Ultra-high modulus polyethylene (UHMPE) fibres have been treated using a novel 'non-plasma' treatment allowing the incorporation of various chemical functional groups onto the polymer surface. The process comprises two steps: corona discharge treatment, followed by silanization of the polymer surface by a solution of an organo-functional silane. Corona discharge treatment incorporates oxygen-containing functionalities, e.g. reactive hydroxyl groups, onto the polymer surface. The presence of reactive -OH groups provides the possibility of covalent linkage of any organo-functional silane to the corona discharge-treated polymer in the form of a fibre, film, sheet, or powder. The effectiveness of the process was assessed by examining the interlaminar fracture energy and flexural modulus and by SEM analysis of the fracture surfaces of composites fabricated from the untreated, corona discharge-treated, ammonia plasma-treated, and the amine-grafted (using the novel process) UHMPE fabric. A significant improvement in interfacial adhesion was confirmed by increases in the interlaminar fracture energies and flexural moduli. The effectiveness of the process investigated is similar to the ammonia plasma treatment. SEM analysis of the fracture surfaces indicated a change in the fracture mode from purely adhesive for unmodified fibres, through to mixed failure mode for corona-treated material, to highly cohesive-in-fibre surface for amine-grafted UHMPE fibres. XPS analysis confirmed the incorporation of the amine groups onto the surface of polyethylene treated using the novel method.

This paper reviews the theoretical principles of macromolecular design of polymer interface/interphase systems for obtaining maximum adhesion. Subsequently, a relatively simple and industry-feasible technology for surface grafting connector molecules is discussed in detail and supported by a range of experimental examples. It is shown, in agreement with contemporary theory, that the use of chemically attached graft chemicals of controlled spatial geometry and chemical functionality enables a significant increase in the strength and fracture energy of the interphase, to the point of cohesive fracture of the substrate, or that of an adjacent medium such as adhesives, paints or elastomers. This occurs even after prolonged exposure of bonded or painted materials to adverse environments such as hot water, thermal shock, UV radiation and other hostile ambients.

Surface modifications of polyetheretherketone (PEEK) made by chemical etching or oxygen plasma treatment were examined in this study. Chemical etching caused surface topography to become irregular with higher roughness values R_a and R_q. Oxygen plasma treatment also affected surface topography, unveiling the spherulitic structure of PEEK. R_a, R_q and surface area significantly increased after plasma treatment; topographical modifications were, nonetheless, moderate. Wetting angle measurements and surface energy calculations revealed an increase of wettability and surface polarity due to both treatments. XPS measurements showed an increase of surface oxygen concentration after both treatments. An O:C ratio of 3.10 for the plasma-treated PEEK surface and 4.41 for the chemically-etched surface were determined. The results indicate that surface activation by oxygen plasma treatment for subsequent coating processes in supersaturated physiological solutions to manufacture PEEK for biomedical appiications is preferable over the chemical etching treatment.

This invention relates to a process for preparing poly: vinylbutyral sheeting which has a decreased tendency to block. More specifically, this invention relates to treating polyvinylbutyral by electrical discharge in a nitrogen atmosphere and thereby obtaining a surface on the sheeting that has a decreased tendency to adhere to itself or to other similarly treated polyvinylbutyral sheets.

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.

The bondability of the following polymers as a function of length of exposure to excited helium or oxygen was investigated: low-density polyethylene, high-density polyethylene (two types), poly(4-methyl-1-pentene), poly(vinyl fluoride), poly(vinylidene fluoride), FEP Teflon, poly(oxymethylene) copolymer, nylon 6, nylon 66, poly(ethylene terephthalate), and polystyrene. Generally, the bond strength increase rapidly initially and then remains nearly constant, perhaps decreasing in some cases at long exposure times. A method is presented for calculating bond strength-versus-exposure time curves. The calculated curves generally fit the data reasonably well. Polypropylene showed a rapid increase in bondability with exposure to excited oxygen. Helium was ineffective toward this polymer under normal conditions, but could produce good bond strength at higher temperatures.

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.

Frequently we experience the existance of adhesive forces between small particles. It seems natural to ascribe this adhesion for a large part to London-v.d. Waals forces. To obtain general information concerning their order of magnitude the London-v. d. Waals interaction between two spherical particles is computed as a function of the diameters and the distance separating them. A table is calculated which enables numerical application of the formulae derived. Besides approximations are added, which may be used when the distance between the particles is small. In a separate section it is investigated how the results must be modified, when both particles are immersed in a liquid. Here we are led to the important conclusion that even in that case London-v. d. Waals forces generally cause an attraction.

