ACCU DYNE TEST ™ Bibliography
Provided as an information service by Diversified Enterprises.
showing result page 19 of 77, ordered by
2952. Forster, F., “Corona treatment for extrusion coating and laminating production lines,” PFFC, 28, 16-18, (Jun 2023).
1918. Fort, T., Jr., and H.T. Patterson, “A simple method for measuring solid-liquid contact angles,” J. Colloid Science, 18, 217-222, (Mar 1963).
A simple apparatus and technique are described for measuring contact angles formed by liquid drops on solid surfaces. The procedure is a modification of one described 25 years ago by Langmuir and Schaeffer. It is based on observation of the angle at which light from a point source is reflected from a liquid drop surface at its contact point with a solid. The technique gives results the same, within experimental error, as those obtained by other investigators who used the usual “drop profile” method. The apparatus has the advantages of ease of construction and operation, ruggedness, and low cost coupled with high precision and accuracy.
2034. Fourches, G., “An overview of the basic aspects of polymer adhesion, I: Fundamentals,” Polymer Engineering and Science, 35, 957-967, (Jun 1995).
Adhesion between two substrates is a complex phenomenon which at present is still not well understood. The important existing adhesion models (electrical, diffusion, thermodynamic adsorption, chemical, etc.) are reviewed in order to try to explain their mechanisms. Thermodynamic adsorption is now believed to be one of the most importnat mechanisms by which adhesion is achieved. Difusion and wetting are kinetic means in attaining good adsorption of a polymer at the interface. In the case of this model (thermodynamic adsorption), the notion of surface energy is developed and the importance of this property in the understanding of adhesion phenomena is emphasized. The methods of determining the surface characteristics of low and high energy solids are presented. The role played by acid-base interactions in adhesion is also mentioned.
105. Fowkes, F.M., “Determination of interfacial tensions, contact angles, and dispersion forces by assuming additivity of intermolecular interactions at surfaces (letter),” J. Physical Chemistry, 66, 382, (1962).
106. Fowkes, F.M., “Additivity of intermolecular forces at interfaces, I. Determination of the contribution to surface and interfacial tensions of dispersion forces in various liquids,” J. Physical Chemistry, 67, 2538-2541, (1963).
107. Fowkes, F.M., “Attractive forces at interfaces,” Industrial and Engineering Chemistry, 56, 40-52, (Dec 1964).
Equations based on a simple model of surfaces and interfaces have been found useful for relating quantitatively several previously unrelated fields of surface chemistry {10-13). These equations introduce a new term — the London dispersion force contribution to the surface free energy (7d)—and make use of this term for the accurate calculations of surface tension, interfacial tension, contact angles, heats and free energies of immersion, heats and free energies of adsorption, and the long-range van der Waals attractive forces. The accuracy of predictions of values verifiable by experiment lead one to expect that predictions of un-verifiable quantities, such as the magnitude of attractive forces at solid-solid interfaces, are to be trusted. This approach should appeal especially to those who need to use the results of surface chemistry and would prefer to calculate from existing values rather than make new experimental determinations. It should also appeal to those teaching surface chemistry in that it relates for the first time several widely separated fields of surface chemistry. Most noteworthy is the ability to calculate heats and free energies of adsorption of gases on solid surfaces directly from measurements of surface tensions and contact angles. The calculation of the long range van der Waals attractive constant, A, from values of 7d is also very attractive.
108. Fowkes, F.M., “Comments on 'The calculation of cohesive and adhesive energies', by J.F. Padday and N.D. Uffindell (letter),” J. Physical Chemistry, 72, 1407, (1968).
Sir: Padday and Uffindell produced a well organized and readable article, but unfortunately their mathematics is incorrect (by nearly one order of magnitude) because intermolecular potentials were integrated over molecular distances, breaking a fundamental principle of integral calculus.
458. Fowkes, F.M., “Role of acid-base interfacial bonding in adhesion,” J. Adhesion Science and Technology, 1, 7-27, (1987).
