Thin plasma polymerized layers of acrylic acid (PPAA) were deposited onto polyethylene and muscovite mica surfaces. Structure and surface properties of the deposited layer depend on the polymerization conditions. The content of carboxylic groups in the layer decreases, whereas the degree of crosslinking or branching increases, with increasing discharge power. A soft, sticky layer with a low contact angle against water is obtained when a low discharge power (5 W) is used. In contrast, a hard film with a rather high water contact angle is obtained when the discharge power is high (50 W). A surface force apparatus was employed to study some film properties including adhesion force, crack formation, and capillary condensation. The adhesion force between plasma polymerized acrylic acid layers prepared at a low discharge power is high in dry air. It decreases remarkably in humid air and no adhesion is observed in water. In dry air, the adhesion force between PPAA layers decreases as the discharge power increases.

Three nonpolar organic polymers containing small amounts of polar functionality were studied with regard to their surface characteristics. Two of the materials, potassium chlorate/sulfuric acid-oxidized polyethylene and poly(ethylene-co-acrylic acid) display variable surface polarities which can be reversibly accessed by heating films of the polymers in air or aqueous sodium hydroxide. Sodium-reduced Teflon–FEP did not exhibit this characteristic. A combination of contact angle, ESCA, and ATR IR data are used to display that the surface changes are caused by migration of functional groups within the outer few tens of angstroms of the surface.

The reaction of a radiofrequency-excited oxygen plasma with the surfaces of cured and uncured polymethylsiloxane produces intense hydroxylation of the surface region as followed by FMIR spectroscopy. Characteristic infrared features indicative of intraor intermolecular hydrogen bonding are evident. Plasma oxidation differs markedly from thermal oxidation processes. Reactions of polymethylsiloxane with nitrogen and air plasmas were also investigated and compared to corona reactions of oxygen, nitrogen, and air. In air corona, nitrogen moieties appear to be introduced. The behavior of polymethylsiloxane surfaces in oxidizing acids is also described.

Oxidative activation of resinous wood surfaces by a corona treatment to improve adhesive bonding was studied. It was found that the wettability of the veneers, including hardwoods, softwoods, and tropical woods increased with an increase in the degree of treatment, and the gluability increased rapidly after the initial mild treatment. To elucidate the nature of any chemical change occurring on the wood surface, the dyeing examination of the wood and its components with Schiff's reagent was made, and the results showed a higher dyeing ability for corona-treated samples compared to untreated ones, indicating that aldehyde groups increased by the corona treatment. The treatment affected the alcohol-benzene extractives, and oxidized them to produce aldehyde groups. Especially, the neutral fraction in the extractives was significantly affected. On the other hand, negligible chemical effects of the treatment on the surface modification of the wood's main components were seen. Both the untreated and corona-treated samples adsorbed basic dye to the same extent of coloration. Thus, no measurable carboxyl groups increased on the surface of the samples. It seems that an increase in the wettability of corona-treated wood veneers resulted mainly from the oxidation of the high hydrophobic surface layer of neutral fraction substances in the extractives, and from the reduction in their hydrophobicity. © 1993 John Wiley & Sons, Inc.
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.1993.070490714

Ni, Fe, Ti, Al, Au, and Cu were each evaporated and deposited onto both sides of polyethylene and poly(tetrafluoroethylene) (PTFE) films. Adhesive joint strengths of the different metal–polymer–metal composites were compared and subsequent surface modifications due to metalization were investigated. Studies show no change in wettability of polyethylene or PTFE after a metal layer was deposited onto their surfaces and subsequently removed. There was also no evidence of oxidation or unsaturation of the surface. Gel fractions of polyethylene show a definite correlation between joint strength and crosslink at the surfaces of the different metal–polymer composites. Metals forming the strongest joints with polyethylene yield the greatest amount of crosslinking. Conversely, metals forming the weakest joints result in the least amount of crosslinking.

