Physico-Chemical Criteria for Maximum Adhesion. Part I: Theoretical Concepts and Experimental Evidence

This paper presents an analysis of the literature with the aim of defining basic criteria and developing a general model to describe joint strength. Two particular cases of the relationship: cosθ = f(γ_L) have been identified as prerequisites for further analysis of interfacial phenomena and conditions governing their existence were discussed.

The fact has been pointed out, based on available experimental results, that for the most important case in practice where 0.6 ≤ cosθ ≤ 1.0, the relation cos θ = f(γ_L) can be treated as rectilinear. This finding will be utilized in the comprehensive development of criteria defining joint performance in Part II.

Variability of the interaction factor Φ for various systems has been investigated in relation to cos θ, for the identified particular cases of the relationship cos θ = f(γ_L) A special value of the interaction factor, ₀, was found. The importance of the rectilinear particular case of cos θ = f(γ_L) was shown, which involves constant factor Φ₀ instead of variable Φ.     

Physico-Chemical Criteria for Maximum Adhesion. Part II: A New Comprehensive Thermodynamic Analysis

In this paper, two parameters defined as the relative work of adhesion [W_A/γ_L] and the relative interfacial energy [γ_SL/γ_L] have been examined for their assumed usefulness in correlating the thermodynamic properties of the components of the system substrate/ adhesive with its practical performance (strength). It is shown that the minimum value of [γ_SL/γ_L] relevant to conditions for the maximum adhesion becomes zero only for those systems (relatively rare) for which interaction factor Φ₀ is equal to 1.0.

Several transition points were identified for boundary conditions acquired at θ = 0° and θ = 90° which can be used to predict the properties and performance of an adhesive joint. These transition points are: a_MIN—energy modulus of the system (E. M. S.), relevant to the minimum interfacial energy; a_S—E. M. S. where self-spreading of adhesive occurs; a_CRIT—E. M. S. relevant to conditions under which the thermodynamic work of adhesion becomes negative and the system exhibits a tendency for self-delaminating or has “zero-strength”; a_CF—E. M. S. beyond which the geometry of the interface at any interfacial void or boundary of the joint may be regarded as a crack tip.

It is shown that only in those systems for which Φ₀ = 1.0 can a minimum contact angle of 0° indicate a condition for the maximum strength. If Φ₀ is known, the optimum contact angle can be estimated and hence the optimum surface energy of the substrate (adjusted by surface treatment, etc.) for the maximum adhesion.     

基于模糊多准则决策理论优化化工设备的选材

基于模糊多准则决策理论，建立了化工设备待选材料主要评价因素的模糊决策矩阵，采用模糊折衷型评价方法进行材料优劣排序，实现了选材的优化。     

The Adhesion Society Award for Excellence in Adhesion Science-1994

The Adhesion Society Award for Excellence in Adhesion Science for 1994, sponsored by the 3M Company, will be presented to Professor Lawrence T. Drzal at the annual meeting of the Society at Orlando, Florida, February 21-23, 1994. Professor Drzal is Professor of Chemical Engineering and Materials Science and Mechanics, and the Director of the Composite Materials and Structures Center, Michigan State University, East Lansing, Michigan. Professor Drzal is cited in the award:     

Optimum Polymer - Solid Interface Design for Adhesion Strength: Carboxylation of Polybutadiene and Mixed Silanes Surface Modification of Aluminum Oxide

To understand the optimum design of polymer-solid interfaces for adhesion strength, model polymer-solid interfaces of carboxylated polybutadiene(cPBD) adhered to mixed silane modified Al₂O₃ surfaces were examined. The cPBD, having various ?COOH sticker group concentration φ(X) (0 ～ 10 mol%), was synthesized through high-pressure carboxylation of PBD, while Al₂O₃ surfaces were modified to have various -NH₂ density, φ(Y) (0 ～ 100 mol%), using self-assembly of mixed amine- and methyl-terminated silanes. The coadsorption kinetic model of the two silanes was analyzed through X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), and dynamic contact angle (DCA), which gave the capability of controlling the receptor concentration of aluminum oxide surfaces. The polymer surface chain responses after exposure to various media were understood by measuring contact angle changes of various probe liquids. T-peel tests of the model polymer–solid interfaces, as a function of time and sticker and receptor group concentrations showed much longer time dependence than the characteristic time of a bulk polymer chain. Additionally, the classical equation of interface failure was re-examined to see the effects of deformation rate, annealing temperature, and annealing time. A simple scaling analysis of free energy of an adsorbed polymer on a solid surface was extended to predict the adhesion potential of the model polymer–solid interfaces. From the experiments and theory of adhesive vs. cohesive failure, it was found that there existed an optimum product value r* = φ(X)φ(Y)χ of sticker concentration φ(X), receptor concentration φ(Y), and their interaction strength χ, which was approximately 150 cal/mol for this polymer–solid interface. Below or above this optimum product value r*, the fracture energy of polymer-solid interfaces, G _IC, was less than its optimal value, G _lc*.     