The strength of macroscopic adhesive bonds of polymers is known to be directly proportional to the microscopic exothermic interfacial energy changes of bond formation, as measured by Dupre's 'work of adhesion'. Since the work of adhesion can be very appreciably increased by interfacial acid-base bonding with concomitant increases in adhesive bond strength, it is important to understand the acid-base character of polymers and of the surface sites of substrates or of the reinforcing fillers of polymer composites. The best known acid-base bonds are the hydrogen bonds; these are typical of acid-base bonds, with interaction energies dependent on the acidity of the hydrogen donor and on the basicity of the hydrogen acceptor. The strengths of the acidic or basic sites of polymers and of inorganic substrates can be easily determined by spectroscopic or calorimetric methods, and from this information one can start to predict the strengths of adhesive bonds. An important application of the new knowledge of interfacial acid-base bonding is the predictable enhancement of interfacial bonding accomplished by surface modification of inorganic surfaces to enhance the interfacial acid-base interactions.
1343. Fowkes, F.M., “Acid-base interactions in polymer adhesion,” in Physico-Chemical Aspects of Polymer Surfaces, Vol. 2, Mittal, K.L., ed., Plenum Press, 1983.
1596. Fowkes, F.M., “Quantitative characterization of the acid-base properties of solvents, polymers and inorganic surfaces,” J. Adhesion Science and Technology, 4, 669+, (1990) (also in Acid-Base Interactions: Relevance to Adhesion Science and Technology, K.L. Mittal and H.R. Anderson Jr., eds., p. 93-116, VSP, Nov 1991).
The growing realization of the importance of intermolecular acid-base interactions in promoting the solubility, adsorption, and adhesion of polymers to other materials has caused a demand for the quantitative characterization of the acid-base properties of the commonly used solvents, polymers, and inorganic fillers and substrates. There have been several recent advances in the measurement techniques for such determinations, especially in the fields of inverse gas chromatography, microcalorimetry, ellipsometry, FTIR, NMR, and XPS spectroscopy, all leading to the capability of determining the Drago E and C constants or the Gutmann acceptor numbers (AN) or donor numbers (DN) for the acidic or basic sites of solvents, polymers, or inorganic surfaces. In the last year, new studies have also allowed the characterization of the specific acid-base cohesive interactions in solvents and polymers, and the determination, from contact angle measurements on polymers, of the surface concentration and strength of acidic and basic surface sites. All of these techniques are discussed in this paper and it is expected that they will soon become standard laboratory practices.
1604. Fowkes, F.M., “Dispersion force contributions to surface and interfacial tensions, contact angles, and heats of immersion,” in Contact Angle, Wettability and Adhesion: The Kendall Award Symposium Honoring William A. Zisman (Advances in Chemistry Series 43), F.M. Fowkes and R.F. Gould, eds., 99-111, American Chemical Society, 1964.
In his opening remarks at the first symposium in this series Professor Robert Good pointed out that Galileo in the 17 century was quite likely the first investigator to observe contact angle behavior with his experiment of floating a thin gold leaf on top of a water surface. Since that time contact angle measurements have found wide application as a method for determining the energetics of surfaces. This, in turn, has a profound effect on the wettability and adhesion of liquids and coatings to surfaces.
1530. Fowkes, F.M., and M.A. Mostafa, “Acid-base interactions in polymer adsorption,” Industrial & Engineering Chemistry Product Research & Development, 17, 3-7, (1978).
Most polymers and inorganic materials have acidic or basic sites (or both) which can interact to enhance wettability, adsorption, charge-transfer, and adhesion. These interactions, termed “polar” in the past, are independent of dipole moments and occur only when one material has acid groups which can interact with basic groups of the other material. the presence of a third component (solvent, plasticizer, penetrant, etc.) can interfere with adsorption, charge-transfer, or adhesion if the third component has strong enough acid-base interactions with either or both components. Water, a weak acid and a weak base, tends to weaken adhesion of polymers to inorganic materials but not when these have strong acid-base interactions.
A quantitative approach to predicting the enthalpy ΔHab of acid-base interactions between polymers and inorganic surfaces is presented based on determining the E and C constants of Drago's correlation for polymers and inorganic surfaces. Preliminary E and C constants are presented for polymethylmethacrylate, for chlorinated polyvinylchloride, for silica surfaces and for iron oxide surfaces.