The adhension between aluminum and poly(ethylene-co-vinyltrimethoxysilane) (EVS) and poly(ethylene-co-butylacrylate-co-vinyltrimethoxysilane) (EVSBA), respectively, have been studied. For comparison an ordinary low density polyethylene (LDPE), a poly(ethylene-co-butylacrylate) (EBA), and an ionomer regarded as a bonding polymer were studied as well. The peel strength of laminates obtained by pressing were measured by a T-peel test. The structure of the fracture surfaces were investigated by reflection-IR, ESCA, and SEM. The peel strength of the LDPE and the EBA samples were 100 and 700 N/m, respectively. Although the amount of vinylsilane was low, about 0.2–0.3 mol %, its presence had a pronounced influence on the adhesion: 1800 and 3000 N/m for EVS and EVSBA, respectively. This is even higher than the value observed for the ionomer, 1560 N/m. Although there was a marked difference in surface topology, the SEM and ESCA analysis showed that the fracture was cohesive for both EVS and EVSBA. Immersion in water at 85°C increased the peel strength even more, especially in the case of EVSBA (up to 9000 N/m), in contrast to what is normally observed with aluminum polyethylene laminates. The results suggest that strong and nonhydrolyzable bonds, e.g., covalent bonds, have been formed across the polymer-metal interface for the ethylene copolymers containing vinylsilane.

The strength of joints between Teflon FEP (Type A) and 500- to 1000-Å gold layers deposited by evaporation can be greatly increased if the Teflon surface is subjected to electron-beam bombardment prior to the evaporation process. Typically, joint strengths of about 60 kg/cm², approaching the bulk strength of Teflon, are obtained for treatments with electron-beam energies in the range of 5 to 20 keV and intercepted charge densities of about 5 X 10⁻⁶ C/cm². This compares with gold–Teflon joint strengths of about 10 kg/cm² for untreated material. The increase in joint strength is believed to be primarily due to crosslinking caused by the electron bombardment. Compared to the other known treatments to improve gold–Teflon joints, the present method has the advantage that the charge-storage properties of the Teflon are not irreversibly degraded. It is possible, for example, to store charge densities up to 3 X 10⁻⁸ C/cm², on 25-μm films treated with this method, with the same favorable charge-retention properties and thermally stimulated current characteristics as obtained for untreated Teflon.

The relationship between wetting and pressure-sensitive adhesion was studied using an adhesive composed of poly(butyl acrylate) and various adherends of different surface tension. The amount of adhesive deposit was determined quantitatively by tracer technique although the unbonding process was apparently observed as interface failure. The adhesive force and amount of deposit were both dependent on the critical surface tension of the adherends. Maximum tack value and contamination were observed with adherends whose critical surface tension was close to that but a little higher than that of the adhesive. The adhesive force obtained was lower than cohesive strength of adhesive. From this evidence, a mechanism for pressure-sensitive adhesion was discussed: the bond breaks in the addesive mass around the very minute spots where interaction is at work between adhesive and adherend. Inasmuch as the density of the minute spots per unit area depends on the surface tension, the adhesive force also depends on the surface tension.

For substrates such as polyesters having limited capacity for hydrogen bonding or other specific interactions, thermodynamic compatibility of the substrate and adhesive is shown to be a key factor in promoting bondability to the substrate. Such compatibility occurs, as shown by Abere, when the cohesive energy densities (CED) or solubility parameters (δ = √CED) of substrate and adhesive are matched. Investigations with polyester film-adhesive-film model systems with the use of a variety of nonpolar (hydrocarbon) and polar (chlorinated compounds, ethers, esters) adhesives illustrate how compatibility promotes bondability to poly(ethylene terephthalate). The poor adhesion of polyester fibers to resorcinol–formaldehyde–latex (RFL) adhesives is attributed to the incompatibility of resorcinol (δ = 16.0) with the polyester (δ = 10.3). Adhesion to RFL was improved by substituting the more compatible n-hexyl resorcinol (δ = 12.5) for resorcinol in RFL adhesives. Currently, the best adhesive systems for polyester tire yarns are those (e.g., isocyanate–epoxy) involving formation of urethane polymers having matching δ values with poly(ethylene terephthalate).

Effects of corona treatment and aging on commercially produced corona discharged polypropylene (PP) films were followed via surface sensitive roughness analysis by atomic force microscopy (AFM), water contact angle (WCA), and X-ray photoelectron spectroscopic (XPS) measurements. Roughness analysis by AFM gave similar results for both untreated and corona-treated samples. The measured water contact angle decreased after corona treatment but increased with aging. XPS findings revealed that corona treatment caused an increase in the O-containing species on the surface of the films, but the measured O/C atomic ratio decreased with aging. The angle dependence of the observed XPS O/C atomic ratio further revealed that surface modifications by the corona treatment were buried into the polymer away from the surface as a function of aging. This is attributed to a surface rearrangement of the macromolecules in agreement with the findings of Garbassi et al. on oxygen–plasma-treated polypropylene. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1846–1850, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819991114%2974%3A7%3C1846%3A%3AAID-APP29%3E3.0.CO%3B2-B

