Unprinted, unsized, and sized security papers (SP) were treated under SiCl₄−, O₂−, and CF₄-cold plasma conditions. The plasma treatments were carried out in a stainless steel, parallel plate RF (30 kHz) reactor. The influence of plasma parameters, such as RF power, pressure, and treatment time, on the surface properties of plasma-modified security paper was examined. The newly gained surface characteristics were evaluated by Wilhelmy wettability measurements, x-ray photoelectron spectroscopy (ESCA), and scanning electron microscopy (SEM). Statistical experimental designs were used to understand the interactive effects of the plasma parameters. It was found that short treatment times and low RF power values produced the highest wettability with both SiCl₄ and O₂ plasmas regardless of the sizing. Printing and durability characteristics of the plasma-treated substrates were equivalent or superior to the standard samples. Mechanisms of plasma-induced surface modifications are discussed for the paper substrates.

Effects of flame treatment on polyethylene (PE) surfaces have been studied using contact-angle measurements, attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), and an adhesion test. A significantly higher level of surface oxidation was induced by flame treatment on PE than on polypropylene (PP) under a given set of conditions, and unlike the case of PP the oxidation of PE is not confined to the XPS sampling depth on the polymer surface even for a mild flame treatment. High-energy resolution XPS has revealed several different functionalities on the surface and ATR-FTIR has clearly detected the peak at 1715 cm–1 which can be attributed to C[double bond, length as m-dash]O groups. Large contact-angle hysteresis was obtained and was attributed to chemical heterogeneity on the surface. Good adhesion with an epoxy adhesive has been obtained after flame treatment.

The increasing use of polymeric materials in high technological fields, such as automotive, has forced the need to overcome some of their limitations by means of innovative processing. In the automobile industry a complex and critical process is used in order to enhance both wettability and adhesive properties of polypropylene bumper surfaces. Cold plasma treatment represents an efficient, clean and economic alternative to activate polymeric surfaces.

The present work deals with air cold plasma treatment of polypropylene surfaces. Particularly, the influence of AC electrical discharge cold plasma parameters on wettability and adhesion of polymeric surfaces was studied. Also, the nature of the relationship between wettability and adhesion was investigated. Owing to the complexity of plasma–workpiece interaction, an experimental approach was followed. A set of process variables (voltage, time and air flow rate) was identified and used to conduct some experimental tests on the basis of design of experiment techniques. The experimental results show that the proposed plasma process may considerably increase polypropylene wettability and adhesion properties. These outcomes represent the first step in trying to optimise the polymeric adhesion by means of this non-conventional manufacturing process.

Results from x-ray photoelectron spectroscopy (XPS or ESCA), low-energy ion scattering spectrometry (LEIS or ISS); and Fourier transform infrared spectroscopy (FTIR) analyses are presented for unmodified and modified poly (methylmethacrylate) (PMMA) polymer films. Analysis of the unmodified PMMA polymers (isotactic, syndiotactic, and atactic) via ESCA, ISS, and FTIR, established the surface composition, bonding, and functionality before the modification was employed. An rf-plasma glow discharge created from an Ar/H₂gas mixture at different exposure times and power levels was used to treat the polymer surface. Subsequent ESCA, ISS, and FTIR analyses of these modified PMMA's show the effects of surface modification in terms of a model of structural differences, over a limited depth (50–100 Å). The composition and functionality changes of the resulting surfaces are discussed with respect to proposed mechanisms of the plasma reaction and differences in tacticity of the reactant. A two-step reaction mechanism involving reactive decarboxylation/reduction followed by H₂O adsorption is proposed to understand the spectroscopic results.

Results from the x-ray photoelectron spectroscopy (XPS or ESCA), ion scattering spectroscopy (ISS or LEIS), and Fourier transform infrared spectrometry (FTIR) analyses are presented for unmodified and modified poly (methylmethacrylate)/poly (methacrylic acid) (PMMA/PMAA) copolymer films. Analyses of the unmodified PMMA/PMAA copolymer series, via ESCA, ISS, and FTIR, established the surface composition and functionality of the PMMA/PMAA copolymers before the H₂O/Ar rf-plasma treatment was employed. The ESCA, ISS, and FTIR analysis of these modified PMMA/PMAA copolymers show that surface modification over a limited depth (50–200 Å) has occurred. The composition, bonding, and functionality changes of the surfaces are discussed. A two-step modification mechanism (surface reduction of the PMMA/PMAA copolymer followed by H₂O adsorption) is proposed to interpret the spectroscopic results.

