Surface Free Energy Of Polymers Research Articles

Effect of Tacticity on London Dispersive Surface Energy, Polar Free Energy and Lewis Acid-Base Surface Energies of Poly Methyl Methacrylate by Inverse Gas Chromatography

This research was devoted to study the effect of the tacticity on the surface physicochemical properties of PMMA. (1) Background: The determination of the surface free energy of polymers is generally carried out by inverse gas chromatography (IGC) at infinite dilution. The dispersive, polar and surface acid-base properties of PMMA at different tacticities were obtained via IGC technique with the help of the net retention time and volume of adsorbed. (2) Methods: The London dispersion equation was used to quantify the polar free energy of adsorption, while the London dispersive surface energy γsd(T) of PMMAs was determined using the thermal model. (3) Results: The results showed non-linear variations of γsd(T) of atactic, isotactic, and syndiotactic PMMAs with three maxima characterizing the three transition temperatures of PMMAs. The obtained values of the enthalpic and entropic Lewis’s acid-base parameters showed that the basicity of the atactic PMMA was about four times larger than its acidity. (4) Conclusions: A large difference in the behavior of the various PMMAs was proven in the different values of the polar acid and base surface energies of the three PMMAs with an important effect of the tacticity of PMMA on its acid-base surface energies.

The Influence of Polycation and Counter-Anion Nature on the Properties of Poly(ionic liquid)-Based Membranes for CO2 Separation.

The current investigation is focused on the development of composite membranes based on polymeric ionic liquids (PILs) containing imidazolium and pyridinium polycations with various counterions, including hexafluorophosphate, tetrafluoroborate, and bis(trifluoromethylsulfonyl)imide. A combination of spectroscopic methods was used to identify the synthesized PILs and characterize their interaction with carbon dioxide. The density and surface free energy of polymers were performed by wettability measurements, and the results are in good agreement with the permeability and selectivity obtained within the gas transport tests. It was shown that the membranes with a selective layer based on PILs exhibit relatively high permeability with CO2 and high ideal selectivity CO2/CH4 and CO2/N2. Additionally, it was found that the type of an anion significantly affects the performance of the obtained membranes, with the most pronounced effect from bis-triflimide-based polymers, showing the highest permeability coefficient. These results provide valuable insights into the design and optimization of PIL-based membranes for natural and flue gas treatment.

Application of Nitrogen Piezoelectric Direct Discharge for Increase in Surface Free Energy of Polymers

The subject of this study is the application of the piezoelectric direct discharge (PDD) operated with nitrogen to control the surface free energy (SFE) of polymers. The activation area, defined as the area of the zone reaching the SFE of 58 mN/m for high-density polyethylene (HDPE) and poly (methyl methacrylate) (PMMA), is characterized. For HDPE, the activation area was characterized as a function of the distance from 1 to 16 mm, the nitrogen flow from 5 to 20 SLM, and the treatment time from 1 to 32 s. For larger distances, where SFE does not exceed 58 mN/m, the water contact angle is evaluated. The activation area for nitrogen PDD is typically a factor of 3 higher than for air with all other conditions the same. A maximum static activation area of 15 cm2 is reached. The plasma treatment of lens panels made of PMMA is presented as application example.

The study of laser transmission joining PA66 and PVC with large compatibility difference

On account of the large compatibility difference between Polyamide 66 (PA66) and Polyvinyl chloride (PVC), it is difficult to weld them directly by laser. The magnetron sputtering technology is introduced in this paper by which the transparent PVC is successfully welded with PA66 sputtered a 20μm-thick aluminum thin film as the transition and absorbed layer. In terms of the generation of bubbles, the distribution of aluminum atoms, the increasing of polymer surface free energy and the formation of new chemical bonds, this paper analyzes the mechanism why the two different materials can be welded successfully. The influences of bubbles and aluminum atoms on the performance of the joints are investigated via the optical microscope, revealing the micro anchor effect of high pressure homogeneous bubbles generated in the welding process and the improvement of material compatibility resulting from the addition of aluminum atoms. The surface contact angle meter is used to analyze the effect of coating on the surface free energy of polymer, and X-ray Photoelectron Spectrometer (XPS) is used to detect the chemical bond information of fracture sections on PVC. It is revealed that the increasing of coated PA66 surface free energy and the generation of new chemical bonding (Al-Cl) are the key to weld successfully. Finally, the mathematical model of process parameters is established by response surface method, and the optimal combination of process parameters is obtained.