Corona discharge treatment was conducted for ultrahigh molecular weight polyethylene (UHMWPE) fiber. The functional groups and surface roughness of the polyethylene fiber surface were determined by an X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The interfacial shear strength of UHMWPE fiber with HDPE film was determined by microbond pullout method. The interfacial shear strength increased by corona treatment. Then, the effect of the chemical and physical factors on the interfacial shear strength was discussed based on the results of multivariate regression analysis. The results indicated that the contribution of functional groups and surface roughness to the interfacial shear strength was expressed as 50 and 50%, respectively. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 243–249, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819990110%2971%3A2%3C243%3A%3AAID-APP7%3E3.0.CO%3B2-I

Morphological and chemical changes of the surface of low-density polyethylene (LDPE), linear middle-density polyethylene (L-MDPE), and their 80/20 blend were studied by different techniques after corona-discharge treatment in air and subsequent annealing. The surface tension was determined by wetting; the roughness was measured by atomic force microscope (AFM), and the surface chemical composition was analyzed by X-ray photoelectron spectroscopy (XPS), whereas the low-molecular-mass fraction washed off by chloroform by FTIR. The surface tension of the films increases with the electrode current. The surface roughness depends primarily on the polymer type and is less affected by the corona treatment. At the initial stage of annealing, posttreatment-type oxidation and hydrophobic recovery are competing. The former is more pronounced in L-MDPE, the latter in LDPE. After annealing at 50°C for 160 days, hydrophobic recovery becomes predominant in each film studied, which is accompanied by significant smoothening of the surface. According to XPS and FTIR results, this is due to the migration of low-molecular-mass components (oligomers, oxidized polymer fractions, and additives) to the surface. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1529–1541, 2000
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2820000606%2976%3A10%3C1529%3A%3AAID-APP6%3E3.0.CO%3B2-J

Chemical etching, plasma, and ion beam treatments were used to modify the surface of Polytetrafluoroethylene (PTFE). Each surface treatment method developed different surface characteristics. In addition to morphological observation, contact angle, atomic chemical composition, and adhesion strength were measured after treatment with various methods. The different adhesion strengths were explained based on the morphology and atomic chemical composition of the treated PTFE surfaces. The chemical etching showed substantial defluorination, and the adhesion strength was fairly high. The argon plasma treatment introduced very large amounts of oxygen into the surface, and the surface was very smooth with a crater-like structure. Ion beam treatment induced a form of spires whose dimensions were of several micrometers, depending on the ion dose, whereas the oxygen plasma-treated samples showed short spires with spherical particles on the top. The spire-like surface morphology and increased surface area during bonding by ion beam treatment appear to be the reason for a higher adhesion strength than that of the oxygen plasma-treated PTFE. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1913–1920, 2000
https://onlinelibrary.wiley.com/doi/abs/10.1002/1097-4628%2820000829%2977%3A9%3C1913%3A%3AAID-APP7%3E3.0.CO%3B2-%23

Poly(vinylamine) (PVAm) was grafted on a poly(ethylene) (PE) film surface via the surface graft polymerization of N-vinylformamide (NVF) and N-vinylacetamide (NVA) and the subsequent hydrolysis of those grafted polymers. The surface was characterized by X-ray photoelectron spectroscopy (XPS), contact angle, moisture absorption, and the leakage of electrostatic charge from the films. PNVF and PNVA were introduced onto the surface of the PE film successfully, in spite of the fact that the initiator for polymerization was a peroxide group. The grafted amounts of PNVF and PNVA were dependent on the grafting time. A PVAm-grafted surface was obtained via the hydrolysis of the grafted PNVF. The grafted-PNVA was not hydrolyzed under mild hydrolysis. The obtained PVAm-grafted surface appeared to be useful for various applications, such as protein immobilization or chemical modification. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1583–1587, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819990620%2972%3A12%3C1583%3A%3AAID-APP11%3E3.0.CO%3B2-0

Adhesion properties between branched polyethylene (PE) and isotactic polypropylene (PP) were studied by a peel test and scanning electron microscopy. In this study, two types of branched PEs were used; one is a linear low density polyethylene (LLDPE) and the other is a high pressure low density polyethylene (LDPE). The adhesive strength of the LLDPE/PP is much higher than that of LDPE/PP. Furthermore, the formation of PE influxes between PP spherulites has a small effect on the adhesion. The dynamic viscoelastic measurements for the binary blends composed of branched PE and PP were also carried out to estimate the interfacial tension by using a rheological emulsion model proposed by Palierne. The interfacial tension is 1.0 mN for LLDPE/PP and 2.1 mN for LDPE/PP, suggesting that the interfacial thickness of LLDPE/PP is about twice that of LDPE/PP. The adhesive strength between branched PE and PP will be determined by the interfacial thickness, which represents the entanglements between two polymers. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 457–463, 1998
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819981017%2970%3A3%3C457%3A%3AAID-APP5%3E3.0.CO%3B2-M

