Adhesion mechanical aspects

Jones, F.R., Interfacial aspects of glass fibre reinforced plastics. In Jones, F.R. (Ed.), Interfacial Phenomena in Composite Materials. Butterworths, London, 1989, pp. 25-32. Chaudhury, M.K., Gentle, T.M. and Plueddemann, E., Adhesion mechanism of poly(vinyl chloride) to silane primed metal surfaces. J. Adhes. Sci. Technol, 1(1), 29-38 (1987). Gellman, A.J., Naasz, B.M., Schmidt, R.G., Chaudhury, M.K, and Gentle, T.M., Secondary neutral mass spectrometry studies of germanium-silane coupling agent-polymer interphases. J. Adhes. Sci. Technol., 4(7), 597-601 (1990). 

Similarly, Allen, Alsalim and Wake 45,46 determined that alkaline hydrogen peroxide was the best pretreatment for titanium alloys. This pretreatment was found to preferentially etch the P phase, while also undercutting some of the a grains and redepositing needle-like crystals on the P grains. The very rough surfaces that resulted were found to enhance adhesion by mechanical aspects. 

Formation of Metal Oxides Which Promote Mechanical Aspects of Adhesion... 

Additional work must be completed before these hydration inhibitor treatments will be widely used. However, it appears that combined FPL/inhibitor pretreatments have the potential of producing water stable aluminum oxides with structures that promote mechanical aspects of adhesion in a relatively simple manner. Since mechanical adhesion mechanisms are not greatly affected by water, these pretreatments show promise as a means of increasing the durability of metal/polymer adhesion systems in wet environments. 

Kinloch, A. J., Interfacial Fracture Mechanical Aspects of Adhesion Bonded Joints, Review Article, Journal of Adhesion, vol. 10, 1979, p. 193. 

An important aspect of the function of compounded lubricants is to increase the load that can be carried by machinery without catastrophic damage to the rubbing components. Since the typical antiwear additives affect the viscosity of the carrier oil very little, it is not a fluid film effect that is responsible for the load-carrying augmentation. Examination of the various basic wear processes leads to the choice of the adhesive mechanism as the one most likely to respond to the action of boundary or extreme-pressure additives. The type of macroscopically observed severe wear which has this mechanistic process as its primary cause is generally designated as icu i ng (c(S. Chapter 13, Sections 13.4 and 13.6), and it is in this sense, as a description rather than a definition, that the term scuffing is used in the discussion to follow. 

The detailed study of molecular mechanisms involved in adhesion requires an atomistic treatment of the substrate surfaces and their interaction with the organic components contained in the adhesive. Interesting aspects of the substrate-adhesive interaction include the preferential molecular orientation due to the interaction at the surface [1] or the influence of the initial stages of polymer grafting on the stability of polymer/metal interfaces [2]. The structure and composition of the interface can have a decisive effect on the properties of the re-... 

To function as a circuit board, the polymer must be metallized. A key aspect of this technology pertains to the adhesion developed and maintained between the metal and polyetherimide. The adhesion between a metal and a ooivmer can be viewed in terms of ohysical or mechanical adhesion, and chemical adhesion. Mechanical adhesion results from interlocking of the metal and polymer phases due to die creation of re-entrant cavities or macroscopic fissures in the polymer structure. Mechanical adhesion may also result from the presence of fine, shallow pits along the polymer surface. Chemical a esion relates to the formation of chemical bonds between the metal and polymer layers. The chemical interactions can result from actual charge transfer, e.g., ionic or covalent bond formation, van der Waals forces, or electrostatic or acid-base interactions. ... 

A. J. Kinloch, Interfacial fracture mechanical-aspects of adhesive bonded joints, AGARD Lecture Series 102, Wright-Patterson AFB, Dayton, Ohio (Oct. 1979). 