Ar⁺1 ion irradiation on a polycarbonate (PC) surface was carried out in an oxygen environment in order to investigate the effects of surface chemical reaction, surface morphology, and surface energy on wettability of PC. Doses of Ar⁺ ion were changed from 5 × 10¹⁴ to 5 × 10¹⁶ at 1 keV ion beam energy by a broad ion beam source. Contact angle of PC was not reduced much by Ar⁺ ion irradiation without flowing oxygen gas, but decreased significantly as Ar⁺ ion was irradiated with flowing 4 sccm (ml/min) oxygen gas and showed a minimum of 12° to water and 5° to formamide. A newly formed polar group was observed on the modified PC surface by Ar⁺ ion irradiation with flowing oxygen gas, and it increased the PC surface energy. On the basis of x-ray photoelectron spectroscopy analysis, the formed polar group was identified as a hydrophilic CO bond (carbonyl group). In atomic force microscopy (AFM) study, the root mean square of surface roughness was changed from 14 Å to 22–27 Å by Ar⁺ ion irradiation without flowing oxygen gas and 26–30 Å by Ar⁺ ion irradiation with flowing 4 sccm oxygen gas. It was found that wettability of the modified PC surface was not greatly dependent on the surface morphology, but on an amount of hydrophilic group formed on the surface in the ion beam process.

Ion irradiation with various oxygen flow rates has been carried out to improve the wettability of polymethylmethacrylate (PMMA) to water and to enhance the adhesion between Al and the polymer. Ar+ ion and oxygen ion were irradiated on the polymer, and amounts of ions were changed from 5 × 1014 Ar+/cm2 to 5 × 1016 Ar+/cm2 by a broad ion beam source. Oxygen gas from 0 ml/min to 7 ml/min was flowed near the polymer surface during the ion irradiation, and the energy of ions was changed from 500 eV to 1500 eV. The wetting angle was reduced from 68° to 49° with the Ar+ ion irradiation only at 1 keV energy, to 43° with the oxygen ion irradiation, and dropped to 8° with Ar+ ion irradiation with flowing 4 ml/min oxygen gas near the polymer surface. Changes of wetting angle with oxygen gas and Ar+ ion irradiation were explained by a two-step chemical reaction among polymer matrix, energetic ions, and oxygen gas. The effects of Ar+ ion and oxygen ion irradiation were explained by considering formation of hydrophilic groups due to a reaction between irradiated polymer chain by energetic ion irradiation and blown oxygen gas, and enhanced adhesion between Al and PMMA was explained by the formation of electron acceptor groups in polymer and electron donors in metal, and by the chemical reaction in the interface between irradiated polymer surface and deposited metal.

Improving wettability of the polycarbonate (PC) surface to triple distilled water has been carried out by Ar+ ion irradiation with blowing oxygen gas. The amount of Ar+ was changed from 1014 to 5 × 1016 ions/cm2 at 1 keV energy by a Kaufman-type ion source. Contact angle of the water to PC has been reduced from 78° to 50° with Ar+ irradiation, and to 12° with Ar+ irradiation in various vacuum pressures adjusted by oxygen gas flow rate (0-4 sccm). Strong O-H stretching vibration peaks at about 3370 cm−1 on FT-IR spectra of the polymer appeared after the surface treatments, and the wetting angle of the treated PC was returned to its value (78°) when the PC was exposed in air environment. The minimum contact angles were maintained with the same value when the irradiated polymers were kept in dilute HCl solution. The improved wettability and surface chemical reaction by Ar+ ion irradiation with oxygen was explained by the formation of a hydrophilic functional group. Enhanced adhesion between aluminum and PC was confirmed by the scotch tape test, and was discussed with relation between the hydrophilic group on the polymer surface and the deposited metal.