The finding that the dispersion force contributions to the surface free energies of octane and water are equal enabled a simple method to be developed to characterize the hydrophilic nature of solid surfaces. This technique involves measuring octane contact angles on solid surfaces under water. Nonhydrophilic solids unable to interact by polar forces exhibit a predicted 50° contact angle, whereas those able to interact by polar forces give values greater than 50°. The greater the contact angle, the stronger are the polar interactions. The deviation of the contact angle from 50° can be used to evaluate, Isw, defined as the interfacial stabilization energy from the nondispersion (polar) forces.

The dispersion force contributions to the surface free energies of octane and water are equal—21.8 dyn/cm. Octane's surface free energy has no polar component, whereas water has a polar contribution of 50.2 dyn/cm. Therefore, the increase in the contact angle of octane on various polar polymer surfaces underwater is a quantitative measure of the interfacial stabilization energy from polar forces. Octane contact angles were measured underwater on polyethylene, polytetrafluoroethylene, and polyethyleneglycolterephthalate surfaces before and after surface oxidation in a low temperature asher. The octane contact angles increased in each case as the surfaces became oxidized. When simple lap joints were prepared from these polymers and then broken in an Instron Tester, the measured breaking forces correlated well with the octane contact angles. Breaking strength increases of 1.1, 1.2, and 1.8 psi were realized with the polyethylene, polytetrafluoroethylene, and polyethyleneglycolterephthalate, respectively, when the polar forces were increased by 1 erg/cm².

A treater system includes a conductive roller electrode that supports a moving web that is to be treated. One or more active electrode assemblies mounted to support headers have a pair of active electrodes that are positioned to treat one surface of the web as the web passes over the roller electrode. Air or a gas/gas mixture can be selectively piped to a chamber adjacent the active electrodes and diffused along the length of the discharge surfaces to allow the treater to operate in three distinct modes: corona, chemical corona and atmospheric plasma. The active electrodes are cooled by passing air into and through tubular bodies of the active electrodes.

This chapter discusses the physicochemical principles of surface phenomena, and provides an overview of the research regarding surface properties of biopolymers used for the manufacturing of biodegradable films. Surface properties of food packaging polymers, such as wettability, scalability, printability, dye uptake, resistance to glazing, and adhesion to food surfaces or other polymers are of central importance to food packaging designers and engineers with respect to product shelf-life, appearance, and quality control. The most commonly used food packaging polymers are low-density polyethylene, high-density polyethylene, polypropylene, polytetrafluoroethylene, and nylon. In recent years, environmental concerns have increased the interest in preparing biodegradable packaging materials. Proteins and polysaccharides are the biopolymers of prime interest, since they can be used effectively to make edible and biodegradable films to replace short shelf-life plastics. Surface properties of biopolymers provide a supplementary understanding of film behavior, leading to an enhanced design of packaging materials for specific applications.

Polyvinylidenefluoride (PVDF) was irradiated by a keV Ar⁺ ion in O₂ environment for improving adhesion between PVDF and Pt, and reaction between PVDF and the ion beam has been investigated by X-ray photoelectron spectroscopy (XPS). The adhesion test between Pt and the modified PVDF was carried out by boiling test, in which the specimens were kept in boiling water for 4 h. Two failure modes (buckling up due to weak adhesion and crack formation due to strong adhesion) of Pt films have been observed in the system. Contact angle of PVDF was reduced to 31 from 75° by the irradiation of 1 × 10¹⁵ Ar⁺ ions/cm² with oxygen flow rate of 8 sccm. The surface of the irradiated PVDF became more rough as ion dose increased. The improved adhesion mechanism and identification of newly formed chemical species have been confirmed by Carbon 1s and Fluorine 1s X-ray photoelectron core-level spectra. The main reaction occurred at the irradiated PVDF surface is an ion-beam-induced oxidation accompanied with preferential sputtering of fluorine. Newly formed chemical species at interface are regarded as ester and carboxyl groups. Adhesion of the Pt–PVDF interface was improved by ion irradiation in O₂ environment. This improvement is originated from the presence of carbon—oxygen bonds on the irradiated PVDF surface. Comparison of failure modes on the irradiated PVDF at various conditions after the boiling test shows that adhesion of Pt film is largely affected by the product of ion-assisted reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 41–47, 1999
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1097-4628(19990404)72:1%3C41::AID-APP4%3E3.0.CO;2-J

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

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

Surface tensions of polymers can be accurately determined by observing whether droplets of liquids spontaneously spread or not. The polymer surface tension will be higher than the surface tension of a liquid which spreads, and lower than that of a liquid which remains as a droplet.

Examples of surface characterization using cohesive energy parameters and surface energy parameters are given. In general the two approaches yield essentially equivalent results. The predictive ability of the cohesive energy approach suggests its use where directed modification of surface properties is desired.

