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2095. Desai, S.M., and R.P. Singh, “Surface modification of polyethylene,” in Long Term Properties of Polyolefins, C. Holm and K. Kremer, eds., 231-294, Springer, 2004.

Polyolefins such as polyethylene, polypropylene and their copolymers have excellent bulk physical/chemical properties, are inexpensive and easy to process. Yet they have not gained considerable importance as speciality materials due to their inert surface. Polyethylene in particular holds a unique status due to its excellent manufacturer- and user-friendly properties. Thus, special surface properties, which polyethylene does not possess, such as printability, hydrophilicity, roughness, lubricity, selective permeability and adhesion of micro-organisms, underscore the need for tailoring the surface of this valuable commodity polymer. The present article reviews some of the existing and emerging techniques of surface modification and characterisation of polyethylene. Surface modification of polymers, polyethylene in particular, has been extensively studied for decades using conventional tools. Although some of these techniques are still in use, they suffer from distinct shortcomings. During the last two decades, different means of surface modification have been thoroughly explored. The increasing expectancy for smart materials in daily life has, of late, sharply influenced research in the area of surface modification. Technologies that involve surface engineering to convert inexpensive materials into valuable finished goods have become even more important in the present scenario. In this review article we have attempted to broadly address almost all conventional and modern techniques for the surface modification of different physical forms and chemical compositions of polyethylene. This article will hopefully stimulate further research in this area and result in the development of polyolefins with multi-functional and responsive surfaces, which would ultimately lead to the commodities of polyolefins with smart surfaces.

2064. Mesic, B., “Ways to improve the printability in flexography of PE-coated cartonboard, using 'smart' polymers and corona treatment (licentiate dissertation),” Karlstad Univ., 2004.

2014. Moghaddam, H.A., and A. Mirhabibi, “A developed method for studying the surface energy variation on high density polyethylene,” Iranian Polymer J., 13, 485-494, (2004).

In the gas flame treatment of low surface free energy (SE) substrates, such as high-density polyethylene (HDPE), problems might arise from under or over flaming, oxygen concentration differences in and around of the flame, etc. Consequently, in printing applications, the possible variation of induced SE existing on the surface, could cause distortion on printed letters. In this research, a new method based on the wetting and spreading phenomena was developed to display and study details of the SE variation on HDPE flame treated substrates. It was an easy and quick method. Results showed good agreements with previous works done on the flame treatment characteristics. The optimal flaming was achieved, while the substrate surface had been positioned about 10 to 12 mm below the tip of the flame's blue part. Also when the flaming speed had been controlled about 80 mm/s. Results from the adhesion strength test supported the optimum situations found previously by others. It was hoped that this new method could also be capable of estimating the critical SE of solid surfaces in future works.

1736. Kumagai, H., H. Denbo, N. Fujii, and T. Kobayashi, “Poly(ethylene terephthalate) decomposition process in oxygen plasma: Emission spectroscopic and surface analysis for oxygen-plasma reaction,” J. Vacuum Science and Technology, A22, 1-7, (2004).

Emission spectroscopy was applied to observe the reaction process of poly (ethylene terephthalate) (PET) in an oxygen (O2) plasma generated by a microwave discharge. As the PET was exposed in the O2 plasma flow, light emitted from the PET surface was monitored. In the diagnosis measurement, several emission peaks assigned to the Hα atomic line at 652 nm, Hβ at 486 nm, OH (2Σ→2Π) transition near 244–343 nm and CO (b3 Σ→a3 Σ) near 283–370 nm were observed and measured at various discharge times. These results indicated that after the plasma etching, the PET sample was decomposed by the oxygen plasma reaction, and then, hydrogen abstraction and carbon oxidation processes. We also observed the time profile of oxygen atom, as the atom-emission intensity at 777 nm was monitored. As Hβ atomic and OH molecule lines appeared in the presence of PET, the O atom intensity was significantly reduced. In the surface analysis on Fourier transform infrared and x-ray photoelectron spectroscopy measurements, it was found that for the PET surface treated by O2 plasma containing excited atomic oxygen species, ester bands were broken and carbonization formed on the PET surface.

1696. Al-Turaif, H., D.W. Bousfield, and P. LePoutre, “The influence of substrate absorbency on coating surface energy,” Progress in Organic Coatings, 49, 62-68, (2004).