Ion Irradiation on polytetrafluoroethylene(PTFE) has been carried out to improve adhesion to metal and to adhesive cement. Argon ion was irradiated on the polymer, and amount of Ar⁺ was changed from 10¹⁴ ions/cm² to l×10¹⁷ ions/cm² at 1 keV, and 4 ml/min of oxygen gas was flowed near the polymer surface during the ion irradiation. Wetting angle was changed from 100 degree to 70 - 150 degree depending on the ion beam condition. The changes of wetting angle and effects of Ar⁺ irradiation in oxygen environment were explained in a view of surface morphology due to the ion beam irradiation onto PTFE and formation of hydrophilic group due to a reaction between irradiated polymer chain and the blown oxygen. Strongly enhanced adhesions were explained by interlock mechanism, formation of electron acceptor groups on the modified PTFE, and interfacial chemical reaction between the irradiated surface and the deposited materials.

Modification of polyolefin surfaces is often necessary to achieve improved printability, lamination, etc. Although corona discharge and flame treatments can produce the higher surface energy needed for these applications, the properties of the resulting surfaces are not always optimal. Atmospheric pressure plasma is a surface modification technique that is similar to corona discharge treatment, but with more control, greater uniformity, and higher efficiency. Using an atmospheric pressure plasma unit with a dielectric barrier discharge generated using an asymmetric pulse voltage, the effects of different gases, powers, and linespeeds on polyethylene surface treatment were studied. Our results show that atmospheric pressure plasma can be used to achieve higher long-term wettability, higher surface oxygen and nitrogen, and a greater range of surface chemistries with better robustness versus standard corona treatment. Atomic force microscopy results suggest significant differences in the mechanism of surface functionalization versus etching and ablation depending on the gases used. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 319–331, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819990110%2971%3A2%3C319%3A%3AAID-APP16%3E3.0.CO%3B2-T

The effect of various corona treatment conditions on the mechanical properties of cellulose fibers/polypropylene composites was studied. The cellulose fibers and polypropylene were modified using a wide range of corona treatment levels and concentrations of oxygen. The treatment level of the fibers was evaluated using the electrical conductance of their aqueous suspensions. The mechanical properties of composites obtained from different combinations of treated or untreated cellulose fibers and polypropylene were characterized by tensile stress–strain measurements; they improved substantially when either the cellulose fibers alone or both components were treated, although composites made from untreated cellulose fibers and treated polypropylene showed a relatively small improvement. The results obtained indicate that dispersive forces are mostly responsible for the enhanced adhesion. The relationship between the electrical conductance of the fibers, the mechanical properties, and the mechanism of improved adhesion is discussed. © 1994 John Wiley & Sons, Inc.
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.1994.070530401

The surface degradation and production of low molecular weight oxidized materials (LMWOM) on biaxially oriented polypropylene (BOPP) and low-density polyethylene (LDPE) films was investigated and compared for two different dielectric barrier discharge (DBD) treatment types, namely air corona and nitrogen atmospheric pressure glow discharge (N₂ APGD). Contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) analyses were performed in conjunction with rinsing the treated films in water. It is shown that N₂ APGD treatments of both polyolefins result in much less surface degradation, therefore, allowing for a significantly higher degree of functionalization and better wettability. Hydrophobic recovery of the treated films has also been studied by monitoring their surface energy (γ_s) over a period of time extending up to several months after treatment. Following both surface modification techniques, the treated polyolefin films were both found to undergo hydrophobic recovery; however, for N₂ APGD modified surfaces, γ_s ceases to decrease after a few days and attains a higher stable value than in the case of air corona treated films. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1291–1303, 2004
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.21134