1480. Fowkes, F.M., and R.F. Gould, eds., Contact Angle, Wettability and Adhesion: The Kendall Award Symposium Honoring William A. Zisman (Advances in Chemistry Series 43), American Chemical Society, 1964.
103. Fowkes, F.M., and W.D. Harkins, “The state of monolayers adsorbed at the interface solid-aqueous solution,” J. American Chemical Society, 62, 3377-3386, (1940).
104. Fowkes, F.M., and W.M. Sawyer, “Contact angles and boundary energies of a low energy solid (letter),” J. Chemical Physics, 20, 1652, (1952).
FUNDAMENTAL quantities associated with the wetting of solids are the free energies of the solid/vapor boundary ('Y SV) and the solid/liquid boundary ('Y SL). These have been obtained for the special case of a glassy solid fluorocarbon on which the con tact angles (8) have been measured for liquids of widely different surface tension ('Y LV). The excellent agreement between the observed angles and those calculated from the theoretical relation,
1789. Fox, H.W., P.W. Taylor, and W.A. Zisman, “Polyorganosiloxanes: Surface active properties,” Industrial and Engineering Chemistry, 39, 1401-1409, (1947).
A STUDY has been made of the densities, the surface tensions and their temperature coefficients, the interfacial tensions against water, the spreading pressures, and the force-area and potential-area relations of monolayers on water of various types of linear polyorganosiloxanes. The McLeod constants and parachors have been calculated, and their application to the type analysis of the silicones is discussed. Relations have been found between the critical spreading pressure, the spreading coefficient, and the viscosity. A study of the force-area curves revealed that the polymethylsiloxanes and the related polymers containing a small proportion of phenyl substituents are able to coil reversibly into helices made up of about six monomers per turn. Conclusions relative to the molecular structures in thin films have been carried over to the three-dimensional liquid state.
109. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, I. Polytetrafluoroethylene,” J. Colloid Science, 5, 514-531, (1950).
1. Methods of preparing surfaces of polytetrafluoroethylene (TFE) are described which permit obtaining reproducible and reliable measurements of contact angles with liquids. Polytetrafluoroethylene is found to be an ideal low energy surface for the study of the wetting relations of a solid with a wide variety of organic and inorganic liquids.
2. It is shown that all but the lowest-boiling liquids studied do not adsorb on TFE sufficiently from the vapor to produce a significant spreading pressure. Hence the πE term in the expression for the work of adhesion (WA) is negligible and WA = γLV(1 + cos θ). The calculated values of WA are found to be consistent and reasonable.
3. It is found that for each homologous series of liquids cos θ is a linear function of γLV. The constants of the resulting relations are given. From this WA − Wc can be expressed as a function of γLV alone.
4. The observations show that there is a critical surface tension (17.5–20.5 dynes/cm.) below which liquids wet TFE.
5. It is concluded that the corrected Young-Dupré relation coupled with the spreading coefficient permits a rational description of the results. The Doss and Rao relation for the surface condensation leads to such high values for high-boiling liquids as to make it unlikely that the theory is correct.
110. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, II. Modified tetrafluoroethylene polymers,” J. Colloid Science, 7, 109-121, (1952).
1. Data are presented on the equilibrium contact angles of a wide variety of liquids on specially prepared surfaces of halogenated derivatives of polyethylene. The free energy decrease of immersion (fSL), the work of adhesion (WA), and the spreading coefficients have been calculated for the liquids which do not spread. The free energy decrease on immersion of these solids in the saturated vapor of most of the liquids of this study is shown to be negligible.
2. For each solid surface the contact angle and spreading coefficient follow the relation to liquid surface tension reported previously for polytetrafluoroethylene, i.e., as the liquid surface tension increases, the contact angle increases and the spreading coefficient decreases.
3. Substitution of chlorine or hydrogen for fluorine in these polymers increases WA, fSL, and the spreading coefficient with respect to a given liquid, the increase depending on the proportion of nonfluorine substituent. Substitution of hydrogen for fluorine has a smaller effect in this respect than substitution of chlorine for fluorine.