The surface energy of coating layers influences their final properties such as their ability to repel or absorb fluids. Recent work has shown that the substrate, due to absorption, can alter the surface chemistry of the top coating layer. However, the influence of substrate properties on coating surface energies is not reported in the literature.Three coatings, based on a pigment and a latex binder, are applied on three different substrates that differ in terms of absorption properties. The three coatings were also modified with a soluble polymer. Contact angle measurements of three different probe fluids were measured. These contact angles were used to estimate the polar, dispersive, and total surface energy of the coating layers. Surface energies were also determined for the latex and pigments.The contact angles and surface energies of the latex films and pigments agree with the expected results. Most of the results for the coating layers agree with the reported surface chemistry of these coatings. Large pigment systems on absorbent substrates have a high contact angle and low surface energy. These results agree with the expected results based on the surface chemistry reported in past work. The results for the fine pigment system had low contact angles and high surface energies and did not agree with the expected results. The contact angles may be influenced by the surface roughness of the coatings or the expected surface energy of a heterogeneous surface may not be a simple function of the surface composition.

1587. Kang, J.-Y., and M. Sarmadi, “Textile plasma treatment review - synthetic polymer-based textiles,” AATCC Review, 11, 29-33, (2004).

Surface modification of textile fibers using gas plasma is a useful tool in altering the wettability, adhesiveness, and dyeability of synthetic polymer-based textiles. Plasma treatment is also effective for biomedical applications such as sterilization. Antibacterial properties can be achieved by subsequent grafting.

1586. Kang, J.-Y., and M. Sarmadi, “Textile plasma treatment review - natural polymer-based textiles,” AATCC Review, 10, 28-32, (2004).

Plasma treatment effectively alters the surface of textiles and reduces the need for using environmentally hazardous chemicals. Applications of the technology include enhancing wettability, adhesiveness of polymer surface, and anti-felting properties of wool fibers, as well as improving dyeing properties, and sterilization. Free radicals generated on the surface can induce further crosslinking or polymerization.

1488. Mullins, B.J., I. Agranovski, R.D. Braddock, and C.M. Ho, “Effect of fiber orientation on fiber wetting process,” J. Colloid and Interface Science, 269, 449-458, (2004).

The current work incorporates a microscopic study of the effect of fiber orientation on the fiber wetting process and flow of liquid droplets along filter fibers when subjected to airflow and gravity forces. Glass filter fibers in various combinations were oriented at various angles within a plane defined by the airflow direction and were supplied with distilled water in aerosol form. The behavior and flow of the liquid collected by the fibers were observed and measured using a specially developed microscope cell, detailed in the paper. The experimental results were compared to a theoretical model developed to describe the behavior. The theory and experimental results showed good agreement. The developed theory allows an optimum angle to be determined for the internal filter fiber structure in the design of wet filters. A sensitivity analysis of the model was conducted to determine the most important parameters. This will aid design of wet filtration systems such that maximal self-cleaning can be accomplished with minimal water use.

1429. Dasilva, W., A. Entenberg, B. Kahn, T. Debies, and G.A. Takacs, “Adhesion of copper to poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) surfaces modified by vacuum UV photo-oxidation downstream from Ar microwave plasma,” J. Adhesion Science and Technology, 18, 1465-1481, (2004).

Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) surfaces were exposed to vacuum UV (VUV) photo-oxidation downstream from Ar microwave plasma. The modified surfaces showed the following: (1) an improvement in wettability as observed by water contact angle measurements; (2) surface roughening; (3) defluorination of the surface; and (4) incorporation of oxygen as CF—O—CF2, CF2—O—CF2 and CF—O—CF3 moieties. With long treatment times, a cohesive failure of copper sputter-coated onto the modified surface occurred within the modified FEP and not at the Cu–FEP interface.

1261. Yun, Y.I., K.S. Kim, S.-J. Uhm, B.B. Khatua, K. Cho, J.K. Kim, and C.E. Park, “Aging behavior of oxygen plasma-treated polypropylene with different crystallinities,” J. Adhesion Science and Technology, 18, 1279-1291, (2004).

