-a-vis the metal-on-polyimide interfaces. A section is also devoted to adhesion promoters and their effect on the adhesion. Data from the literature imply that one of the reasons for the improvement in adhesion in the case of the polyimide-on-silicon oxide interface using a y-aminopropyltriethoxysilane adhesion promoter is physical in nature. With the adhesion promoter the interfacial region within the polyimide is likely to be less oriented and more entangled than the same system without the adhesion promoter. This subtle effect is illustrative of the understanding that can result from careful locus-of-failure analysis in an adhesion study.     

硼酰化钴对橡胶与镀黄铜钢丝粘合性能的促进作用

研究了硼酰化钴对橡胶与镀黄铜钢丝粘合性能的促进作用。试验结果表明,加入硼酰化钴ＲＣＢ１６和ＲＣＢ２３ 能大大提高橡胶与镀黄铜钢丝的粘合性能,在耐盐水老化和湿热老化等方面的效果尤为显著,并分别与Ｍａｎｏｂｏｎｄ Ｃ１６ 和Ｍａｎｏｂｏｎｄ ６８０Ｃ 水平相当。