4. It is shown that when fSL for a given solid in a series of liquids is constant, the plots of WA υs. surface tension and spreading coefficient υs. surface tension should be straight lines with positive and negative 45° slopes, respectively. The data presented for the fluorinated polymers and the liquid n-alkanes and di-n-alkyl ethers fall on such lines. The values of fSL for the fluorinated polymers plot as a straight line against mole per cent fluorine substitution.
5. There appears to be a maximum value of WA characteristic of the polymer, which is identical with the work of adhesion given by the liquid having a contact angle of 90° on the given solid.
6. It is shown experimentally that there are many exceptions to the “rule” that nonpolar liquids wet nonpolar solids.
7. From the data it is shown that recent attempts to measure the surface tension of solids by contact angle measurements alone involve unjustifiable assumptions.
111. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, III. Hydrocarbon surfaces,” J. Colloid Science, 7, 428-442, (1952).
1. Contact angle measurements have been made of a wide variety of liquids on clean, smooth surfaces of polyethylene, paraffin, and surfaces of single crystals of n-hexatriacontane (C36). The calculated value of the final spreading coefficient (SLV∘/SV∘) is given and from the data there can be calculated the values of the free energy of immersion (fSL), and the work of adhesion (WA). The free energy of immersion of the solid in the liquid vapor can be neglected in these calculations since it is believed to be quite small for surfaces of low adsorptivity and low free surface energy. It is shown that the methyl-rich surfaces of C36 and paraffin are not wetted by a wide variety of organic liquids, including the n-alkanes, so that the rule that nonpolar solids are wetted by nonpolar liquids is again found to be erroneous.
2. Wettability is found to decrease in the order polyethylene, paraffin, C36. This is attributed to the increase in the proportion of methyl to methylene groups in the surface. The C36 surface, like all higher n-alkane crystals, is shown to be the least wettable of all hydrocarbon surfaces since its surface comprises only methyl groups arranged in the closest possible packing. It is shown that it should be possible to estimate the packing of adsorbed monolayers of straight-chain hydrocarbon derivatives by comparing the hydrophobic contact angle to the angle on C36. Many of the variations of the hydrophobic contact angle on paraffin found in the literature are shown to be attributable to variations in the methylmethylene ratio in the surface.
3. In contrast to the fluorinated polymers, paraffin and C36 are shown to have multiple curves of cos θ vs. γ. The multiplicity of these curves is attributed to differing dependencies of γSL on γLV∘ due to variation in the constitution of the liquid. Increase in adhesion of hydrocarbon surfaces to liquids is found to be in the order: liquids containing oxygen or fluorine; aliphatic hydrocarbons, aromatic hydrocarbons.
4. It is shown that variation of the free energy of immersion of the n-alkane series of liquids on a given hydrocarbon surface is the resultant of two competing tendencies: i.e., increased adhesion due to increase in methylene to methyl ratio in the liquid, and decrease in adhesion due to increase in surface tension of the liquid. For the C36 surface, the latter tendency predominates; for the paraffin surface, the former tendency predominates, fSL is shown to be the upper bound of the solid surface tension for systems where γSL ⩾ 0.
5. It is shown that in general there is more than one value of the critical surface tension (below which liquids spread on a given surface) for hydrocarbon surfaces, depending on the value of γSL given by a liquid of given surface tension. The fluorinated polymers are shown to be a special case where the surfaces are independent of the nature of the liquid and therefore have essentially a single value of γC.
112. Fox, H.W., and W.A. Zisman, “The spreading of liquids on low energy surfaces, VI. Branched-chain monolayers, aromatic surfaces, and thin liquid films,” J. Colloid Science, 8, 194-203, (1953).
A study has been made of the wettability of adsorbed monolayers of branched-chain and cyclic molecules. It is shown that such monolayers are nonwetted by organic liquids with surface tensions higher than a critical value characteristic of the monolayer. Oleophobicity is therefore not restricted to monolayers whose surfaces comprise close-packed methyl groups, the latter merely representing an extreme case. It is shown, further, that adsorbed layers of nonpolar liquids behave, as regards wettability, like low-energy solids with the same atomic groups exposed in the surface. It is concluded that the free surface energy of adsorbed liquid or solid films depends only on the atomic groups in the surface and their packing.