In situ enhancement of the surface free energy and polarity of polymers by electrocapillary rise wetting

By applying the electrocapillary rise wetting, ECRW, with varied voltages and solvents to wet lignin and polyacrylonitrile, PAN, respectively, this work proven that this method can in situ enhance the surface free energy and polarity of polymers. Results showed that the voltage increase can in situ enhance the adsorption of only polar solvent by polymer to lead the reduction of related contact angle because of the adsorption of non-polar solvent by polymer ignoring the voltage variety. The diiodomethane was greatly adsorbed by both lignin and PAN due to the surface free energy of these polymers dominated by the non-polar Lifshitz-van der Waals interaction component. The voltage increase would enhance the Lewis acid-base interaction component of polymer to cause the enhancement of the surface free energy and polarity of polymers. This work showed that the polymer structure corresponding to the Lewis base may have different electric responses because the voltage increase has been found to cause the Lewis base component enhancement for ring structure-based polymer, e.g. lignin, and reduction for isotacticity structure-based polymer, e.g. PAN.

多層カーポンナノチューブの分散性とコンポジットの導電'性に及ぼすポリマーの表面自由エネルギーの影響

多層カーポンナノチューブの分散性とコンポジットの導電'性に及ぼすポリマーの表面自由エネルギーの影響

Investigation of the surface properties of POSS-modified polyacrylate by inverse gas chromatography

AbstractThe surface properties of poly(methyl methacryl-ate-co-n-butyl methacrylate-co-cyclopentyl methacryloxy propyl-polyhedral oligomeric silsesquioxane) (poly(MMA-co -BMA-co-POSSMA)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, such as the dispersive component of the surface energy, the specific interaction contribution to the free energy of adsorption and the acid/base constants of polymer surface were determined. It was found that incorporation of POSSMA into polymer resulted in increasing interactions between polymers and solvents, dispersive component of surface free energy of polymer and acidity of the surfaces of the polymers. The more the POSSMA were embedded, the larger the dispersive component of the surface free energy was, and the acidic character of the polymer surface was more obvious.

Surface modification and adhesion improvement of polyester films

Abstract Facile surface modification of polyester films was performed via chemical solutions treatment. Surface hydrolysis was carried out by means of sodium hydroxide solutions, leading to the formation of carboxylate groups. Three commercial polyester films of 100 μm in thickness were used in this work: AryLite™, Mylar™, and Teonex™, hydrolysis time being the main modification parameter. FTIR-ATR analysis, topography and contact angle (CA) measurements, surface free energy (SFE) and T-Peel adhesion tests were carried out to characterize the modified films. A quantitative estimate of the carboxylates surface coverage as a function of treatment time was obtained through a supramolecular approach, i.e. the ionic self-assembly of a tetracationic porphyrin chromophore onto the film surface. The surface free energy and critical surface tension of the hydrolyzed polyesters was evaluated by means of Zisman, Saito, Berthelot and Owens-Wendt methods. It was shown that NaOH solution treatment increases roughness, polarity and surface free energy of polymers. As a result, T-Peel strengths for modified Mylar™ and Teonex™ films were respectively 2.2 and 1.8 times higher than that for the unmodified films, whereas AryLite™ adhesion test failed.