Aramid and extended-chain polyethylene fibres have been treated in ammonia and oxygen plasmas in order to enhance adhesion to vinylester resins and thereby improve fibre/resin interfacial properties in composites made from these materials. For both aramid/vinylester and extended-chain polyethylene/vinylester composites, the plasma treatments result in significant improvements in interlaminar shear strength and flexural strength. Extended-chain polyethylene/vinylester composites also exhibit increased flexural modulus. Scanning electron and optical microscopic observations have been used to examine the microscopic basis for these results, which are compared with results previously obtained for aramid/epoxy and extended-chain polyethylene/epoxy composites. It is concluded that the increased interlaminar shear and flexural properties of vinylester matrix composites are due to improved wetting of the surface-treated fibres by the vinylester resin, rather than covalent chemical bonding.

A study of the effects of flame treatments on a high-impact polypropylene has been performed. Both physico-chemical and mechanical properties have been investigated. The surface chemical composition has been determined by XPS, while the surface tension and the polarity were obtained through contact angle measurements. A remarkable agreement in the behaviour of chemical composition and polarity has been found, emphasizing the role of carbonyl and carboxyl groups. The adhesion of treated and untreated samples to paint coatings hua been mechanically tested. The force of adhesion remains quite constant after the first flame treatment. This suggests the importance of chemical interactions of the coating with the first layers of the polymer.

Static secondary ion mass spectroscopy (fast atom bombardment mass spectroscopy), (SIMS (FABMS)) and Fourier transform infrared-photo-acoustic spectroscopy (FTIR-PAS) studies have been performed on samples of polypropylene subjected to different numbers of flame treatments. SIMS spectra allowed us to identify unambiguously the site of oxidation in the methyl pendant groups, because of the striking decrease in the intensity of the methyl fragment in positive-ion spectra. The behaviour of the surface concentrations of hydroxyl, formyl and carboxyl groups as a function of the number of flame treatments has also been observed, leading us to an hypothesis supporting the effectiveness of hydroxyl groups in promoting paint adhesion. FTIR-PAS spectra did not show evident changes on passing from untreated to flame-treated samples. This negative evidence is also important: it implies a limited depth of oxidation. In the light of previous XPS results and FTIR-PAS characteristics (thickness of the observed layer and sensitivity) we suggest a depth of oxidation of some 10 to 20 nm.

Previously published pull-out adhesion results have been substantiated by more extensive studies of chemical and plasma treatment. Particular attention has been paid to the affect of geometrical variables on the values of adhesion obtained. The effect of strain rate has also been examined. Most of the results can be understood on a semi-quantitative basis by a simple extension of lap joint theory.

X-ray photoelectron spectroscopy showed that a normal flame treatment caused a high level of oxidation in low-density polyethylene. 0.02% of the antioxidant 2,6-ditertbuty-p-cresol did not reduce the degree of oxidation or the level of adhesion in contrast to the extrusion of low-density polyethylene. It is estimated that the depth of oxidation is between 40 and 90 Å which is much less than for a moderate chromic acid treatment or with extrusion. There were no significant changes in the XP-spectra or adhesion levels of flame treated samples after 12 months.

The interfacial adhesion of ultrahigh-modulus polyethylene (UHMPE) fibre–vinylester composites was improved by the oxygen plasma treatment of the UHMPE fibre. The chemical functional group formations on the UHMPE fibre surface by oxygen plasma treatment were analysed using diffuse reflectance Fourier transform infrared spectroscopy and the morphological changes of the UHMPE fibre surface by plasma etching were observed by scanning electron microscopy. The wettability enhancement by the chemical functional group formation and the mechanical interlocking due to the micropits were important factors in improving the interfacial adhesion of the UHMPE fibre–vinylester composites by oxygen plasma treatment. In order to investigate the relative importance of the two factors, wettability enhancement and mechanical interlocking, in the improved interfacial adhesion of the UHMPE fibre–vinylester composites, nitrogen plasma treatment was also performed. Nitrogen plasma treatment of the UHMPE fibre was proved to be effective in the formation of the micropittings and ineffective in the chemical functional group formation in comparison with the oxygen plasma treatment. The interlaminar shear strengths of the nitrogen-plasma-treated UHMPE fibre–vinylester composites showed almost the same value as those of the oxygen-plasma-treated UHMPE fibre–vinylester composites. The wettability enhancement and mechanical interlocking are important in the improvement of interfacial adhesion of UHMPE fibre–vinylester composites by plasma treatment and mechanical interlocking seems to be more important.