The effects of corona-discharge treatment (CDT) of commercial polyethylene (PE) Linear low-density PE (LLDPE) were studied with special emphasis on the heat-seal behavior of treated films. A range of treat levels, representative of those used in industry, was obtained by varying the applied power to a commercial, on-line treater. Film surfaces were characterized by XPS and wetting-tension measurements. The primary effect of CDT on the heat-sealing behavior of LLDPE films is a transition in the failure mode of heat seals from a normal tearing or inseparable bond to a peelable seal. In addition, CDT increases the seal initiation temperature 5–17°C and decreases the plateau seal strength 5–20% as the treat level, or wetting tension, increases from 31 to 56 dynes/cm. These effects are attributed to cross-linking during corona treatment, which restricts polymer mobility near the surface and limits the extent of interdiffusion and entaglements across the seal interface. Results of heat-sealing studies with electron-beam-irradiated PE, chemically oxidized PE, and CDT polypropylene (PP) provide indirect evidence for the proposed surface cross-linking mechanism. The effect of commercial levels of slip additives on the heat-seal behavior was also investigated. copy; 1994 John Wiley & Sons, Inc.
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.1994.070510113

The corona discharge technique was explored as a means of forming chemically active sites on a low-density polyethylene (LDPE) film surface. The active species thus prepared at atmospheric pressure in air was exploited to subsequently induce copolymerization of 2-hydroxyethyl methacrylate (HEMA) onto LDPE film in aqueous solution. The results showed that with the corona discharge voltage, reaction temperature, and inhibitor concentration in the reaction solution the grafting degree increased to a maximum and then decreased. As the corona discharge time, reaction time, and HEMA concentration in the reaction solution increased, the grafting degree increased. With reaction conditions of a 5 vol % HEMA concentration, 50°C copolymerization temperature, and a 2.0-h reaction time, the degree of grafting of the LDPE film reached a high value of 158.0 μg/cm² after treatment for 72 s with a 15-kV voltage at 50 Hz. Some characteristic peaks of the grafted LDPE came into view at 1719 cm⁻¹ on attenuated total reflectance IR spectra (CO in ester groups) and at 531 eV on electron spectroscopy for chemical analysis (ESCA) spectra (O_1s). The C_1s core level ESCA spectrum of HEMA-grafted LDPE showed two strong peaks at ∼286.6 eV (CO from hydroxyl groups and ester groups) and ∼289.1 eV (OCO from ester groups), and the C atom ratio in the CO groups and OCO groups was 2:1. The hydrophilicity of the grafted LDPE film was remarkably improved compared to that of the ungrafted LDPE film. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2881–2887, 2001
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.1738

A starch-based biodegradable (BD) low density polyethylene (LDPE) film can be directly printable without any corona treatment, unlike virgin LDPE film. Such a film shows poor adhesion and nail scratch resistance of the ink on the printed area of the film. In order to increase the adhesion and nail scratch resistance of the ink on the printed BD film, grafting of acrylonitrile onto the BD film is carried out. The polyacrylonitrile grafted BD film shows better adhesion, nail scratch resistance, and printability. The printability of the polyacrylonitrile grafted BD film is comparable to the conventional corona treated LDPE film. The extent of printability is a function of the surface smoothness, as well as the optimum percentage of grafting on the biodegradable film. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1273–1277, 2001
https://onlinelibrary.wiley.com/doi/abs/10.1002/1097-4628(20010214)79:7%3C1273::AID-APP150%3E3.0.CO;2-L

The interfacial shear strength of an ultrahigh molecular weight (UHMW) polyethylene (PE) fiber/epoxy-resin system was greatly improved by the corona-discharge treatment of the fiber. The UHMW PE-fiber/epoxy-resin composite was prepared with corona-discharge-treated UHMW PE fiber. The mechanical properties of the composite sheet were determined by tensile testing. The tensile strength of the composite was also very much improved. However, the tensile strength of the composite was about one-half of the theoretical strength. This result was due to the molecular degradation of the PE-fiber surface caused by surface modification. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1162–1168, 2001
https://onlinelibrary.wiley.com/doi/abs/10.1002/1097-4628%2820010214%2979%3A7%3C1162%3A%3AAID-APP20%3E3.0.CO%3B2-Y

Polyethylene, polypropylene, poly(vinyl fluoride) (Tedlar), polystyrene, nylon 6, poly(ethylene terephthalate) (Mylar), polycarbonate, cellulose acetate butyrate, and a poly(oxymethylene) copolymer were treated with activated helium and with activated oxygen. Mechanical strengths of adhesive-bonded specimens prepared from treated and from untreated coupons were compared. Polyethylene (PE) and polypropylene (PP) showed the greatest increases in bond strength. Oxygen and helium were both effective with polyethylene, but polypropylene showed no improvement when treated with activated helium. The results with excited helium parallel the effects of ionizing radiation on these two polymers, as does the appearance of unsaturation bands in the infrared (965 cm⁻¹ in PE, and 887 and 910 cm⁻¹ in PP). Active nitrogen produced excellent bond strength with polyethylene but not with polypropylene. Of the remaining polymers examined, Tedlar, polystyrene, and nylon 6 showed the greatest improvement in bondability after treatment, and Mylar showed moderate improvement. Polycarbonate, cellulose acetate butyrate, and the poly(oxymethylene) copolymer gave approximately two-fold increases in lap-shear bond strength. In several cases, significant differences in response to time of treatment and type of excited gas were found.