861. Fracassi, F., “Architecture of RF plasma reactors,” in Plasma Processing of Polymers (NATO Science Series E: Applied Sciences, Vol. 346), d'Agostino, R., P. Favia, and F. Fracassi, eds., 47-64, Kluwer Academic, Nov 1997.
In order to achieve a complete understanding and control of plasma processes an appropriate knowledge of the structure of the particular glow discharge utilized is necessary. This is extremely important because the electrical potential distribution inside a plasma reactor is not uniform and therefore, as a function of the reactor geometry and sample position, charged particles are accelerated from the plasma bulk to the substrate to be treated by different potential drops, ie they impinge on different surfaces with different energy.
459. Frederickson, G.H., “Surface ordering phenomena in block copolymer melts,” Macromolecules, 20, 2535-2542, (Oct 1987).
A mean field theory is presented to describe surface ordering phenomena in diblock copolymers near the microphase separation transition (MST). We consider a near-symmetric diblock melt in the vicinity of a solid wall or free surface, such as a film-air interface. The surface is allowed to modify the Flory interaction parameter and the chemical potential in the adjacent copolymer layer. The composition profile normal to the surface is investigated both above and below the MST. In contrast to the surface critical behavior of binary fluids or polymer blends, we find interesting oscillatory profiles in copolymers that arise from the connectivity of the blocks. These composition profiles might be amenable to study by ellipsometry, by evanascent wave-induced fluorescence, or by scattering techniques. Wetting and other surface phenomena and transitions in block copolymers are briefly discussed.
2700. French, J., P. Nugent, F. Laxamana, and A. Adarlo, “Ozone adhesion process for insulating container manufacture,” U.S. Patent 9694521, Jul 2017.
Systems and methods for improving adhesion of an insulating foam to a molded polymeric insulating structure through use of ozone gas for functionalization of molded polymeric surfaces of an internal cavity of the insulating structure.
1980. Frerichs, H., J. Stricker, D.A. Wesner, and E.W. Kreutz, “Laser-induced surface modification and metallization of polymers,” Applied Surface Science, 86, 405-410, (Feb 1995).
Laser-induced surface modification of different polymers is presented as a suitable pretreatment of surfaces in a two-step metallization process. Materials such as polyamide (PA), polypropylene (PP), polystyrene (PS), polycarbonate (PC), acrylbutadienestyrene (ABS), styreneacrylnitrile (SAN), polybutadieneterephthalate (PBT), and polyoxymethylene (POM) were treated by excimer-laser radiation at 248 nm in air. The aim of this study is to investigate different processing regimes of surface modification and ablation to increase surface roughness. Therefore, the laser-processing variables fluence F, repetition rate v and pulse number N are varied and the ablation depth, optical penetration depth, absorption coefficient and ablation threshold are determined. The metallization of pretreated (laser, wet chemical and plasma etching) polymers is investigated for different surface morphologies. The used metallization processes were electroplating and physical vapour deposition (PVD). The adhesion of the deposited films is measured with scratch and tape test methods in order to determine the regimes of suitable surface modification for metallization.
113. Freud, B.B., and H.Z. Freud, “A theory of the ring method for the determination of surface tension,” J. American Chemical Society, 52, 1772-1782, (1930).
2908. Frickley, J., “Solid, liquid, gas and plasma energy: 3DT's improved PlasmaDyne Pro,” Plastics Decorating, 18, (Apr 2022).
2513. Fridman, A., A. Chirokov, and A. Gutsol, “Non-thermal atmospheric pressure discharges,” J. Physics D: Applied Physics, 38, R1-R24, (2005).
There has been considerable interest in non-thermal atmospheric pressure discharges over the past decade due to the increased number of industrial applications. Diverse applications demand a solid physical and chemical understanding of the operational principals of such discharges. This paper focuses on the four most important and widely used varieties of non-thermal discharges: corona, dielectric barrier, gliding arc and spark discharge. The physics of these discharges is closely related to the breakdown phenomena. The main players in electrical breakdown of gases: avalanches and streamers are also discussed in this paper. Although non-thermal atmospheric pressure discharges have been intensively studied for the past century, a clear physical picture of these discharges is yet to be obtained.