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.

In the present paper, the following topics are reviewed in detail: (a) the available adhesives, as well as their recent advances, (b) thermodynamic factors affecting the surface pretreatments including adhesion theories, wettability, surface energy, (c) bonding mechanisms in the adhesive joints, (d) surface pretreatment methods for the adhesively bonded joints, and as well as their recent advances, and (e) combined effects of surface pretreatments and environmental conditions on the joint durability and performance. Surface pretreatment is, perhaps, the most important process step governing the quality of an adhesively bonded joint. An adhesive is defined as a polymeric substance with viscoelastic behavior, capable of holding adherends together by surface attachment to produce a joint with a high shear strength. Adhesive bonding is the most suitable method of joining both for metallic and non-metallic structures where strength, stiffness and fatigue life must be maximized at a minimum weight. Polymeric adhesives may be used to join a large variety of materials combinations including metal-metal, metal-plastic, metal-composite, composite-composite, plastic-plastic, metal-ceramic systems. Wetting and adhesion are also studied in some detail in the present paper since the successful surface pretreatments of the adherends for the short- and long-term durability and performance of the adhesive joints mostly depend on these factors. Wetting of the adherends by the adhesive is critical to the formation of secondary bonds in the adsorption theory. It has been theoretically verified that for complete wetting (i.e., for a contact angle equal to zero), the surface energy of the adhesive must be lower than the surface energy of the adherend. Therefore, the primary objective of a surface pretreatment is to increase the surface energy of the adherend as much as possible. The influence of surface pretreatment and aging conditions on the short- and long-term strength of adhesive bonds should be taken into account for durability design. Some form of substrate pretreatment is always necessary to achieve a satisfactory level of long-term bond strength. In order to improve the performance of adhesive bonds, the adherends surfaces (i.e., metallic or non-metallic) are generally pretretead using the (a) physical, (b) mechanical, (c) chemical, (d) photochemical, (e) thermal, or (e) plasma method. Almost all pretreatment methods do bring some degree of change in surface roughness but mechanical surface pretreatment such as grit-blasting is usually considered as one of the most effective methods to control the desired level of surface roughness and joint strength. Moreover, the overall effect of mechanical surface treatment is not limited to the removal of contamination or to an increase in surface area. This also relates to changes in the surface chemistry of adherends and to inherent drawbacks of surface roughness, such as void formations and reduced wetting. Suitable surface pretreatment increases the bond strength by altering the substrate surface in a number of ways including (a) increasing surface tension by producing a surface free from contaminants (i.e., surface contamination may cause insufficient wetting by the adhesive in the liquid state for the creating of a durable bond) or removal of the weak cohesion layer or of the pollution present at the surface, (b) increasing surface roughness on changing surface chemistry and producing of a macro/microscopically rough surface, (c) production of a fresh stable oxide layer, and (d) introducing suitable chemical composition of the oxide, and (e) introduction of new or an increased number of chemical functions. All these parameters can contribute to an improvement of the wettability and/or of the adhesive properties of the surface.

This study concerns the surface and adhesive properties of isotactic polypropylene (iPP) modified by an electric discharge plasma and affected by long-term hydrophobic recovery of the polymer surface after modification. The investigations were focused on the change in polarity of the modified polymer expressed by the polar fraction as well as on the decrease in the surface free energy, its polar component and mechanical work of adhesion (A _m) to polyvinyl acetate. A _m of modified iPP to polyvinyl acetate as a function of polar fraction can be described by a mathematical formula. It has been confirmed that the most intensive decrease in the surface and adhesive properties investigated is produced by the long-term hydrophobic recovery of the polymer appears in the course of the first 30 days after its modification. During subsequent aging the process of polymer hydrophobic recovery proceeds more slowly. It has been found that the value of surface and adhesive properties of iPP as well as the dynamics of the decrease in these properties during hydrophobic recovery of the surface after modification is, in the main, dependent on the iPP crystallinity.

A study of the durability of corona discharge plasma effects on a polymer surface was investigated in this work. We used the corona discharge plasma technique to modify the wettability properties of low density polyethylene (LDPE) film and evaluated the influence of relative humidity and temperature on the aging process with three different storage conditions. The effects of the aging process on the plasma-treated surface of LDPE film were quantified by contact angle measurements, Fourier-transformed infrared spectroscopy, and X-ray photoelectron spectroscopy. The results obtained with these techniques have allowed us to determine how the aging process promotes changes in the plasma-treated surface by decreasing its wettability and taking place a remarkable hydrophobic recovery process.

