ISSN:0032-3888    

DOI:10.1002/pen.760170702

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe change in retention mechanism at the glass transition temperature (Tg) of a polymer stationary phase from surface adsorption belowTgto bulk sorption aboveTgallows for a separate determination of the magnitude of the solute interaction with both the bulk and the surface of the polymer. As a result, the limiting surface tension of the polymer‐probe solution can be obtained from the corresponding partition coefficients. Examples of such determinations are given for several polymer‐solute syst

ISSN:0032-3888    

DOI:10.1002/pen.760170703

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractAn ovrerview of a new theory for describing interfacial phenomena in layered composites is presented. Relations are given for determining the adhesion of thin brittle films on flexible substrates, for determining residual strains resulting from drying solvent cast films, and for calculating thermoelastic strains in unsymmetric laminates. An experimental technique to measure the adhesion is discussed and values are obtained using experimental data. Residual strains are also calculated using the derived relations and solvent d in data.

ISSN:0032-3888    

DOI:10.1002/pen.760170704

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe, nature of polymer surfaces has received increasing attention as the use of these materials, in a variety of forms, increases yearly. Modifications of polymer surfaces for adhesion, friction, and diffusion oriented appiications have necessitated a careful analysis of the surfade region morphology (surface physics) and chemical properties of the surface layer (surface chemistry). The behavior of composite structures has involved the discipline of classical fracture mechanics. The orientation of polymeric species or additives which migrate to the interface may modify the wetting characteristics and, most certainly, the frictional properties in addition to the diffusion of penetrant species beyond the boundary layer. The above topics are discussed within the framework of recent analytical and theoretical developments in surface science. The findings of these recent studies have facilitated many exciting technological advances.

ISSN:0032-3888    

DOI:10.1002/pen.760170705

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractSuccessful modification of the surface properties of solid polymers was obtained by the adsorption of appropriate partially fluorinated oligomers at polymer/air and polymer/substrate inter faces during the formation of these interfaces. These additives, in concentrations of 0.25 percent, effectively lowered the critical surface tension of wetting, γc, of such polymers as polystyrene, poly(methylmethacrylate), and poly(vinylidene chloride) copolymers by as much as 26 dyn/cm. The obtained low γcvalues of 14 dyn/cm correspond to surfaces containing closely packed CF3and CF2groups. Adhesion of additive‐containing polymer films to various substrates was demonstrated to be a function of additive diffusion to the polymer/substrate interface, its subsequent adsorption and molecular orientation at that interface, and the surface energy of the substrate. The fluorinated additive molecules also have the advantage of being sufficiently mobile in the solidified polymer to reach and repair the interfa

ISSN:0032-3888    

DOI:10.1002/pen.760170706

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe shear strength of bonds between isotactic polypropylene and cellophane, formed under standard conditions, has beer studied as a function of cooling rates, following bond formation, and after ageing at temperatures up to 90°C. Rapid cooling produced cohesively failing bonds with shear strengths above 20 kg/em2. Weak, adhesively failing joints were produced under slow‐cooling conditions. Strong bonds deteriorated when joints were aged at temperatures above 50°C, but further improvement in bond strength was observed upon ageing at lower temperatures. Experimental observations were consistent with the development of smectic structure in the polypropylene upon rapid cooling; a tendency for transcrystallization in slow‐cooled joints was offset by the presence of weak boundary layers in the interface. Ageing produced further development of weak boundary layers and a transition from smectic to monoclinic crystallization in polypropylene. At higher ageing temperatures, the former effect seemed dominant; at lower temperatures, the structural change was assumed responsible for the observed improvement in bond str

ISSN:0032-3888    

DOI:10.1002/pen.760170707

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractA review is given of the mechanics of peeling rupture of an adhesive joint, consisting of a flexible adhering strip peled away from a layer of adhesive. Attention is drawn to a number of anomalous results that cannot be accounted for solely, in terms of the thermodynamic work of formation of two new surfaces. The work of detachment is found to be generally much larger than the theoretically‐predicted amount. Moreover, the value obtained is greater for thicker layers of adhesive, and for detachment at a peel angle of 180° rather than at 90°. Also, it is found to increase with increasing thickness of the adhering strip, passing through a maximum value in some cases and then decreasing as the strip thickness is increased still further. All of these effects are attributed to dissipative processes, for example, plastic yielding, in one or both of the adhering layers as they are peeled apart. Some quantitative relationships are given for the additional peel forces arising from plastic yielding of the adherend or the adhes

ISSN:0032-3888    

DOI:10.1002/pen.760170708

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe role of the interface in adherend‐adherate combinations and in the strength of adhesive joints has been examined. For the former systems, practical adhesion (as determined experimentally, for example, by peel, tensile, or shear strengths) is a function of basic adhesion (determined by intermolecular, interactions such as van der Waals, electrostatic, or valence type forces) and many other factors. Adhesive joint strength depends pends upon the mechanical response of the various phases involved; however, the data in the literature on such strengths suggest the importance of surface chemical and energetic factors. Various such criteria, including, wetting, thermodynamic work of adhesionWA, and interfacial tension,ySL, for maximum joint strengths and the conditions which optimize these criteria are discussed. The testing of these factors against the literature data on adhesive joint strengths shows that the interfacial tension between the substrate and the adhesive (ysL) is the most important criterion; the lower theySL, the higher the joint strength. In the case of adherend‐adherate systems, (e.g., metallized polymers), basic adhesion can be improved by chemical bonding or electrostatic contributions, and this improvement may or may not be reflected in improved practical adhesion. Examples are cited where an increase in basic adhesion does culminate in improved practical adhesion. On the other hand, practical adhesion does not always correlate with basic adhesion due to the influence of other fact

ISSN:0032-3888    

DOI:10.1002/pen.760170709

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThis paper discusses a recently developed surface energetics criterion for adhesive bonding and fracture and its applications in such diverse areas as structural adhesive bonding, fiber reinforced composites, biomaterials development, and lithographic printing. The theoretical relations describe systematic methods for the surface energy analysis of solid adhesive and adherend surfaces. The surface tension properties for the adhesive and adherend can then be introduced into a modified Griffith fracture mechanics relation to obtain predictions of bond strength under varied conditions of liquid or gas phase immersion such as water and dry air.

ISSN:0032-3888    

DOI:10.1002/pen.760170710

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY

摘要:

AbstractThe development of ultraviolet radiation technology to cure or photopolymerize acrylic unsaturated monomers, oligomers, and polymers into tight network structures introduces several adhesion problems that can be related to or associated with interfacial polymer‐substrate failure. This paper discusses network formation, polymer‐interfacial growth association and failure as a function of the following variables: light intensity (effect on sol/gel conversion), photoinitiator (structurereactivity as a function of conversion), polymer shrinkage, and substrate wetting. The results of this study show that all of the above variables interact in a composite fashion to influence the final properties of the ultraviolet cured coati

ISSN:0032-3888    

DOI:10.1002/pen.760170711

出版商:Society of Plastics Engineers, Inc.    

年代:1977

数据来源: WILEY