Oxygen plasma-treated quenched and annealed polypropylene (PP) films with different crystallinities were investigated to characterize the surface rearrangement behavior during aging using contact-angle measurements and X-ray photoelectron spectroscopy. Optimum plasma conditions were examined by varying the power, time and pressure. Less crystalline quenched PP showed a larger increase in water contact angle and a larger decrease of oxygen atomic concentration during aging than the more crystalline annealed PP, since the oxygen species, such as hydroxyl groups, introduced by oxygen plasma treatment, oriented towards or diffused faster into the bulk with lower crystallinity. The degree of crosslinking on the surface was enhanced after plasma treatment and, in addition to increased crystallinity, the crosslinked structure induced by plasma treatment restricted chain mobility and lowered the aging rate of the PP surface.

1251. Shen, W., B. Hutton, and F. Liu, “A new understanding on the mechanism of fountain solution in the prevention of ink transfer to the non-image area in conventional offset lithography,” J. Adhesion Science and Technology, 18, 1861-1887, (2004).

In conventional offset lithographic printing, it has been well established that the existence of a continuous layer of fountain solution (FS) on the surface of the non-image area is an essential condition to ensure correct operation of lithography. However, the mechanistic function of FS in preventing the ink from being transferred onto the non-image area has not been fully understood. Several major mechanistic interpretations can be found in the literature, which are based either on comparing of static works of adhesion and cohesion of ink and FS, or on the splitting of the 'weaker' FS layer. Although the latter becomes more accepted, direct experimental evidence is difficult to find in the literature. On the other hand, confusing information found in the literature showed that the ink-transfer (or non-transfer) observations reported in many case studies correlate well with simple comparisons of works of adhesion, cohesion and spreading data of ink/FS, ink/plate and FS/plate obtained under the static condition. These results, therefore, imply that, in explaining the function of FS in preventing ink transfer to the non-image area, the ink/FS interfacial adhesion failure would be the dominant mechanism. The work presented in this study covered two specific areas in order to address and better understand the responses of ink and FS layers and their interface to forces encountered during ink transfer. Firstly, an analysis of lithographic plates contaminated with a cationic polymer revealed that the violation of the ink non-transfer condition of the plate non-image area due to contamination could be predicted by traditional criteria of plate wetting and works of adhesion and cohesion. However, these traditional criteria cannot reliably predict the non-transfer condition of the ink on the clean non-image area that was covered by FS. Secondly, in some novel experiments conducted in this study using ice or Teflon as a substrate, the works of adhesion and cohesion were not able to predict ink transfer in most cases. Direct experimental evidence from this work revealed that splitting of the FS layer was involved in the prevention of ink transfer to the non-image areas, and that the thickness of the FS layer was critical in allowing the splitting to occur.

1217. Inagaki, N., K. Narushima, and A. Yokoi, “Surface modification of PET films by a combination of vinylphthalimide deposition and Ar plasma irradiation,” J. Adhesion Science and Technology, 18, 1517-1528, (2004).

A new surface modification technique for PET films is proposed. This technique, called VPI modification technique, is a combination of two processes: The first step involves the deposition of vinylphthalimide (VPI) on the PET film surfaces, followed by Ar plasma irradiation of the VPI-covered film surfaces. The VPI modification technique led to large increases in the N/C atom ratio on the PET film surfaces. On the VPI-modified PET film surface, a new Nls peak containing two components due to amide groups as well as imide groups appeared. The Cls signal for the VPI-modified PET film surface also showed a new component due to ketone groups. These changes indicate that VPI reacted with the PET film surfaces to form nitrogen-containing groups. VPI modification made PET film surfaces hydrophilic. The VPI-modified film surfaces showed a decrease in water contact angle from 73 degrees to 48–56 degrees.

1197. Canal, C., R. Molina, E. Bertran, and P. Erra, “Wettability, ageing and recovery process of plasma-treated polyamide 6,” J. Adhesion Science and Technology, 18, 1077-1089, (2004).

The wetting properties of polyamide 6 rods treated with radiofrequency (RF) low-temperature plasma (LTP) using three different non-polymerizing gases (air, nitrogen and water vapour) were determined using the Wilhelmy contact-angle technique. Information on the acidic or basic nature of the ionizable groups generated on the rod surface was obtained using contact-angle titration. The wettability obtained depends on the plasma gas used, and it tends to decrease with time elapsed after the treatment when the samples are kept in an air environment. However, the wettability can be recovered by immersion of the aged samples in water. The degree of recovery depends on the plasma gas used and the highest recovery was obtained with water vapour plasma treated samples. Both ageing and recovery behaviour can be attributed to the reorganisation of hydrophilic groups which tend to reversibly migrate or orient towards the bulk phase depending on the storage conditions, although other factors can also have influence.