Hydrophilicity of polyethylene modified by electric discharge in the course of aging was investigated. The experiments were carried out with the foils of low-density polyethylene (PE) containing additives as well as with additive-free foils. Antiblocking or sliding agents, antioxidants and antistatic agents were used as additives. The results showed that the absence of additives in PE was responsible for the higher degree of modification of PE foils by corona discharge when compared with the polymer containing additives. The value of surface free energy (SFE) found after 30 days of aging of the modified PE foils was lower than the value recommended for inking the printing foils.

The change in adhesive properties of discharge plasma-modified biaxially oriented polypropylene was not very strong. Very low changes were detected in free surface energy (FSE) values; more intensive was the decrease in the polar contribution to FSE, polar fraction and the mechanical work of adhesion to polyvinyl acetate. After 30 days of aging of the biaxially oriented polypropylene foils, the measured value of FSE was suitable for printing. It has been determined that the correlation between mechanical adhesion work to polyvinyl acetate and polar fraction of polypropylene modified by discharge plasma is linear.

Ultrahigh molecular weight polyethylene fibres have been treated in nitrogen plasma at atmospheric pressure. The plasma was generated by a pulsed electric discharge on the fibre surface. Fibre/rubber matrix interfacial adhesion was improved substantially by the plasma treatment. Zeta-potential measurements indicate an increase in hydrophilicity and basic groups density on the treated fibre surface. EPR spectrometry study reveals creation of peroxy type radicals by the plasma treatment.

Polypropylene electrets 20-μm thick obtained in a corona discharge were studied. After the electrets were charged, they were put into a vacuum chamber at various pressures and the electret surface potential was measured over a 1-h period. A desorption from the electrets is suggested to explain the results obtained.

The same underlying mathematical structure characterizes some of the most popular multicomponent models for the prediction of surface free energies and adhesion works. After a brief illustration of the general methods for the computation of liquid and solid components in typical multicomponent theories, it is shown that both model definition and component estimate may take great advantage from application of Principal Component Analysis techniques, owing to the very peculiar structure of adhesion work equations. It is also put into evidence that a problem of scale multiplicity arises as a consequence of the symmetries involved in the model equations for adhesion work and surface free energy. A special discussion is devoted to the specific cases of van Oss–Chaudhury–Good acid–base theory, Qin–Chang model and extended Drago theory, which constitute the most common multicomponent models usually applied in the analysis of adhesion phenomena.

Oxygen plasma treatment was used to change the hydrophobic polysulfone ultrafiltration membrane to the hydrophilic membrane. The contact angle of water decreased with increasing the oxygen plasma treated time of polysulfone membrane and was saturated with 20 s of oxygen plasma treated time. Functional groups introduced by oxygen plasma treatment were examined using X-ray photoelectron spectroscopy (XPS) and zeta potential of oxygen plasma treated polysulfone membrane was measured using electrophoretic light scattering (ELS) spectrometer. O/C ratio increased from 33 to 50% and isoelectric point (IEP) of membrane surface increased from pH 3 to 4.5. For oxygen plasma treated polysulfone membrane, the flow rates of pure water and gelatin solution increased at all pH range and plasma treated membranes showed less fouling at membrane surface. The mechanisms of reduced fouling and improved cleaning efficiency of oxygen plasma treated polysulfone membrane were also studied.

Nitrogen-based plasma systems such as N₂, NH₃, Ar/NH₃, and O₂/NH₃ were used to modify microporous polyethersulfone membranes. Treatments were designed to alter the surface chemistry of the membranes to create permanently hydrophilic surfaces. Contact angle measurements taken initially, as well as 1 year post-treatment confirmed that treatments using O₂/NH₃ plasmas (with a 5:3 gas flow ratio) were successful in achieving our designed goals. Analyses by FT-IR and XPS established the incorporation of NH_x and OH species in the PES membranes. Moreover, the plasma penetrates the thickness of the membrane, thereby modifying the entire membrane cross-section. Optical emission spectroscopy studies of excited state species present in the modifying gases revealed the presence of OH^*, which was not present in a 100% ammonia plasma, suggesting OH^* must play a critical role in the membrane modification process. Investigations using bubble point analysis, differential scanning calorimetry, and scanning electron microscopy demonstrate there is no damage occurring under these specific treatment conditions. The usefulness of this treatment is revealed by increased water flux, reduced protein fouling, and greater flux recovery after gentle cleaning when compared to an untreated membrane.

