The invention provides a novel method for preventing bleeding of a plasticizer or other additive ingredients contained in a shaped article of a vinyl chloride-based resin composition on to the surface of the article by the treatment with low temperature plasma. Different from conventional procedures for the plasma treatment, much improved reliability and reproducibility as well as effectiveness are obtained by subjecting the article to intermittent exposure to the plasma atmosphere instead of continuous exposure. In the inventive method, the overall treatment time is an alternate sequence of exposure times, each being of the length of 0.001 second to 1000 seconds, and repose times, each being also of the length of 0.001 second to 1000 seconds. The gas for the plasma atmosphere is desirably an inorganic gas selected from the gases other than oxygenic gases, halogen containing gases and sulfur containing gases.

A technique has been developed for estimating the hydrogen bonding and London dispersion force components of liquid surface tension and solid surface free energy levels. The technique relies on (a) measuring contact angles generated by sessile drops of liquids on solids and (b) performing calculations based on theories of thermodynamic wetting of solids by liquids. The technique is used to estimate interfacial force components of certain liquids and papers typical of those used in xerographic processing.

Specific reactions for the derivatization of oxygen-containing functional groups in polymer surfaces have been developed in order to improve the precision of analysis by X-ray photoelectron spectroscopy (xps). These have been used to probe the chemical composition of low density polyethylene (ldpe) surface-modified by electrical discharge treatment. Simultaneously the effect of derivatizing particular groups on the auto-adhesive behaviour of these surfaces has been examined. Two independent specific interaction mechanisms have been identified.

The effect and interrelationship between primary (segmental backbone) and secondary (side chain) molecular motions on thrombogenesis, independent of morphological order/disorder, crystallinity, and/or associated water is elucidated using an amorphous hydrophobic polymer of poly-[(trifluoroethoxy) (fluoroalkoxy)phosphazene], PNF. The results indicate that thrombogenesis for an amorphous hydrophobic polymer is sensitive and dependent on the degrees and types of primary and secondary molecular motions at the polymer interface.

The above results are intended to be suggestive rather than definitive. Nevertheless, they strongly support the premise that a cross-fertilization of both concepts and experimental data from the apparently unrelated fields of Lewis acid-base chemistry and adhesion theory can lead to potentially valuable results for both fields, emphasizing again the value of using a generalized acid-base vocabulary in describing the phenomena of chemistry, whatever one's area of specialization.

XPS has been used to elucidate the mechanisms of surface modification of low density polyethylene by electrical (“corona”) discharge treatment and by chromic acid treatment. The use of derivatisation techniques for improving the precision of functional group analysis is described. These techniques also allow the role of specific interactions in adhesion to discharge treated surfaces to be investigated. The role of residual Cr on the adhesion of deposited metal to polymer surfaces is discussed.

A systematic surface fluorination of high-density polyethylene was carried out using CF₄, CF₃H, CF₃Cl, and CF₃Br, in a radio-frequency glow discharge. Based on ESCA and wettability measurements, all of these compounds provided a fluorocarbon layer on high-density polyethylene surface, but the fluorine to carbon ratio and extractability of the films were strongly dependent on the starting materials and the location of the sample specimen in the reactor chamber as well as the duration of the reaction. The results with vertically held, CF₃H-treated samples showed a high level of nonextractable surface fluorination and very little change in wetting properties before and after extraction with CF₂ClCFCl₂.

E.s.c.a. spectra of surface fluorinated polyethylene, poly(vinyl fluoride), and poly(vinylidene fluoride) are reported. Two reaction environments were used in this study: exposure to elemental fluorine and immersion in a glow discharge plasma. The systematic variation of fluorine composition in the polymer phase is shown to have a dramatic effect on the kinetics of the elemental reaction and little effect in the plasma reaction.

The modification of polymer surfaces by gas plasma treatment is reviewed. The two regimes of major interest are radio-frequency at low pressure (about 1 torr) and corona discharge at atmospheric pressure. The reactions produced by plasmas at polymer surfaces are due to both radiation and chemically active species created by electron bombardment. The major changes produced are in wettability, molecular weight, chemical composition, and surface morphology. The mechanisms of plasma polymerization and the properties of polymers produced by this technique are described. Finally, a brief outline is given of the industrial applications of plasma techniques.