1064. Eriksson, J.C., and S. Ljunggren, “Thermodynamics of curved interfaces in relation to the Helfrich curvature free energy approach,” in Surface and Interfacial Tension: Measurement, Theory, and Applications, Hartland, S., ed., 547-614, Marcel Dekker, 2004.

In 1878, Gibbs [1] published his celebrated “Theory of Capillarity,” the standard reference of surface thermodynamics ever since. In a rather compact-yet exhaustive and profound-manner, Gibbs treated fluid-fluid, as well as solid-fluid, interfaces and their equilibrium properties while representing the interfacial region in an Euclidean manner by a single dividing interface, preferably the so-called surface of tension. For this particular dividing surface, the standard Laplace (or Young-Laplace) equation [2]: ∆P=2Hγ (1) holds exactly for a majority of cases. Here H=(c1+c2)/2 denotes the mean curvature, γ is the interfacial tension, and ∆P is the pressure jump at the interface, and c1 and c2 are the principal curvatures of the surface of tension. Moreover, for any given interface, the interfacial tension γ attains a minimum value when the surface of tension is chosen to be the dividing surface, as may readily be verified.

1063. Song, B., A. Bismarck, and J. Springer, “Contact angle measurements on fibers and fiber assemblies, bundles, fabrics, and textiles,” in Surface and Interfacial Tension: Measurement, Theory, and Applications, Hartland, S., ed., 425-482, Marcel Dekker, 2004.

1062. Katoh, K., “Contact angle and surface tension measurement,” in Surface and Interfacial Tension: Measurement, Theory, and Applications, Hartland, S., ed., 375-424, Marcel Dekker, 2004.

The wetting phenomenon is an important issue in various technological processes. In some fields, liquids are desired to spread over solid surfaces, e.g., lubrication oils on metallic surfaces or paint on paper. On the other hand, it is necessary for hydrophobic coatings to repel water such as Teflon film on frying pans. The behavior of bubbles on solid surfaces immersed in liquid often has important effects on the performance of industrial apparatus dealing boiling or condensation. In these problems regarding wetting, it is known that the behavior of a drop or bubble on a solid surface is dependent on the three interfacial tensions between solid, gas, and liquid phases, as shown in Fig. 1. The tangential force balance between these interfacial tensions on the three-phase contact line leads to the following well-known Young’s equation [1]: σSV−σSL=σLV cos αY. (1) σSV, σSL, and σLV indicate solid-vapor, solid-liquid, and liquid-vapor interfacial tensions, respectively. The environmental atmosphere is assumed to be filled with saturated vapor of liquid. When a drop is exposed to air, however, σLV usually does not change because a thin layer of saturated vapor may be formed around the drop [2]. In the right-hand side of Eq. (1), αY is the angle between the solid surface and the liquid-vapor interface measured from the inside of the liquid phase and is called the contact angle. When the difference between the two interfacial tensions on the left-hand side of Eq. (1) is large enough to make αY on the right-hand side small, the solid is favorably wetted by the liquid. As the drop size becomes sufficiently small and the curvature of the solid-gas-liquid contact line becomes quite large, we should add a term representing the effect of line tension to the above equation [3].

1061. Blokhuis, E.M., “Liquid drops at surfaces,” in Surface and Interfacial Tension: Measurement, Theory, and Applications, Hartland, S., ed., 149-194, Marcel Dekker, 2004.

Any review on the shape of a liquid droplet on top of a solid surface has to start with the pioneering work by P.S.Laplace and Sir Thomas Young almost two centuries ago [1, 2]. Young and Laplace set out to describe the phenomenon of “capillary action” in which the liquid inside a small capillary tube may rise several centimeters above the liquid outside the tube [3]. To understand this effect, two fundamental equations were derived by Young and Laplace. The first equation, known as the Laplace or Young-Laplace equation [1], relates the curvature at a certain point of the liquid surface to the pressure difference between both sides of the surface, and we consider it next in more detail. The second equation is Young’s equation [2], which relates the contact angle to the surface tensions involved.