On the Evaluation of the Acidity and Basicity Parameters of the Surface Free Energy of Polymers

Polymeric surfaces of polyvinylchloride and polymethylmethacrylate were found to be unsuitable when considered to be monopolar. The acid-base properties of these polymers were studied by using the Berger method, and their composition was analyzed by IR-spectroscopy and quantum chemical analysis. In order to determine the acidity and basicity parameters of the surface free energy (SFE) of smooth solid surfaces, the three-dimentional graphical method was proposed based on nonlinear Della Volpe modification of the van Oss-Chaudhury-Good equation.

The influence of processing in discharge with a closed drift of electrons on the adhesion properties and the strength of polymer adhesive joints

Results obtained in studying the influence of processing in gas-discharge plasma with a closed drift of electrons on the surface free energy of polymers (polyethylene terephthalate, polyvinylidene fluoride, polysulfone, and polyimide) and the strength of adhesive joints formed by polymer materials and adhesion of paint-and-lacquer coatings.

A new approach to determination of the acid and base parameters of the surface free energy of polymers

A new approach to determination of the acid and base parameters of the surface free energy of polymers

Crystalline/Crystalline Phase Transitions in Polymer Systems Consisting of Finite-Size Crystals in Each Crystalline Phase: Generalized Gibbs-Thomson Equation

For polymer systems of two crystalline phases of one polymer component, each phase being consisted of polymer crystals of a finite size, we derive the crystalline-crystalline phase transition relationship, i.e., generalized Gibbs-Thomson equation. Its application combined with the crystalline-liquid transition relationship (usual Gibbs-Thomson equation) to the phase behavior of PT phase diagram of polyethylene (PE) is investigated, where the orthorhombic-hexagonal phase transition of PE crystal under high pressure being involved. Comparison with experimental data leads to the estimates of the structural characteristics such as the ratios of (the end surface free energy of polymer crystal/crystal length) for the respective crystalline phases.

Effect of different solid matrixes on surface free energy of EGDMA and TRIM polymers

Advancing and receding contact angles of water, formamide, glycerol and diiodometane were measured on the two polymers; EGDMA (dimethacrylate of ethylene glycol) and TRIM (trimethacrylate-1,1,1-trihydroksymethylopropane) which were polymerized next to glass, silanized glass, stainless steel, mica and silicon surfaces as the matrices. Then from the contact angle hystereses (CAH) and van Oss, Good, Chaudhury (LWAB) approaches the apparent surface free energies were evaluated. The measured contact angles not only depend solely on the polymer chemical structure but also, to some extent, on the solid matrix next to whose surface the sample has polymerized. Surface free energy of the polymer samples calculated from the LWAB approach shows that they interact mainly by dispersive forces. The apparent surface free energy of the polymers calculated from the diiodomethane contact angles hysteresis is practically the same irrespective of the kind of the matrix used. Therefore it can be concluded that the observed weak polar interactions in the surface free energy of the samples depend on the polymer surface preparation. The AFM images show that the obtained surfaces are of different roughness. The RMS values of roughness range between 3.7–90.2 nm for EDGMA, and 5.3–124.5 nm for TRIM. However, as reported in literature, rather protrusions bigger than 1 μm may significantly affect the contact angles, especially the receding ones.

Surface characterization of poly(methyl methacrylate-co- n-butyl acrylate-co-cyclopentylstyryl-polyhedral oligomeric silsesquioxane) by inverse gas chromatography

The surface properties of poly(methyl methacrylate-co- n-butyl acrylate-co-cyclopentylstyryl polyhedral oligomeric silsesquioxane) (poly(MMA-co-BA-co-styryl-POSS)) were studied by means of inverse gas chromatography (IGC) using 10 non-polar and polar solvents as the probes. Thermodynamic parameters of adsorption, e.g., specific retention volume, the dispersive component of the surface free energy, the specific interaction contribution to the free energy of adsorption and the acid/base constants were obtained to investigate the interactions between the surfaces of the copolymers and different solvents. It was found that incorporation of styryl-POSS into polymer resulted in increasing interactions between polymers and solvents, dispersive component of surface free energy of polymer and acidity of the surfaces of the polymers. The more the styryl-POSS were embedded, the stronger the interaction between the polymer surface and solvent, the dispersive component of the surface free energy and the acidity of the polymer surface were.