Contact angle measurements with three different liquids were performed on: (i) butyl rubber PB 101-3 (Polysar Ltd.) and (ii) Dow Corning 236 dispersion. Contact angles were measured at different temperatures within the range from 23°C (room temperature) to 120°C. The surface tensions, γsv, of the polymeric coatings at each temperature were calculated from the contact angles. The temperature coefficients of the surface tensions, d_γsv/dT, i.e., the surface entropies, were established for the temperature range covered.

Low-rate dynamic contact angles on poly(t-butyl methacrylate) (PtBMA) were measured by an automated axisymmetric drop shape analysis profile (ADSA-P). The solid surface tension of PtBMA is calculated to be 18.1 mJ/m², with a 95% confidence limit of ±0.6 mJ/m². This value was compared to previous results with different homopolymeric polymethacrylates [poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(n-butyl methacrylate) (PnBMA)] and with copolymeric polymethacrylates {poly(methyl methacrylate/ethyl methacrylate, 30/70) [P(MMA/EMA, 30/70)] and poly(methyl methacrylate/n-butyl methacrylate) [P(MMA/nBMA)]}. It was found that increasing length and size of the alkyl side chain decrease the solid surface tension, as expected. Comparison with pure alkyl surfaces suggests that the surface tension of PtBMA is dominated by the very hydrophobic t-butyl group. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2493–2504, 2000
https://onlinelibrary.wiley.com/doi/abs/10.1002/1097-4628%2820000912%2977%3A11%3C2493%3A%3AAID-APP19%3E3.0.CO%3B2-H

Poly(tetrafluoroethylene) and a fluoroethylene copolymer were surface treated with a 2.45-GHz microwave plasma to enhance their adhesion to a vinylester thermoset. The plasmas were generated with an inert gas (Ar) and with reactive gases (H₂, O₂, and N₂). The lap-joint shear stress was measured on fluoropolymer samples glued with the vinylester. In general, the stress at failure increased with increasing plasma-energy dose. The H₂ plasma yielded the best adhesion, and X-ray photoelectron spectroscopy revealed that it yielded the highest degree of defluorination of the fluoropolymer surface. The defluorination efficiency declined in the order H₂, Ar, O₂, and N₂. Contact angle measurements and scanning electron microscopy revealed that the surface roughness of the fluoropolymer depended on the rate of achieving the target energy dose. High power led to a smoother surface, probably because of a greater increase in temperature and partial melting. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 838–842, 2005
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.22174

Tetrafluoroethylene–hexafluoropropylene (FEP) copolymer sheets were modified by remote H₂, N₂, O₂, and Ar plasmas, and the effects of the modification on adhesion between FEP sheets and copper metal were investigated. The four plasmas were able to modify the FEP surfaces' hydrophilicity. Defluorination and oxidation reactions on the FEP surfaces occurred with exposure to the plasma. The hydrophilic modification by H₂ plasma was best, followed by modification by O₂, Ar, and N₂ plasmas. The surface modification of FEP by all four remote plasmas was effective in improving adhesion with copper metal. The peel strength order of the FEP/Cu adhesive joints was H₂ plasma > Ar plasma > N₂ plasma > O₂ plasma. Mild surface modification is important for the adhesion improvement of FEP with Cu metal. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1258–1267, 2002
https://onlinelibrary.wiley.com/doi/10.1002/app.2293

The surfaces of polyester (PET) fabrics and foils were modified by low-pressure RF plasmas with air, CO₂, water vapor as well as Ar/O₂ and He/O₂ mixtures. To increase the wettability of the fabrics, the plasma processing parameters were optimized by means of a suction test with water. It was found that low pressure (10–16 Pa) and medium power (10–16 W) yielded a good penetration of plasma species in the textile structure for all oxygen-containing gases and gaseous mixtures used. While the wettability of the PET fabric was increased in all cases, the Ar/O₂ plasma revealed the best hydrophilization effect with respect to water suction and aging. The hydrophilization of PET fabrics was closely related to the surface oxidation and was characterized by XPS analysis. Static and advancing contact angles were determined from the capillary rise with water. Both wetting and aging demonstrated a good comparability between plasma-treated PET fabrics and foils, thus indicating a uniform treatment. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1452–1458, 2006
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.24308