1060. Hartland, S., ed., Surface and Interfacial Tension: Measurement, Theory, and Applications, Marcel Dekker, 2004.

831. Hwang, Y.J., S. Matthews, M. McCord, and M. Bourham, “Surface modification of organic polymer films treated in atmospheric plasmas,” J. Electrochemical Society, 151, C495-C501, (2004).

The effect of plasma treatment on surface characteristics of polyethylene terephthalate films was investigated using helium and oxygenated-helium atmospheric plasmas. Sample exposure to plasma was conducted in a closed ventilation test cell inside the main plasma chamber with variable exposure times. The percent weigh loss of the samples showed an initial increase followed by decrease with extended exposure time, indicating a combined mechanism of etching and redeposition. The wettability as measured by the contact angle showed a sharp initial increase followed by a steady-state trend with increased exposure time, suggesting a change in surface functionality. Atomic force microscopy analysis revealed increase in surface roughness, as well as evidence of redeposition of etched volatiles. Functionality changes were measured using X-ray photoelectron spectroscopy and these changes were correlated to the new plasma-induced properties. © 2004 The Electrochemical Society. All rights reserved.

2497. Aouinti, M., P. Bertrand, and F. Poncin-Epaillard, “Characterization of polypropylene surface treated in a CO2 plasma,” Plasmas and Polymers, 8, 225-236, (Dec 2003).

The polypropylene modification in CO2 plasma mainly contributes to degradation, functionalization, and cross-linking. The degradation, whose rate is depending on CO2 dissociation and oxygen atom formation, is a quite slow reaction and it is associated with surface topography alteration, especially of the amorphous phase of the polypropylene. The surface roughness increases with the treatment duration and the amorphous phase is more degraded than the crystallized part. The functionalization, corresponding to an increase of the surface energy (57.3 mJċ m − 2 in 30 s), and to an oxidation (23 oxygen at.%) with the appearance of alcohol, ketone, and acid functions is a much faster phenomenon. Cross-linking takes also place during this type of treatment and will reinforce the stability of the modified surface.

1847. Cho, J.S., S. Han, K.H. Kim, Y.W. Beag, and S.K. Koh, “Surface modification of polymers by ion-assisted reaction,” Thin Solid Films, 445, 332-341, (Dec 2003).

Wettable surface of polymers (advanced wetting angle ∼10° and surface energy ∼ 60 ∼ 70 erg/cm2) have been accomplished by the ion assisted reaction, in which energetic ions are irradiated on polymer with blowing oxygen gas. The energies of ions are varied from 0.5 to 1.5 keV, doses 1014 to 1017 ions/cm2, and blowing rate of oxygen 0 ∼ 8 ml/min. The wetting angles are increased when the wettable polymers were exposed in air, but are remained in pure water. Improvement of surface energy is mainly due to the polar force. Surface analysis shows hydrophilic functional groups such as CDouble BondO, (CDouble BondO)Single BondO, CSingle BondO, etc., are formed without surface damage after the ion assisted reaction treatment. Comparisons between the conventional surface treatments and the ion assisted reaction are described in term of physical bombardment, surface damage, functional group, and chain mobility in polymer.

1284. Zheng, Z., et al, “A study of the influence of controlled corona treatment on UHMWPE fibres in reinforced vinylester composites,” Polymer Intl., 52, 1833-1838, (Dec 2003).

In order to illuminate the mechanisms of corona discharge treatment on ultra-high molecular weight polyethylene (UHMWPE) fibre, the effects of corona treatment power and time are discussed in detail. The surface-roughness and tensile-failure characteristics of the polyethylene fibre were determined by a scanning electron microscope (SEM). The photos from the SEM showed that the size and number of the micro-pits on the fibre surface increase with increase of corona power. The oxygen-containing groups on the fibre surface could be detected by Fourier-transform infrared attenuated total reflectance and also increased gradually with increase of corona power. The T-peel strength of composites increased from the corona treatment, and then showed a maximum value at a corona treatment time about 0.1 s with increase of treatment time. However, the tensile strength of the fibre was reduced with increase of corona power and the failure mechanism obviously changed after the treatment. The ballistic impact energy absorption of UHMWPE fibre/vinylester composite was obtained after fragment simulating projectiles (FSP) impact tests. After 6-kW corona treatment for 0.075 s, the impact energy absorbed by the laminate reached a maximum value. Copyright © 2003 Society of Chemical Industry

1051. Theodorou, D.N., “Polymers at surfaces and interfaces,” in Computer Simulations of Surfaces and Interfaces, Dunweg, B., D.P. Landau, and A.I. Milchev, eds., 329-422, Kluwer Academic, Dec 2003.

