Adhesion, practical application

The performance of the classifier has been verified using a number of practical applications, such as civil engineering [3], inspection of aerospace composite structures, ball bearings and aircraft multi-layer structures. Here we present shortly some results, focusing on detection of disbonds in adhesively joint multi-layer aerospace structures using Fokker Bond Tester resonance instrument, details can be found in [1]. 

The study of acid-base interaction is an important branch of interfacial science. These interactions are widely exploited in several practical applications such as adhesion and adsorption processes. Most of the current studies in this area are based on calorimetric studies or wetting measurements or peel test measurements. While these studies have been instrumental in the understanding of these interfacial interactions, to a certain extent the interpretation of the results of these studies has been largely empirical. The recent advances in the theory and experiments of contact mechanics could be potentially employed to better understand and measure the molecular level acid-base interactions. One of the following two experimental procedures could be utilized (1) Polymers with different levels of acidic and basic chemical constitution can be coated on to elastomeric caps, as described in Section 4.2.1, and the adhesion between these layers can be measured using the JKR technique and Eqs. 11 or 30 as appropriate. For example, poly(p-amino styrene) and poly(p-hydroxy carbonyl styrene) can be coated on to PDMS-ox, and be used as acidic and basic surfaces, respectively, to study the acid-base interactions. (2) Another approach is to graft acidic or basic macromers onto a weakly crosslinked polyisoprene or polybutadiene elastomeric networks, and use these elastomeric networks in the JKR studies as described in Section 4.2.1. 

Polymer adsorption is important in the flocculation and stabilization of colloidal sols and has been reviewed by Vincent et al. (1) and Tadros (2). Polyvinyl alcohol (PVA) has been used in these studies because of its practical application in textiles, adhesives, and coatings. The adsorption of PVA has been studied on silver iodide by Fleer (3) and Koopal (4), and on polystyrene (PS) latex particles by Garvey (5). The adsorption isotherms reported by these workers extend up to 600 ppm PVA. The adsorption at... 

This review will highlight the interrelationships between basic photopolymer science and practical applications of this technology. Each application of photopolymer technology can be described in terms of three primary descriptors the mode of exposure, the mechanism of the photopolymer reaction employed and the visualization method used. Using this foundation, the widely diverse applications of photopolymer technology to electronic materials, printing materials, optical and electro-optical materials, the fabrication of devices and polymeric materials, adhesives and coating materials will be discussed. 

Zisman discovered that there is a critical surface tension characteristic of low-energy solids, such as plastics and waxes. Liquids ihat have a lower surface tension than the solid will spread on that solid, while liquids with a higher surface tension will not spread. Examples of critical surface tension values for plastic solids in dynes per cm are "Teflon/ 18 polyethylene, 31 polyethylene terephthalate, 43 and nylon, 42-46. As one indication of the way this information can be used in practical applications, one can consider the bonding of nylon to polyethylene. If nylon were applied as a melt to polyethylene, it would not wet the lower-energy polyethylene surface and adhesion would be poor. However, molten polyethylene would spread readily over solid nylon to provide a strong bond. 

Block copolymers are widely used industrially. In the solid and rubbery states they are used as thermoplastic elastomers, with applications such as impact modification, compatibilization and pressure-sensitive adhesion. In solution, their surfactant properties are exploited in foams, oil additives, solubilizers, thickeners and dispersion agents to name a few. Particularly useful reviews of applications of block copolymers in the solid state are contained in the two books edited by Goodman (1982,1985) and the review article by Riess etal. (1985). The applications of block copolymers in solution have been summarized by Schmolka (1991) and Nace (1996). This book is concerned with the physics underlying the practical applications of block copolymers. Both structural and dynamical properties are considered for melts, solids, dilute solutions and concentrated solutions. The book is organized such that each of these states is considered in a separate chapter. 

Abstract—When K. L. Mittal asked me to provide a historical account of the applications of silane coupling agents in adhesion. I decided to write in the form of a personal account of my last 45 years in this line of study. No attempt is made to make the history comprehensive, or to recognize the host of other researchers who have contributed to our understanding of adhesion across an interface of dissimilar materials. It has been an immensely interesting area of study with many practical applications in composites and bonded structures. 

The practical application of this study lies in the beneficial effect on composite properties observed as a result of toughening these resin systems. These data were reported at the 1970 SPI Conference (9). Current work on the effect of this type of modification on adhesives will be the subject of a future report. 

Elemental sodium, as well as other alkali metals, reacts with perfluorocarbon polymers by removing fluorine from them. This reaction has a practical application for improving surface wettability and adhesive bonding of perfluorocarbon polymers to other substrates.57... 

Polymer solutions and dispersions find many practical applications. We can cast films from some polymers, and we use many others to form coatings. Coatings can be produced from either solutions or dispersions such as polymer emulsions (latexes). Examples include paint, varnish, textile finishes, adhesives, and floor waxes. Other useful latex products are latex gloves, condoms, and balloons. 

There are two categories of common tests for adhesives fundamental property tests and end-use tests. End-use tests, such as peel and shear, are those that try to simulate the type of loading and service conditions to which a joint will be subjected. These tests are relatively straightforward, but experience is required to establish the correct sample type and testing procedures, judge the reliability of the resulting data, and interpret the results and apply them to a practical application. 