The effects of argon glow discharge and selected organic solvents on the surface wettability of poly(ethylene terephthalate) (PET) and on the wettability decay of glow discharged PET films were studied. Glow discharge in argon (30 W/1 min) drastically reduced the initial water contact angle (CA) measurement of PET from 67.0 to 26.2°. The glow-discharge-induced wetting, however, decayed during the first 7 days and stabilized at 33.1°. Treatments in dimethyl sulfoxide, dimethyl formamide, pyrdine, and water at 80°C caused some improvement in surface wettability as shown by decreases of water CAs in the range of 53–56°. When the solvent and glow discharge treatments were applied consecutively on PET, additive effects on improving surface wettability were observed. The stabilized water CAs of the solvent-and-glow-discharged films ranged from 25.0 to 32.1° depending upon the solvent type. The solvent treatments prior to glow discharge either reduced the extent of CA decay or the time taken to reach stabilization on PET films. Scanning electron microscopic evaluation showed no difference between the solventtreated and the untreated PET surfaces, but a finely etched surface was observed on the glow discharged PET at a 40,000 magnification and above. The distinctly different surface of the DMSO-and-glow-discharged PET indicated that morphological changes on PET surface were induced by the solvent.

Gas plasma treatment of poly(ethylene terephthalate) nonwoven (NW–PET) was used to increase the hydrophilicity of single- and multilayer NW–PET. NW–PET was treated with a pulsatile CO₂ or with a pulsatile H₂O glow discharge. X-ray photoelectron spectroscopy (XPS) showed significantly more oxygen with CO₂ glow-discharge-treated NW–PET than with H₂O glow-discharge-treated-NW–PET surfaces. Moreover, the introduction rate of oxygen at a single layer of NW–PET was higher for a CO₂ than for a H₂O glow-discharge treatment. Titration data revealed significantly higher surface concentrations of carboxylic groups for CO₂ glow-discharge NW–PET than for H₂O glow-discharge-treated NW–PET. Mass spectrometry analysis revealed that the entire internal surface of a single layer of NW–PET was modified. XPS and contact measurements confirmed the modification of the internal surface of multilayers of NW–PET. H₂O and CO₂ glow-discharge-treated substrates consisting of six layers of NW–PET had a nonuniform surface concentration of carboxylic acid groups as determined with titration experiments. The outside layers of the substrate contained a higher surface concentration of carboxylic acid groups than did the inside layers. XPS analysis and titration data showed that the rinsing of H₂O and CO₂ glow-discharge-treated NW–PET with water changed the surface composition considerably. Part of the carboxylic acid group-containing species were washed off. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 480–494, 2000
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1097-4628(20000124)75:4%3C480::AID-APP3%3E3.0.CO;2-9

Plasma-treated poly-p-xylylene films have been characterized by neutron activation oxygen analysis, internal reflection (IRS) and transmission infrared spectroscopy, transmission electron microscopy (TEM), and surface contact angle measurements. The results indicate that an oxygen plasma roughens the surface and that oxygen is incorporated into the surface. Oxygen is not detected in the bulk of the sample. The infrared transmission spectra exhibited no carbonyl band, but the relative band intensities changed, indicating a change in ring substitution by a loss of chlorine in the chlorinated poly-p-xylylenes. The IRS spectra of the surface of films treated with oxygen plasma did contain carbonyl bands at 1730 and 1640 cm⁻¹. Argon and helium plasmas generally decreased the water contact angle measured on plasma-treated poly-p-xylylene surfaces more than oxygen or nitrogen plasma treatments. Regardless of the plasma utilized, the water contact angles increased with time after the treatment but did not recover to the original level. IRS spectra of the surface of films treated with argon plasma contained carbonyl bands at 1730 and 1695 cm⁻¹. The adhesion of a polyurethane thermosetting material to a poly-p-xylylene surface is greatly improved if a plasma treatment is used prior to the application of the polyurethane. The degree of improvement in adhesion was dependent on the type of plasma and the treatment time.

The dispersion force component of surface free energy, γ, and the nondispersive interaction free energy between solid and water, I, were determined by the two-liquid contact-angle method, i.e., by the measurement of contact angles of water drops on plain solids in hydrocarbon, for commercialy available organic polymers such as nylons, halogenated vinyl polymers, polyesters, etc. A method to estimate the I values from the knowledge of the polymer composition is also proposed, on the basis of the assumption of the spherical monomer unit and the sum of interactions between functional groups and water molecules at the surface.