These lecture notes discuss some theoretical approaches for the prediction of the structure, thermodynamics, and dynamics of polymers at interfaces, with emphasis on self-consistent field (SCF) methods. We begin with simple models for the conformational statistics of unperturbed chains and derive the Edwards diffusion equation for a Gaussian thread in a field. We then describe a simple lattice-based approach for a polymer melt at a flat interface and results from its application. Next, we discuss mixing energetics in the lattice model and outline an extension of the lattice-based SCF theory to treat copolymers at interfaces. Correspondences are pointed out between lattice-based and continuous SCF approaches, the latter making use of the Edwards diffusion equation. As an example of continuous formulations we present Helfand and Tagami’s elegant analytical solution for a flat interface between two immiscible polymers in the limit of very large molecular weights. Following Fredrickson et al., we outline a general fieldtheoretic approach for the mesoscopic modelling of inhomogeneous polymer systems. Using a symmetric diblock copolymer as an example, we show how a saddle point approximation reduces this formalism to a SCF theory and discuss the phase diagram obtained through continuous SCF by Matsen and Schick. As an example of scaling considerations, we derive expressions for the chain length dependence of the long period of the lamellar phase of the diblock copolymer. The latter part of the notes focusses on applications and comparisons with experiment. We discuss the structure of polymer/polymer and solid/polymer interfaces in the presence of diblock copolymers. We then briefly review a hierarchical theoretical/simulation approach for exploring adhesion at a solid/polymer interface strengthened by chains terminally grafted to the solid.

1050. Telo da Gama, M.M., “Theory of wetting and surface critical phenomena,” in Computer Simulations of Surfaces and Interfaces, Dunweg, B., D.P. Landau, and A.I. Milchev, eds., 239-260, Kluwer Academic, Dec 2003.

Surfaces and interfaces exhibit a rich variety of phase transitions. While some of these phase transitions also occur in the bulk, others involve coupling between surface and bulk degrees of freedom; consequently the surface phase diagram may be rather complex even for simple Ising like systems. In these lectures I will introduce the generic 4-dimensional surface phase diagram (bulk and surface couplings, bulk and surface fields) of Ising like systems and discuss bulk vs. surface criticality. I will start with a review of surface thermodynamics and scaling of interfaces with emphasis on wetting phenomena. Then Landau mean-field theory is used to calculate the global surface phase diagram. The effects of thermal fluctuations are discussed using the capillary wave Hamiltonian: The correlation functions are calculated using Ornstein-Zernike theory for systems with short and long-range forces. Finally, I will comment on the status of the renormalization group results for 3-dimensional short-range critical wetting that are at odds with the results of simulations of the Ising model and of a recent experiment.

1049. Bishop, C.A., “Corona-treated RPVC,” AIMCAL News, 26, (Dec 2003).

2196. Hine, C., “Corona collaboration,” Paper Film & Foil Converter, 77, (Nov 2003).

2024. Dutschk, V., K.G. Sabbatovskiy, M. Stolz, K. Grundke, and V.M. Rudoy, “Unusual wetting dynamics of aqueous surfactant solutions on polymer surfaces,” J. Colloid and Interface Science, 267, 456-462, (Nov 2003).

Static and dynamic contact angles of aqueous solutions of three surfactants--anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethylammonium bromide (DTAB), and nonionic pentaethylene glycol monododecyl ether (C(12)E(5))-were measured in the pre- and micellar concentration ranges on polymer surfaces of different surface free energy. The influence of the degree of substrate hydrophobicity, concentration of the solution, and ionic/nonionic character of surfactant on the drop spreading was investigated. Evaporation losses due to relatively low humidity during measurements were taken into account as well. It was shown that, in contrast to the highly hydrophobic surfaces, contact angles for ionic surfactant solutions on the moderately hydrophobic surfaces strongly depend on time. As far as the nonionic surfactant is considered, it spreads well over all the hydrophobic polymer surfaces used. Moreover, the results obtained indicate that spreading (if it occurs) in the long-time regime is controlled not only by the diffusive transport of surfactant to the expanding liquid-vapor interface. Obviously, another process involving adsorption at the expanding solid-liquid interface (near the three-phase contact line), which goes more slowly than diffusion, has to be active.