114. Friedman, S., “In for a treat,” Package Printing, 45, 42-44, (Apr 1998).
115. Friedman, S., “Surface Buzz,” Package Printing, 46, 68-74, (Oct 1999).
1029. Friedrich, J., “Plasma treatment of polymers,” Adhasion Kleben & Dichten, 41, 28-33, (1997).
846. Friedrich, J., G. Kuhn, R. Mix, I. Retzko, V. Gerstung, St. Weidner, R.-D. Schul, “Plasma polymer adhesion promoters for metal-polymer systems,” in Polyimides and Other High Temperature Polymers: Synthesis, Characterization and Applications, Vol. 2, K.L. Mittal, ed., 359-388, VSP, Jun 2003.
The retention of chemical structure and functional groups during plasma polymerisation was investigated. Usually plasma polymer layers, prepared by continuous wave radio-frequency plasma, are often chemically irregular in their structures and chemical compositions. To minimise these irregularities, low wattages and the pulsed plasma technique were applied to avoid fragmentations. The polymerisation of vinyl and acryl-type monomers was strongly enhanced in the dark phase (plasma-off) of a pulsed rf plasma caused by the reactivity of the vinyl or acryl-type double bonds. Bifunctional monomers with acryl or allyl double bonds and also polar groups such as OH, NH2, and COOH were used to produce plasma polymers with defined (regular) structures and a high density of a single type of functional groups. The maximum yields were 30 OH, 18 NH2, 24 COOH groups per 100 C atoms. To vary the density of functional groups a chemical copolymerisation with “chain-extending” comonomers such as butadiene and ethylene was initiated in the pulsed plasma. The composition of these copolymers was investigated by XPS and IR spectroscopy. Homopolymers and copolymer layers were deposited on polypropylene (PP) foils and then aluminium was thermally evaporated. The peel force increased considerably and showed a dependence on the density of functional groups. The plasma polymer deposition was also monitored in situ by the Self-Exciting Electron Resonance Spectroscopy (SEERS) to show correlations between plasma parameters and properties of the deposited plasma polymer layers measured “quasi-in situ” by coupling the plasma chamber with an XPS spectrometer.
1583. Friedrich, J., I. Loeschcke, H. Frommelt, et al, “Aging and degradation of poly(ethylene-terephthalate) in an oxygen plasma,” Polymer Degradation and Stability, 31, 97-114, (1991).
The ageing of thin PET films in an oxygen plasma was investigated. After several hours exposure a large decrease in mechanical strength was observed. Plasma particle bombardment, chemical reactions and the plasma vacuum UV radiation cause extensive chemical and structural changes. The chemical reactions leading to the ageing process were identified.
1212. Friedrich, J., W. Unger, A. Lippitz, L. Wigant, and H. Wittrich, “Corona, spark and combined UV and ozone modification of polymer films WeBP23,” Surface and Coatings Technology, 98, 879-885, (Jan 1998).
Different types of plasma, irradiative and chemical activation were compared in terms of surface functionalization. Corona and spark jet plasmas are characterized by low gas temperatures and high rates in surface modification. UV irradiation in the presence of ozone does not involve any particle bombardment and acts only by enhanced photooxidative processes. Although ion implantation can be avoided, this method is not free of radiative damage in both the surface-near region and the bulk of polymers. Furthermore, its functionalization rate is low. In relation to low-pressure O2 plasma modification, all treatments mentioned here have a low efficiency in adhesion promotion due to oxidative degradation of macromolecules and formation of molecular debris known as the “weak boundary layer”.
1163. Friedrich, J., and G. Kuhn, “Contribution of chemical interactions to the adhesion between evaporated metals and functional groups of differeent types at polymer surfaces,” in Adhesion: Current Research and Applications, W. Possart, ed., 265-288, Wiley-VCH, Dec 2005.