The fiber/epoxy resin adhesion increases after plasma treatment on ultrahigh molecular weight polyethylene (UHMW-PE) fibers. The surface modification of UHMW-PE monofilaments was studied using a combination of techniques: contact-angle measurements, SEM, and pullout tests. The results may be summarized as follows: Infiuenced by different plasma parameters and draw ratios of the monofilaments, the adhesion increases by at least four times by plasma treatment. Failure in the pullout tests involve rupture within a treated monofilament and the skin of it was peeled off; the degree of peeling-off is affected by different plasma treatment conditions and draw ratios of the monofilaments. There is only a slight decrease in the surface energy of the treated monofilaments with aging time. Ways of combining plasma etching with other chemical treatments to further improve the fiber/resin adhesion have also been studied. © 1993 John Wiley & Sons, Inc.
https://onlinelibrary.wiley.com/doi/abs/10.1002/app.1993.070471116

Polymer films of poly(ethylene terephthalate), polypropylene, and cellophane were surface treated with tetrafluoromethane plasma under different time, power, and pressure conditions. Contact angles for water and methylene iodide and surface energy were analyzed with a dynamic contact angle analyzer. The stability of the treated surfaces was investigated by washing them with water or acetone, followed by contact angle measurements. The plasma treatments decreased the surface energies to 2–20 mJ/m² and consequently enhanced the hydrophobicity and oleophobicity of the materials. The treated surfaces were only moderately affected after washing with water and acetone, indicating stable surface treatments. The chemical composition of the material surfaces was analyzed with X-ray photoelectron spectroscopy (XPS) and revealed the incorporation of about 35–60 atomic % fluorine atoms in the surfaces after the treatments. The relative chemical composition of the C ls spectra's showed the incorporation of —CHF— groups and highly nonpolar —CF₂— and —CF₃ groups in the surfaces and also —CH₂—CF₂— groups in the surface of polypropylene. The hydrophobicity and oleophobicity improved with increased content of nonpolar —CF₂—, —CF₃, and —CH₂—CF₂— groups in the surfaces. For polyester and polypropylene, all major changes in chemical composition, advancing contact angle, and surface energy are attained after plasma treatment for one minute, while longer treatment time is required for cellophane. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1591–1601, 1997
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1097-4628(19971121)66:8%3C1591::AID-APP21%3E3.0.CO;2-5

The surface of poly(ethylene terephthalate) (PET) film was modified by low-temperature plasma with O₂, N₂, He, Ar, H₂, and CH₄ gases, respectively. After being treated by low-temperature plasma, their surface wettability and chemical composition were investigated by means of electron spectroscopy for chemical analysis (ESCA) and contact angle measurement. The result shows that the surface wettability of PET can be improved by low-temperature plasma, and the effect of the modification is due mainly to the kind of the gases. Mainly because of the contribution of hydrogen bonding force γ[STACK]^c_S[ENDSTACK], the surface wettability of PET treated with O₂, N₂, He, and Ar plasma for a short time (3 min) increase sharply, and the surface wettability is also improved by H₂ plasma treatment; but the CH₄ plasma treatment does not improve the wettability of PET. ESCA shows that the effect of wettability of PET is tightly related to the presence of polar functional groups that reside in the outermost surface layer of PET. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1327–1333, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/%28SICI%291097-4628%2819990606%2972%3A10%3C1327%3A%3AAID-APP13%3E3.0.CO%3B2-0

The surface free energy and surface structure of poly(tetrafluoroethylene) (PTFE) film treated with low temperature plasma in O₂, Ar, He, H₂, NH₃, and CH₄ gases are studied. The contact angles of the samples were measured, and the critical surface tension γ_c (Zisman) and γ_c (max) were determined on the basis of the Zisman's plots. Furthermore, the values of nonpolar dispersion force γ^a_s, dipole force γ^b_s, and hydrogen bonding force γ^c_s to the surface tensions for the plasma-treated samples were evaluated by the extended Fowkes equation. Mainly because of the contribution of polar force, the surface free energy and surface wettability of PTFE film which was treated with H₂, He, NH₃, Ar, and CH₄ for a short time increased greatly. Electron spectroscopy for chemical analysis (ESCA) shows that the reason was the decrease of fluorine and the increase of oxygen or nitrogen polar functional group on the surface of PTFE. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1733–1739, 1997
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1097-4628(19970328)63:13%3C1733::AID-APP4%3E3.0.CO;2-H