1099. Barthwal, S.K., A.K. Panwar, and S. Ray, “Dynamic evolution of contact angle on solid substrates during evaporation,” in Contact Angle, Wettability and Adhesion, Vol. 3, K.L. Mittal, ed., 175-190, VSP, Nov 2003.

The interfacial forces which determine the interaction between a liquid and solid surface have been investigated under dynamic conditions of evaporation. The evaporation characteristics of probe liquids and their influence on the droplet of the liquid on a solid substrate have been investigated. The changes in mass, contact angle, solid–liquid contact radius during evaporation of droplets (3-90 mg) of water on glass, polycarbonate and PTFE substrates and droplets of methyl alcohol on polycarbonate, polypropylene, PTFE and high density polyethylene substrates have been examined. The evolution of contact angle and contact radius with the progress of evaporation has been investigated for each droplet-substrate system in order to identify the common trend. In the systems of water droplets on polycarbonate and glass, the contact radius remained constant with the progress of evaporation but such behavior was not observed in the case of methyl alcohol on polycarbonate, polypropylene, PTFE and high density polyethylene.

1098. Schrader, M.E., “Effect of adsorbed vapor on liquid-solid adhesion,” in Contact Angle, Wettability and Adhesion, Vol. 3, K.L. Mittal, ed., 67-94, VSP, Nov 2003.

An overview is presented of a series of papers published during the last decade which show that the conventional thermodynamic approach to liquid—solid adhesion requires some fundamental changes. It is pointed out that it has been a long-neglected fact that adsorption, as generally measured in adsorption isotherms, is actually surface excess, so that it can, in principle, be negative as well as positive. As a result, the free energy of adsorption, AF, can be positive as well as negative. Small amounts of water vapor adsorbing onto previously evacuated poly (tetrafluoroethylene) could, in principle, therefore be increasing the free energy of the low-energy polymer surface. It is further pointed out that from the strictly thermodynamic point of view, changing the free energy of a surface by adsorption of the vapor of a liquid does not necessarily change the contact angle. Resulting changes in contact angle can, however, theoretically occur from changes in the intermolecular force interaction term (proposed work of adhesion), such as those terms proposed by Good and Girifalco, Fowkes and others, where such changes would be speculative. In addition, it is pointed out that an accurate thermodynamic representation of liquid-solid adhesion should take into account the shape of the drop to be deposited (or drop that has been detached), as well as the resulting contact angle. An equation is presented for the free energy of adhesion of a spherical drop.

1097. Etzler, F.M., “Characterization of surface free energies and surface chemistry of solids,” in Contact Angle, Wettability and Adhesion, Vol. 3, K.L. Mittal, ed., 219-266, VSP, Nov 2003.

The surface chemistry and surface energetics of materials are important to the performance of many products and processes—sometimes in as yet unrecognized ways. This review is written for the researcher interested in exploring the nature of surfaces and their relation to processes involving spreading, wetting, liquid penetration and adhesion. Researchers concerned with many types of products including pharmaceuticals, printing and the making of composite materials should have interest in this topic. More specifically, this work is a review of the literature concerning the surface free energy of solids. Both theoretical approaches for understanding the surface free energy of solids are explored and contrasted, as are experimental methods for measuring surface free energy of solids. Experimental methods that offer insight into the chemical nature of surfaces but do not measure surface free energy are also discussed as these two subjects are intertwined.

1095. Kwok, D.Y., and A.W. Neumann, “Contact angle measurements and criteria for surface energetic interpretation,” in Contact Angle, Wettability and Adhesion, Vol. 3, Mittal, K.L., ed., 117-160, VSP, Nov 2003.

1088. de Gennes, P.-G., F. Brochard-Wyart, and D. Quere, “Wetting and long-range forces,” in Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves, 87-104, Springer-Verlag, Nov 2003.

1087. de Gennes, P.-G., F. Brochard-Wyart, and D. Quere, “Hysteresis and elasticity of triple lines,” in Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves, 69-84, Springer-Verlag, Nov 2003.

When we place a liquid drop on a clean, planar, solid surface, we can observe a contact angle θ E , which is precisely the angle contained in Young’s formula. Quite often, though, the surface is marred by defects that are

  • either chemical (stains, blotches, blemishes)

  • or physical (surface irregularities).