There are several analytical tools that provide methods of extrapolating test data. One of these tools is the Williams, Landel, Ferry (WLF) transformation.14 This method uses the principle that the work expended in deforming a flexible adhesive is a major component of the overall practical work of adhesion. The materials used as flexible adhesives are usually viscoelastic polymers. As such, the force of separation is highly dependent on their viscoelastic nature and is, therefore, rate- and temperature-dependent. Test data, taken as a function of rate and temperature, can be expressed in the form of master curves obtained by WLF transformation. This offers the possibility of studying adhesive behavior over a sufficient range of temperatures and rates for most practical applications. Fligh rates of strain may be simulated by testing at lower rates of strain and lower temperatures. 

D 5999 D 6004 D 6005 D 6105 Test Method for Noninterference of Adhesives in Repulping Test Method for Determining Adhesive Shear Strength of Carpet Adhesives Test Method for Determining Slump Resistance of Carpet Adhesives Practice for Application of Electrical Discharge Surface Treatment (Activation) of Plastics for Adhesive Bonding... 

Surface and interfacial energy are important because of their controlling influence on such practical applications as spinning, polymer adhesion, and stability of dispersions and wetting of solids by liquids. 

The use of SSL or lignosulphonates in other polymeric adhesive systems has also been examined [e.g., with polyacrylamide, proteins/aldehydes, polyethylene oxide, polyethylene imine, epoxides, melamine, styrene oxide, polyisocyanates (55)]. So far, these procedures, for different reasons, have not led to any major practical application (36). It would, however, be interesting to reexamine some of these processes using not crude spent sulphite liquors, but instead those purified by membrane filtration. 

Problems and facts that in the author s personal experience arise in the industrial application of tannin-based adhesives for timber sometimes indicate lack of correspondence with laboratory practice and results. These are often problems related to unusual characteristics of the adhesive itself, or of its application technique, which could not be noticed during research under laboratory conditions, but the existence of which could easily jeopardize successful implementation of laboratory technology into industrial practice. Correcting the credibility gap between research focus and industrial usage is seen as a critical step toward market expansion for these new products. Important considerations are consistency of tannins, extracts and adhesives properties due to the natural raw material variability formulation in cold-setting adhesives and application conditions (such as wood moisture and adhesive-content or pressing time) in particleboard adhesives. These problems have been overcome in use of wattle tannin-based adhesives as shown by a visual comparison of tannin-, phenolic-, and melamine-bonded particleboards exposed to the weather for 15 years and the growing use of tannin-based adhesives in other countries. 

Several chapters also demonstrate the use of smaller molecular-weight carbohydrates (i.e., monomers) in adhesives. Tony Conner and his colleagues (Chapter 25) explore the partial replacement of phenol-formaldehyde adhesives used to bond wood with various wood-derived carbohydrates. A1 Christiansen (Chapter 26) and Joe Karchesy and his coworkers (Chapter 27) investigate the very complicated chemistry and the practical application of adhesives based on the reaction of a carbohydrate with urea and phenol. Tito Viswanathan (Chapter 28) describes his attempts to utilize a very large carbohydrate waste stream, whey permeates from the processing of cheese, for the production of wood adhesives. 

Thus, recognition of the characteristic internal stress buildup in a plasma polymer is important for estimating the upper limit of thickness of a plasma polymer for a practical application. Poor results with respect to such parameters as adhesion and barrier characteristics are often due to the application of too thick a plasma polymer layer. The tighter the network of plasma polymer, the higher is the internal stress. Consequently, the tighter the structure, the thinner is the maximal thickness... 

Since it was observed that fluorine contamination was a possibility and had potentially detrimental effects as described in Chapter 10, the excellent primer adhesion achieved with Tfs/(Ar) and Tcs/(Ar), shown in Table 31.3, has significant importance in the practical application of the plasma technique without any of the potentially deleterious effects of fluorine-based systems. Argon plasma treatments on both flow system TMS (Tfs) and closed system TMS (Tcs) polymers were then investigated as an additional system modification that could provide strong adhesion without the incorporation of fluorine-containing monomers in the quest to produce chromate-free coatings systems. 

DC cathodic polymerization of TMS mixed with argon improved the primer adhesion performance of the closed system TMS plasma polymers. Moreover, the addition of a certain amount of argon into the TMS plasma system further increased the plasma coating quality, reflected in the increase in refractive indices. Based on the higher compatibility with the IVD process, the excellent adhesion performance, and the benefit of one process combining TMS plasma polymerization and the postdeposition plasma treatment, DC cathodic polymerization of TMS mixed with argon in a closed system is being considered as a more realistic and favorable approach in practical applications. 

Other homopolymers of olefins are used in practice, a larger side chain typically leading to materials adequate to be used in adhesives, wax coatings, and elastomers. More frequently, practical applications are known for the copolymers of these compounds with ethylene or in synthetic rubbers with butadiene or with isoprene. The decomposition products of some of the homopolymeric olefins when heated in an inert atmosphere are indicated in Table 6.1.12. 

---