Failure in an adhesive joint can occur in one of two ways (1) adhesive failures that occur at the interfaces between the adhesive and adherends, and (2) cohesive failures, which occur either in the adhesive or in the adherends. The determination of the strength, failure, and reliability of an adhesive joint requires both an understanding of the mechanisms of adhesion and a knowledge of deformation and stresses in the joint. The mechanisms of adhesion are closely related to chemical and physical properties of the adhesive polymers. The deformation and stress states can be determined once the geometry, loading, boundary conditions, and mechanical properties of the constituent materials of the joint are known. The mechanical properties of the adhesive and adherend materials enter the stress analysis via constitutive models, which relate strains, temperature and moisture gradients, and density to stresses and fluxes in the joint. The chemical, physical, and mechanics aspects of the constituent materials enable the formulation of appropriate constitutive models for adhesive joints. The determination of stresses allows the prediction of the strength, failure, and reliability, in a macromechanics sense, of adhesive joints. 

The pharmaceutical literature has discussed the mechanical aspects of the tablet making process but has rarely discussed it from a surface chemistry or adhesion science perspective. In this paper, we discuss a model based on surface chemical principles that can be used to calculate the tensile strength of tablets from constituent components. Specifically, the role of surface free... 

We may now point out a mechanical aspect of the void-filling functions. It may be noted that continuity of the stress tensor, between the two solid phases, is a necessary condition for strong adhesion. When interfacial voids are filled, the regions which would have been weak because of stress concentrations around voids are replaced with regions where there is no discontinuity of the stress tensor. The void-filling function, performed by an adhesive, is often more important than its possession of high shear or tensile strength. 

As the focus will be on the mechanical aspects of adhesives, no attempt will be made to explore the chemical and physical attributes of the adhesives and more information on these matters has been published in comprehensive reviews such as by Adams et al. [ 1 ]. 

Most published evidence on polymer friction led one to believe that the adhesion mechanism can explain many unrelated phenomena provided that the relaxation aspect is taken into account. It appears that as long as polymers are concerned, relaxation controls both adhesion and friction. Thus, a clear demarcation between adhesion and deformation components is unattainable, and many unnecessary arguments about mechanisms can be avoided if relaxation is considered to be the intrinsic property of polymer. 

The solid wear particles from ZDDP films produced in lubricated contacts contain phosphorus, sulfur and zinc from the ZDDP molecule and oxygen mainly from the surrounding air environment. They also have a low iron content. Ex situ examination by XAS, EELS and CEMS of these particles (configuration shown in Fig. 5a) has been carried out to provide local analysis of the iron atoms, since their localized environment in the surface film is of great interest it is related directly to the wear of the steel surface and can also play a key role in the adhesion mechanisms of the film. In order to investigate this aspect, a study was made by XAS (EXAFS plus XANES) of a collection of wear debris from two lubricated tests, with and without ZDDP in the lubricant base, respectively. The processed EXAFS data presented in Fig. 8 show the RDFs of iron atoms (noncorrected phase shifts) in four samples data from the standards, pure crystalline iron and iron oxide have been included for comparison. From this EXAFS study, some important results can be deduced [4] ... 

Surface analysis has made enormous contributions to the field of adhesion science. It enabled investigators to probe fundamental aspects of adhesion such as the composition of anodic oxides on metals, the surface composition of polymers that have been pretreated by etching, the nature of reactions occurring at the interface between a primer and a substrate or between a primer and an adhesive, and the orientation of molecules adsorbed onto substrates. Surface analysis has also enabled adhesion scientists to determine the mechanisms responsible for failure of adhesive bonds, especially after exposure to aggressive environments. The objective of this chapter is to review the principals of surface analysis techniques including attenuated total reflection (ATR) and reflection-absorption (RAIR) infrared spectroscopy. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) and to present examples of the application of each technique to important problems in adhesion science. 

Lackie, J.M., Wilkinson, P.C. (1984). Adhesion and locomotion of neutrophil leukocytes on 2-D substrata and in 3-D matrices. In White Cell Mechanics Basic Clinical Aspects (Meiselman, H.J., Lichtman, M.A., LaCelle, P.L., eds.), pp. 237-254. Alan R. Liss, New York. 

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