Apparatus for the corona discharge treatment of a travelling web such as a plastics or cellulose film comprises a pair of spaced conductors with an associated alternating voltage power supply set at such a distance apart that the possibility of spark or arc discharge is avoided, at least one conductor having mounted thereto an electrode member extending towards the other conductor to define a gap across which a corona discharge can be formed. The electrode member consists of a dielectric material having a dielectric constant of at least 8, preferably at least 80, and may consist of a plate with an edge directed towards the other conductor. Preferably the plate is formed of one or more ceramic tiles based upon a titanium and/or zirconium compound. In another form the electrode member consists of a row of rods or two or more rows of spaced rods in staggered relationship.

The London dispersive component of surface free energy γ_s^d and the nondispersive interactions with polar liquids W I_swⁿ were determined for hydrophilic polymers S, that is, cellulose, poly(vinyl alcohol) (PVA), and poly(methylmethacrylate) (PMMA). On applying the geometric-mean relation $\text{2(γ}{}_{\mathrm{s}}{}^{\mathrm{d}}\text{γ}{}_{\mathrm{w}}{}^{\mathrm{d}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ to the dispersive interaction with W I_sw^d, the γ_s^d values were found to be 30, 29, and 37 erg·cm⁻² for cellulose, PVA, and PMMA, respectively. Each of them is completely independent of the nature of the testing liquids W, indicating that the geometric-mean equation is appropriate for representing the dispersive interaction. On the contrary, such a geometricmean expression is shown to be inapplicable to the nondispersive interactions. It is suggested that Fowkes' approach, in which intermolecular forces are regarded to be dominated by dispersion force interactions and electron donor-acceptor interactions, is more reasonable than the popular approach.

Plastic surfaces are treated with electrical corona discharge in an atmosphere of nitrogen and carbon dioxide. Oxygen is substantially excluded, and is kept at less than 0.1% by volume.

A new approach to qualitatively predicting adhesion at a solid/solid interface is described. It is based on thermodynamic compatibility of the two adhering surfaces, but it overcomes the weaknesses of existing methods by using a full set of contact angle data and by assembling the data to reveal the main features of the set without loss of information. Adhesive performance data to support this approach are presented.

Compounds based on polyolefins may find further use in the footwear industry as solings. However, a significant problem is the poor adhesion obtained with the urethane adhesives currently used. SATRA has recently attempted to develop practical bonding systems for commercial olefinic compounds. The use of flame treatments for polyethylene appeared to be a possible method of improving compatibility between the adhesive and substrate if an isocyanate is present at the interface. Polypropylene does not respond to the flame treatment but reasonable bonds have been obtained after surface oxidation or by using a sensitiser in conjunction with UV irradiation. The use of dual compound moulding is described as a possible alternative means of obtaining adequate adhesion to difficult surfaces.

This paper presents and discusses particle behavior at solidification fronts from a thermodynamic point of view. Engulfing or rejection of particles embedded in a melt by solidification fronts depends on whether such quantities as the free energy of adhesion or of engulfing are positive or negative. As the relevant energy balances contain solid‐liquid interfacial tensions which are difficult to determine, these studies may also be viewed as tests for the validity of such data and the underlying theories used to determine them. In this paper, solid‐liquid interfacial tensions are derived from contact angle data and the equation of state approach for interfacial tensions [Neumann et al., J. Colloid Interface Sci. 49, 291 (1974)]. The thermodynamic predictions obtained in this way for approximately 60 systems agree very well with microscopic observations with particles in the range of 10–200 mm in diameter.

The influence of substrate roughness on wettability has been investigated at room and high temperatures using sixteen material combinations, mostly liquid metals and solid ceramics but also water, glycerol and solid nickel. The contact angles assumed by both wetting and non-wetting drops of all but two material combinations increased linearly with the relative steepness of the surface features, the effect being less for experiments conducted at high temperatures. In contrast, the contact angles of good wetting drops of glycerol and exceptionally good wetting drops of Easy-flo decreased when their silica and nickel substrates were roughened. Similarly, contact angles of both wetting and non-wetting drops were decreased by ultrasonic vibration. The experimental data can best be interpreted in terms of the metastable equilibrium configuration models in which an advancing liquid front has to overcome energy barriers associated with surface features. This occurs more readily if these barriers are small relative to the energy of the liquid which our data suggest can be equated with the enthalpy of the liquid. This interpretation enables the effects of substrate roughness at one temperature or with one liquid to be used to predict behaviour at other temperatures and with other liquids.