1086. de Gennes, P.-G., F. Brochard-Wyart, and D. Quere, “Capillarity: Deformable interfaces,” in Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves, 1-30, Springer-Verlag, Nov 2003.

Capillarity is the study of the interfaces between two immiscible liquids, or between a liquid and air. The interfaces are deformable: they are free to change their shape in order to minimize their surface energy. The field was created in the early part of the 19th century by Pierre Simon de Laplace (1749–1827) and Thomas Young (1773–1829). Henri Bouasse wrote a wonderful account of developments in capillarity in a book he published in 1924.1 This discipline enables us to understand the games water can play to break the monotony of a rainy day or the tricks it performs while washing dishes. On a more serious note, capillarity plays a major role in numerous scientific endeavors (soil science, climate, plant biology, surface physics, and more), as well as in the chemical industry (product formulation in pharmacology and domestics, the glass industry, automobile manufacturing, textile production, etc.).

2562. Villermet, A., P. Cocolius, G. Rames-Langlade, F. Coeuret, et al, “ALDYNE surface treatment by atmospheric plasma for plastic films converting industry,” Surface and Coatings Technology, 174-175, 899-901, (Oct 2003).

Based on the Corona process and a substitution of air with specific gaseous mixtures into the discharge area, the newly developed surface treatment ALDYNE™ offers both high level improvement and high flexibility to film converters. By grafting nitrogen-based chemical functions, it confers to the treated surface excellent properties such as high surface energy and high adhesion of coatings.

2512. Drnovska, L.L. Jr., V. Bursikova, J. Zemek, and A.M. Barros-Timmons, “Surface properties of polyethylene after low-temperature plasma treatment,” Colloid and Polymer Science, 281, 1025-1033, (Oct 2003).

The effect of oxygen and ammonia plasma treatments on changes of the surface properties of linear high-density polyethylene (HDPE) was studied. Surface energies of the polymer substrates were evaluated by contact angle measurements using Lifshitz-van der Waals acid-base approach. The surface energy of untreated HDPE is mainly contributed by Lifshitz-van der Waals interactions. After 5 min of plasma treatment, hydrogen bonds are formed on the surface, which is reflected in predominant acid-base interactions. The SEM results obtained demonstrate considerable changes of the surface roughness due to different types of the plasma gas used. Evolution of oxygen- or amino-containing moieties was detected by XPS and ATR FT IR. The prepared polyethylene surfaces were used as a basic support for further fabrication of novel hybrid biocomposite sandwich structures.

1234. Mekishev, G.A., T.A. Yovcheva, E. Guentcheva, and S. Nedev, “On the charge decay in PP electrets stored at pressures lower than atmospheric,” J. Materials Science: Materials in Electronics, 14, 779-780, (Oct 2003).

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.

1067. Yializis, A., “Surface functionalization of web surfaces using treatment grafting and polymer coatings,” in AIMCAL 2003 Fall Technical Conference, AIMCAL, Oct 2003.

1066. Goodwin, A., “Atmospheric pressure plasma technologies for surface modification of polymers,” in AIMCAL 2003 Fall Technical Conference, AIMCAL, Oct 2003.

2974. Deshmukh, R.R., and N.V. Bhat, “The mechanism of adhesion and printability of plasma processed PET films,” Materials Research Innovations, 22, 283-290, (Sep 2003).

Of the several techniques available for the surface modification, plasma processing has proved to be very appropriate. The low temperature plasma is a soft radiation source and it affects the material only over a few hundred Å deep, the bulk properties remaining unaffected. Plasma surface treatment also offers the advantage of greater chemical flexibility. PET films are widely used for packaging and electrical insulation. The studies of adhesion and printability properties are important. In the present study PET films are treated in air plasma for different time of treatment. The improvement in adhesion is studied by measuring T-peel and Lap shear strength. In addition, printability of plasma treated PET films is studied by cross test method. It has been found that printability increases considerably for plasma treatment of short duration. Therefore it is interesting to study the surface composition and morphology by contact angle measurement, ESCA and AFM. Surface energy and surface roughness can be directly correlated to the improvement in above-mentioned surface related properties. It has been found that the surface oxidation occurs containing polar functional groups such as CSingle BondO, COO. A correlation of all such observations from different techniques gives a comprehensive picture of the structure and surface composition of plasma treated PET films.

 

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