The aim of this work was to improve adhesion to tefzel using plasma surface treatment. The plasmas used were O₂, and NH₃. Joints ,ade from the adherends using several commercially available epoxy adhesives were tested using a double lap shear configuration. Measured bond strenghts for the treated adherends were as much as 30 times greater than those for the untreated materials. Examination of the O₂ plasma-treated Tefzel by electron spectroscopy for chemical analysis indicated a surface oxidation increase of about 7–8% over the untreated material, with the oxide being primarily in the form of an ester.

A stream of atomic oxygen, produced by passing oxygen at low pressure through a radio-frequency coil, was allowed to impinge on films prepared from several dozen different polymers. The flow of oxygen radicals was regulated so that the reaction temperatures were between 40 and 70°C. The rapid reactions which occurred at the polymer film–oxygen radical interface were essentially unaffected by the presence of phenolic antioxidants over a wide range of concentrations but rate of reaction was greatly affected by the structure of the polymer. Bulk properties of the polymers were unchanged because the attack by atomic oxygen is limited to the surface of the polymer. In many instances a simple ablation of the surface was observed, but in some cases, especially polyethylene and polypropylene, a highly oxidized surface layer was created. These oxidized surface layers had remarkably low contact angles with water and should be of great interest in improving adhesion and other surface-dependent properties of polymers.

Contact time of activated gas with polymer film of as little as 1 sec. under these relatively mild conditions resulted in greatly improved adhesive joint strength for polyethylene. Longer contact times were required for polymers such as polytetrafluoroethylene. Helium, argon, krypton, neon, and xenon, and even hydrogen and nitrogen were all effective crosslinking agents although the latter also changed wettability of the surface. Adhesive joints were prepared by sandwiching 1041 films of polyethylene (Marlex 5003, Phillips Petroleum Co., Bartlesville, Oklahoma) and polytetrafluoroethylene (G-80, Allied Chemical Co., Morristown, New Jersey), before and after CASING, between epoxy-coated aluminum strips (3). The values obtained for tensile shear strengths of these joints are shown in Figure 1. In these instances, the polyethylene film was treated for 10 sec. and the polytetrafluoroethylene film was treated for 10 min.

Plasticizer migration from plastics, particularly in polar polymers like flexible PVC, poses significant health risks, including endocrine disruption and carcinogenicity. This review article consolidates research on surface modification techniques aimed at suppressing plasticizer migration, which are crucial for minimizing health and environmental hazards. Over the past decade, substantial advancements have been made in this field. Physical irradiation methods, including plasma, ultraviolet, and gamma-ray irradiation—induce surface cross-linking, forming a three-dimensional network that reduces plasticizer migration by up to 80 %, as demonstrated by DEHP loss decreasing from 5.6 to 1.2 mg/cm2 in modified PVC. Chemical grafting techniques covalently attach hydrophilic groups or polymer chains, which interact with plasticizers via hydrogen bonding and van der Waals forces, achieving a 75 % reduction in migration, for example, DEHP leaching from 250 mg to 52 mg. Solution coating methods, particularly protein-based coatings, show exceptional performance with up to 93 % inhibition, reducing DEHP migration from 60 ppm to 4.2 ppm. Despite these achievements, challenges persist in enhancing coating durability, reducing costs, and minimizing environmental risks. Future research directions should focus on improving the long-term stability of coatings, refining experimental methodologies, and establishing robust evaluation standards. This work aims to provide a critical reference for the development of safer plastic applications in healthcare and food packaging industries, offering insights into the design and implementation of effective surface modification strategies to address the ongoing issue of plasticizer migration in plastic materials.

This is all about dynes. The dyne level of a material is called its surface energy. If the liquid has a dyne level lower than the material's surface energy, then the liquid will spread out over its entire surface in a uniform wet layer. If the ink's dyne level is equal to or higher than a material's dyne level, the liquid will become cohesive and tend to remain in droplets. So, dyne level refers to the measurement of surface energy of a material or substrate and can be a good indicator of our chances for successful adhesion. Different chemistries of adhesives are required for bonding substrates depending on their dyne level which is evident when applying a coating to a paper based product versus plastic or glass. Coatings on some materials might adhere quickly or beadup like water on glass if not compatible. Typically, lower dyne levels of 30 or less indicate that a liquid adhesive would bead-up on the surface, compared to higher dyne levels of 38 or more which indicate reasonable bonding properties. While this is one indicator of successful bonding compatibility, it does not guarantee reliable surface adhesion. But there are different means to improve adhesion based on surface preparation, improved adhesives or a combination of both.