Adhesion to polyethylene and polypropylene is a complex subject requiring understanding of (a) the poor adhesive characteristics of these polymers; (b) the superior performance following certain pretreatments and (c) the nature of the changes brought about by these pretreatments and the mechanisms involved. This review discusses work on these topics and examines the impact of recent data resulting from the application of surface analytical techniques. The roles of ‘weak boundary layers’, surface energy and wettability and specific interactions are discussed in some detail.

The paper presents a theory on determining the dynamic surface tension using two methods: the drop volume method and the maximum bubble pressure method.

Surface energies of solids can be estimated using contact angles of liquids of known surface tension and susceptibilities for polar or acid-base interactions. Interfacial tensions and work of adhesion can be calculated using these estimated energies. There are three circumstances in which performance or bond strengths are related directly to surface energies: when separation occurs interfacially, when interfaces are not completely wetted, and when third phases are present at the interface.

The interfaces formed by evaporating copper, nickel, and chromium layers on polystyrene, polyvinyl alcohol, polyethylene oxide, polyvinyl methyl ether, polyvinyl acetate, and polymethyl methacrylate have been studied with x‐ray photoemission spectroscopy (XPS). The adhesion strengths of the metal films to the polymers were measured by a tensile‐pull test. At submonolayer coverages of the metals, the peak positions and widths of the metallic electron core levels measured with XPS vary significantly from one polymer substrate to another. Most of these variations can be accounted for in terms of changes in the atomic and extra‐atomic relaxation energies during the photoemission process. Much of this change is brought about when the metal atom deposited on an oxygen‐containing polymer interacts with the substrate oxygen and forms a metal‐oxygen‐polymer complex. The presence of this complex is verified by changes in the photoemission lineshapes of the substrate carbon and oxygen atoms. The XPS signatures of these various complexes are quite similar and suggest that they are chelate‐like complexes. The adhesion strength of any metal on an oxygen‐containing polymer is greater than on the oxygen‐free polystyrene. In general, the increased adhesion strength correlates with the presence of the metal‐oxygen chelate complexes.

The contact angle of a water droplet on the surface of a solid polymer or hydrogel (water-swollen three-dimensional network) depends on whether a hydrophilic moiety of the polymer molecule is oriented towards the air interface or towards the bulk of the solid, but not on the hydrophilicity of the molecule. Therefore, the short-range rotational mobility of a polymer molecule has a major influence on the apparent hydrophilicity of a polymer surface as measured by the contact angle of water. By the came principle, the abnormally large hysteresis effect observed in advancing and receding contact angles of water on some polymer surfaces can be attributed to the reorientation of hydrophilic moieties of polymer molecules at the surface. These factors are demonstrated by selected polymer surfaces with different degrees of mobility at the polymer-air interface.

A new method of quickly and precisely measuring the surface tension of liquids and solutions is described. Utilizing the fact that the size of the bubbles formed from a gas flowing out of a nozzle is dependent on the nozzle diameter and the surface tension of the liquid used, the surface tension of a liquid can be determined by simply counting the number of bubbles formed from a gas flowing out at a constant flow rate or by measuring the period of bubble formation. The expected accuracy of the method is below 0.1% of variance. An evident correlation between the period of bubble formation and the surface tension was shown with several kinds of liquids which differ in surface tension. Changes in surface tension with varied degree of neutralization were determined in an aqueous solution of polyacrylic acid (PAA), 20-30 points of measurement with an accuracy of about 0.1% could be easily obtained within one hour.

Starting from a comparative assessment of the outstanding works on the ring method (du Noüy) for the determination of the surface tension of liquids and its solutions it is shown that the application of this method to surfactant solutions can lead to substantial errors if one follows conventional conditions. These errors are mainly connected with so far unknown phenomena occurring during the raising of the ring and concerning the influence of the hydrophilic vessel wall above the solution level and the stretching of the solution surface. This is demonstrated quantitatively with surfactant solutions of different kind and concentration. These effects can be explained theoretically very simply by introducing certain assumptions on the behaviour of a surfactant adsorption layer on the inner vessel wall. Conditions leading to the elimination of these errors are given, thus enabling the application of the ring method to the determination of the surface tension of surfactant solutions.