A plasma treatment that renders asymmetric polysulfone membranes permanently hydrophilic is reported. Our modification strategy entails treating these membranes downstream from an inductively coupled rf plasma source. Contact angle measurements confirm that the membranes are completely wettable with water as a result of H₂O plasma treatment. More importantly, the hydrophilic modification is permanent as plasma-treated membranes remain wettable for more than 16 months after plasma treatment. This treatment achieves the desired change in wettability for microporous as well as ultrafiltration polysulfone membranes, illustrating the universality of this method. XPS analysis of treated membranes demonstrates this dramatic change in wettability is a result of chemical changes in the membrane induced by plasma treatment. Moreover, the membrane modification is complete as the plasma penetrates the thickness of the membrane, thereby modifying the entire membrane cross-section.

The gas-phase reactions of ozone with CH bonds in methane, ethane, propane (secondary CH bond), and isobutane (tertiary CH bond) have been studied by semiempirical AM1 method. Reactions proceed through biradical transition state and lead to alkyl and hydrotrioxyl HOOO radicals. The latter immediately decomposes into molecular oxygen and hydroxyl radical HO. The formation of hydrotrioxides ROOOH in gas-phase reactions between ozone and hydrocarbons is shown to be highly improbable.

Describes a method of measuring the critical surface tension of film forming polymers and the effect of temperature on the surface tension. The method gave reliable results for polyethylene, polystyrene, and polymethyl methacrylate. Changes in polymer properties due to aging can be monitored by the method, and the effect of glass transition temperatures and the effect of plasticizers in a styrene/acrylic copolymer were also studied.

The effect of Ar, Ar/C2H5OH, O2 and Ar/O2 RF (13.56 MHz) plasma treatments on surface free energy and morphology, optical properties and adhesion of polycarbonate (PC) substrates has been studied. Changes in the surface properties were followed as a function of the plasma treatment time. The polar and dispersion components of the polymer free surface energy were determined on the basis of the theory of Owens, Wendt, Kaelble and Uy. It was found that all RF plasma treatments led to an increase in the polar component of PC, mainly due to an increased hydrogen bonding ability. The increase in surface free energy reached its maximum at short plasma treatment with 3:1 gas mixture of Ar/O2. This treatment also led to pronounced improvement of the adhesion of thin SiO2 films plasma deposited on modified PC substrates, while the treatments with pure oxygen or Ar/ethanol plasma had negative effect on the adhesion.

The concept that the solubility parameter is a vector composed of hydrogen bonding, polar, and dispersion components is proposed and applied with success to prediction of the solubility of 33 polymers and resins in 90 solvents and 10 plasticizers. Solvents and plasticizers can be located as points in a three dimensional system, and regions of solubility are found for polymers and resins when solubility data are plotted. Non-interacting solvents which in a mixture become interacting have been found with better than 95% accuracy in over 400 cases.

The solubility parameters of a broad spectrum of solvents and chemicals are calculated from vapor pressure data using an expression derived from the relationship of Haggenmacher. In the case of high boiling liquids, the available vapor pressure data are found to be unreliable when extrapolated to room temperature and an alternate method of calculation is proposed. A structure correlation is made using the method of Small and new values of the molar cohesion constants are developed. The problem of associations of certain molecular species is discussed and the concept of chameleonic character introduced as a qualitative explanation.

The concept that the solubility parameter is a vector composed of hydrogen bonding, polar, and dispersion components is proposed and applied with success to prediction of the solubility of 33 poylmers and resins in 90 solvents and 10 plasticizers. The application of the solubility parameter concept is described. The three dimensional solubility parameter system based on the homomorph concept has been developed on the basis of polymer solubility. The same system has been applied to the characterization of dyes, nonionic emulsifiers, and pigments. The system is also useful for selecting solvents when protective coatings are formulated with more than one polymeric solute.