附着力促进剂对光固化金属涂层附着力提升的研究

为了探究附着力促进剂对光固化金属基涂层附着力的影响,本文通过划格法、拉拔法及搭接剪切实验,系统研究了磷酸酯类附着力促进剂、硅烷偶联剂对光固化金属基（低碳钢、铝板）涂层附着力的促进作用。结果表明：磷酸类附着力促进剂能够显著提高光固化金属基（低碳钢、铝板）涂层的附着力,而硅烷偶联剂对光固化金属基（低碳钢、铝板）涂层的附着力无明显提升作用。     

Criteria for blend plant design

Presented at FMB's First International Fertilizer Blending Convention, Brussels, Belgium, June 11–12, 1990.     

Experimental Criteria for Living Polymerizations

Seven experimental criteria for living polymerizations are critically reviewed. The limitations of the use of linear plots of M?_n (or X?;_n) versus conversion and linear plots of the number of polymer chains versus conversion are illustrated by an example of alkyllithium-initiated polymerization of styrene by incremental additions of styrene with deliberate termination (5% per incremental monomer addition). The experimental criteria of using narrow molecular weight distribution and the formation of block copolymers are illustrated with practical examples and size exclusion chromatography data. The use of the terms ‘living polymerization with reversible termination’ and ‘living polymerization with reversible chain transfer’ are proposed.     

Fracture Criteria for Piezoelectric Ceramics

Fracture criteria for piezoelectric materials were investigated. Mode I and mixed mode fracture tests were performed on PZT-4 piezoelectric ceramics to verify the validity of the mechanical strain energy release rate as a fracture criterion. Experimental results indicated that crack extension could be aided or impeded by an electric field, depending on the field direction. Further, the direction of crack extension was studied. A crack closure method, together with finite element analysis, was introduced to calculate the mechanical strain energy release rate. The maximum mechanical strain energy release rate was used to predict fracture loads under combined mechanical and electrical loads. It was found that the mechanical strain energy release rate criterion is superior to other fracture criteria and predicts fracture loads fairly accurately.     

Similarity Criteria for Underwater Explosions

The series of dimensionless parameters for the generalized representation of the space–time parameters of underwater explosions is supplemented taking into account the influence of density and velocity of sound in the liquid on shockwave propagation.     

粘接制动蹄用耐高温胶粘剂及其粘接性

介绍一种新型酚醛－－丁腈并用耐高温高强度单组分浆状结构胶粘剂和组成比例以及固化条件对粘接强度的影响，该胶适用于粘接刹车制动蹄和飞机轻金属结构等。     

The Adhesion Society Award for Excellence in Adhesion Science Sponsored by 3M

The modification of ethylene vinyl acetate copolymers by hydrolysis yields a broad range of new ter-and copolymers with entirely improved chemical and physical properties, especially important for adhesion applications. An infra-red spectroscopic method was developed in order to achieve a fast and accurate identification of their basic parameter, the mol % vinyl-alcohol, which allows characterisation of the new polymers.     

氟涂料用附着力促进树脂

考察了聚三氟氯乙烯涂料和聚四氟乙烯涂料，以及加入附着力促进树脂的氟涂料对几种常用底材的附着力。试验结果表明：加入附着力促进树脂的氟涂料对其综合性能基本上无影响，但可改善涂膜的耐水性和提高其对多种底材的附着力。     

Modeling of Adhesion for Railway Vehicles

This paper describes the development of a mathematical model and application of the numerical results to predict the adhesion forces between wheels and rails. The adhesion force is realized on a small area of a wheel–rail contact. Many factors have an influence on the adhesion process for these surfaces (e.g., environment, pollution, parameters and conditions of railway vehicle service, track, etc.). The paper focuses on different modelling aspects. Experimental investigation on the process of friction in the contact zone was performed. The data obtained were used to create a mathematical model. The adhesion, which is dependent on load from the wheel to the rail, temperature, friction conditions in the contact zone and wheel slip, was calculated. Finally, a quick method to determine the adhesion force between the wheels (wheel pair) of a railway vehicle and rails (rail track) is presented.     

木材用聚氨酯胶粘剂的研制

介绍了聚氨酯胶粘剂的合成过程及不同种类的聚醚、固化剂和木材含水率对胶粘剂性能的影响。     

New and Improved Tests for Adhesion

Three new methods are discussed for measuring the work G_a, required to detach unit area of an adhering material from a substrate. The first is a simple modification of the Outwater double-torsion test for long rectangular plates, bonded together. This method is suitable for evaluating aluminum-epoxy bonds, for example, or the transverse strength of fibrous composites. The second is a pull-off test for long strips adhering to a rigid surface. It seems suitable for adhesive tapes and laminates. The third is a reconsideration of the “blister” test for films and coatings, in which a circular debond at the interface is made to grow by internal pressure. The relation obtained between pull-off force F for a strip, or blow-off pressure P for a layer, takes the unusual form:

F⁴ (or P⁴) ∞ KG³_a

where K is the tensile stiffness of the detaching layer. This dependence arises from the non-linear (cubic) relation between load or pressure and deflection in these configurations. Nevertheless, the product Fθ, where θ is the angle of detachment of a strip, or Py, where y is the height of a “blister”, give direct measures of the strength of adhesion G_a, independent of the stiffness of the adhering material and of the extent of detachment.