Single-type functionalizations with different types of functional groups at polypropylene (PP) and polytetrafluoroethylene (PTFE) surfaces were achieved using, instead of a simple plasma modification, either a combined plasmachemical–chemical process or the pulsed plasma-initiated homo-or copolymerization of monomers carrying functional groups. The combined process consists of O2 plasma pretreatment and wet-chemical reduction of O functional groups to OH groups using diborane, vitride (sodium bis (2-methoxyethoxy) aluminum hydride), or LiAlH4. The high degree of retained chemical structure and functional groups during the low-power pulsed plasma polymerization was found to be a prerequisite for producing well-defined, adhesion-promoting plasma polymer layers as model surfaces with high concentrations of exclusively or predominantly one type of functional group, such as OH, NH2, or COOH. The maximum concentrations of functional groups were found to be 31 OH, 21 NH2 or 25 COOH groups/100 C atoms using allyl alcohol, allylamine, or acrylic acid, respectively, as monomers in the plasma polymerization process and 14 OH groups/100 C atoms by applying the combined O2 plasma/diborane reduction process. To vary the density of functional groups, a so-called plasma-initiated gas-phase radical copolymerization with ethylene or styrene as a “chain-extending” comonomer, or butadiene as “chemical crosslinker” was employed. The peel strength of evaporated aluminum layers on unspecifically oxygen-plasma functionalized polypropylene (PP) and polyethylene (PE) shows in each case a maximum at 20 O per 100 C atoms. Initially the peel strength increased linearly with the concentration of functional groups when PP or polytetrafluoroethylene (PTFE) substrates were coated with plasma polymers or copolymers carrying a single type of adhesion-promoting functional groups. The ranking of the adhesion-promoting effect is CH2< NH2 (OH< COOH, and corresponds to the tendency to form chemical bonds between aluminum and the different functional groups.
2575. Friedrich, J.F., The Plasma Chemistry of Polymer Surfaces: Advanced Techniques for Surface Design, Wiley-VCH, 2012.
1891. Friedrich, J.F., L. Wigant, W. Unger, et al, “Barrier properties of plasma-modified polypropylene and polyethylene terephthalate,” J. Adhesion Science and Technology, 9, 1165-1180, (1995) (also in Polymer Surface Modification: Relevance to Adhesion, K.L. Mittal, ed., p. 121-136, VSP, May 1996).
Plasma treatment changes the solvent absorption and permeation as well as the swelling properties of polymers. Enchanced solvent absorption and swelling are effects of an improved solvent compatibility. The plasma introduces a large number of different groups at the polymer surface depending on the nature of the plasma. Fluorine-containing plasmas can replace hydrogen atoms of the polymer molecule with fluorine atoms. Moreover, fluorine-containing plasma polymer layers can be formed. All these processes reduce the resulting surface free energy, reduce the diffusion length of solvent molecules, and produce a barrier layer. We have studied the formation of solvent barriers by plasma fluorination and by crosslinking by ultraviolet (UV) radiation. Thin foils of polypropylene (PP) and polyethyleneterephthalate (PET) were used as substrates. CF4, SF6, and SOF2 were applied as sources of fluorine atoms. Hexafluoropropene, tetrafluorethylene, and perfluorohexylethylene form plasma polymer layers on the polymer substrates. Test solvents were n-pentane, tetrachloroethylene, dimethylsulfoxide, and mixtures of n-pentane and methanol.Plasma treatment changes the solve The permeation rate of solvents through plasma-modified polymers was measured gravimetrically. Mass spectrometry was applied to analyze the permeating components of the solvent mixtures. Fluorination of surface layers by plasma-chemical (CF4, SF6) means considerably reduces the permeation rate of PP (95% barrier effect) and PET (100%). The preferred permeation of one component of the pentane/methanol mixture is influenced by the polarity of plasma-introduced groups at the polymer surface.
2539. Friedrich, J.F., R. Mix, and G. Kuhn, “Adhesion of metals to plasma-induced functional groups at polymer surfaces,” Surface and Coatings Technology, 200, 565-568, (Oct 2005).