The recovery of plastics from waste with reference to froth flotation

Some authors have overstated the problem of plastics wastes accumulating in large quantities. The amounts and types of such wastes must be well understood if recovery methods, such as froth flotation, are to be applied successfully. Not all plastics discards are reasonably recoverable and statistics on gross quantities must be analyzed for those that are. The amount of plastic wastes generated can be related to plastics production only with an understanding of the product life spans of different plastics items and which plastics are used for items that will at some time be in the waste stream. Without this knowledge, feedstocks for recovery cannot be intelligently or economically chosen. Selected plastics mixtures have been separated by froth flotation for subsequent recovery of the individual plastics, reviewed here from the perspective of gamma flotation, float–sink based on the plastic surfaces’ values of the Zisman critical surface tension for wetting ( γ C). It is shown how float–sink may depend on the values γ C and the liquid surface tension ( γ L/G) of the flotation bath. Other investigators have reported flotation depression by the addition of selected water-soluble polymers and attribute the results to adsorption of these polymers on the plastics’ surfaces. Some authors attribute the effects of surfactants similarly to adsorption. This discussion questions these interpretations given the low surface free energy of polymers. The review and discussion is not intended to explain all observations by gamma flotation. It is intended to encourage new paths for additional research. Perhaps in spite of the gaps in understanding, there have been successful froth flotation separations of plastics, including separating a mixture of rigid plastics pieces recovered from municipal solid waste (MSW). Some previously unreported results of such experiments are summarized here.

Activation of polyethylene and polypropylene in atmospheric pressure glow discharge

The atmospheric pressure glow discharge was used for activation of polymer materials. The discharge was generated between two plane metal electrodes covered by a glass dielectric barrier. The discharge was ignited in pure nitrogen or in mixtures of nitrogen with hydrogen or nitrogen with ammonia. Studied polymers were polyethylene and polypropylene. The surface energy of both activated and non-activated polymers was determined by means of contact angle measurements. The influence of treatment time on the surface free energy of polymers was studied.

Temperature-induced phase transition at the polymer–water interface

Temperature-induced phase transition of polymer shows the bulk swelling change in the polymer network, which may induce the change of polymer surface properties. The contact angle measurements at the polymer–water interface were performed to observe the temperature-induced phase transition at the polymer–water interface using two-liquid technique. The dispersive and nondispersive components of surface free energy of polymer were measured above or below the phase transition temperature (lower critical solution temperature). A semi-interpenetrating polymer networks composed of sodium alginate and poly( N, N-dimethylaminoethyl methacrylate-co-ethyl acrylamide) were used as a model polymer system.

Surface chemistry and adhesion

Abstract Adhesion science is still a controversial area of research; no universal theory of adhesion exists and the actual mechanism of adhesion operating across many industrially important interfaces is still unresolved. In this review wetting processes and methods for estimating the surface free energy of polymers from contact-angle measurements are discussed. Emphasis is placed on the relationship between the work of adhesion estimated from surface free energies of solids and the measured adhesive joint strength.

Wear of lubricated plastics-based precision pivot bearings and the effect of the surface free energy of polymers

The effect of oil spreading on plastic bushes on the wear of steel-polymer precision pivot bearings was investigated. Analysis of oil spreading allowed a comparative evaluation of the surface free energy of the various polymers used as bush materials to be made. Correlation was found between the influence of lubrication on the wear of the bearings and the spreading velocity of the oil.

Surface tension and surface free energy of polymers

The curent state of problems connected with the definition and experimental determination of surface free energy and surface tension of polymers is discussed. An analysis of the application of some equations based on classical and modern thermodynamics of polymer solutions shows that present theories need an essential improvement to fit experimental data. The Zisman concept of critical surface tension and Fowkers' hypothesis of additivity in the contribution of polar and dispersion forces to surface tension are criticized and a new approach to the problem is proposed.