The peel strength of aluminium to polypropylene and poly(tetrafluoroethylene) was determined in dependence on the type and the concentration of functional groups on the polymer surface. For this purpose the polymer surface was equipped with monotype functional groups. The first method to produce monotype functionalized surfaces was an introduction of O functional groups using an oxygen plasma treatment and converting these groups to OH groups applying a wet chemical reduction. In result of this two-step treatment the hydroxyl group concentration at the polymer surface could be increased from 3–4 to 10–14 OH groups/100 C atoms. The second method consists in the deposition of a 150 nm adhesion-promoting layer of plasmapolymers or copolymers onto the polymer surface using the pulsed plasma technique. For that purpose functional groups carrying monomers as allyl alcohol, allylamine and acrylic acid were used. Applying the plasma-initiated copolymerization and using neutral “monomers” like ethylene or butadiene the concentration of the functional groups was varied.
A correlation of peel strength with the ability of forming chemical interactions between Al atoms and functional groups was found: COOH > OH >> NH2 > H(CH2–CH2).
2514. Friedrich, J.F., R. Mix, and S. Wettmarshausen, “A new concept for adhesion promotion in metal-polymer systems by introduction of covalently bonded spacers at the interface,” J. Adhesion Science and Technology, 22, 1123-1143, (2008).
A new concept for molecular interface design in metal–polymer systems is presented. The main features of this concept are the replacement of weak physical interactions by strong covalent bonds, the flexibilization of the interface for compensating different thermal expansions of materials by using long-chain flexible and covalently bonded spacers between the metal and the polymer as well as its design as a moisture-repellent structure for hindering diffusion of water molecules into the interface and hydrolysis of chemical bonds. For this purpose, the main task was to develop plasmachemical and chemical techniques for equipping polymer surfaces with monotype functional groups of adjustable concentration. The establishing of monotype functional groups allows grafting the functional groups by spacer molecules by applying usual wet-chemical reactions. Four processes were favoured for production of monotype functional groups by highly selective reactions: the plasma bromination, the plasma deposition of plasma polymers, the post-plasma chemical reduction of O-functionalities to OH-groups, and the chemical replacement of bromine groups by NH2-groups. The grafting of flexible organic molecules as spacers between the metal layer and polymer improved the peel strength of the metal. To obtain maximal peel strength of aluminium coatings to polypropylene films and occurrence of cohesive failure in the polypropylene substrate, about 27 OH groups per 100 C-atoms or 6 COOH groups per 100 C-atoms were needed. Introducing C6–11-aliphatic spacers 1 OH or COOH group per 100 C-atoms contributed about 60% of the maximal peel strength of the Al–PP system, i.e. 2 or 3 spacer molecules per 100 C-atoms were sufficient for maximal peel strength.
712. Friedrich, J.F., W. Unger, A. Lippitz, L. Wigant, et al, “Differences in surface oxidation of PP by corona, spark, and low-pressure oxygen discharge treatments and the relevance to adhesion,” Presented at First International Congress on Adhesion Science and Technology, Oct 1995.
1892. Friedrich, J.F., W. Unger, A. Lippitz, et al, “The improvement in adhesion of polyurethane-polypropylene composites by short-time exposure of polypropylene to low and atmospheric pressure plasmas,” J. Adhesion Science and Technology, 9, 575-598, (1995) (also in Polymer Surface Modification: Relevance to Adhesion, K.L. Mittal, ed., p. 49-72, VSP, May 1996).
The surfaces of polymers, namely polypropylene, copolymers and blends, were exposed to low pressure oxygen and atmospheric pressure air plasmas to improve their adhesion to polyurethane adhesives. A correlation is attempted between lap shear strengths of polypropylene-polyurethane composites and the relevant XPS, AFM and NEXAFS data. It was found that plasma functionalization improved the adhesion to maximum values even when the time of exposure was low: 1 to 10 seconds for low pressure plasmas, and 0.1 to 1 seconds in case of atmospheric plasma jet treatments. Thus, high lap shear strengths were obtained at relatively small oxygen contents. The improvement in shear strength at short time plasma exposures seems to be correlated to the complete smoothening of the supermolecular structure of stretched polypropylene foils as shown by AFM. Valence band XPS and derivatization techniques revealed more details of the oxygen functionalization on polypropylene. NEXAFS experiments confirmed a re-orientation of bonds and segments of the macromolecules by plasma exposure which are assumed to be responsible for adhesion improvement.
<-- Previous | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | 69 | 70 | 71 | 72 | 73 | 74 | 75 | 76 | 77 | Next-->