Surface Properties Of Polyethylene Research Articles

Polyethylene Film Surface Modification via Benzoic Acid Grafting.

A polyethylene (PE) film surface modification method is proposed via benzoic acid (BA) alkylation grafting to improve the surface affinity to polar substances. The procedure involves sequentially spraying AlCl3 and BA onto the heat-softened PE surface. The occurrence of the alkylation reaction was evaluated through comparative chemical, morphological, and thermal analyses. It was demonstrated that the grafting reaction of BA onto the PE film surface took place, limited to the surface layer, while preserving the bulk properties of PE. The reaction resulted in the formation of aluminum benzoate complexes, which improved the surface affinity to polar compounds. The impact of grafting on the surface properties of PE was further assessed by comparing the behavior of PE films treated with BA and untreated PE films when painted with watercolors. The PE film grafted with BA exhibited increased affinity towards watercolors, providing strong evidence of a change in surface polarity from hydrophobic to hydrophilic. These findings indicate that the proposed methodology effectively renders the PE surface paintable, even with non-toxic water-based inks, making it suitable for applications such as packaging.

The impact of particle size and photoaging on the leaching of phthalates from plastic waste

Plastic wastes are important sources of phthalates (PAEs), which are a class of endocrine disrupting compounds (EDCs). However, there are still knowledge gap about how environmental weathering processes affect the release of PAEs from plastics wastes. In this study, we investigated the effects of particle size and photoaging on the leaching of PAEs from two kinds of commercial polyethylene plastic express packaging bags with different PAEs contents. Reduction of the size of the plastic from 5 cm to <0.5 mm did not significantly change the leaching of PAEs from the express packaging bags. After photoaging, the sum of all detected PAEs (∑PAEs) leaching amounts from two plastic bags were 1.76–2.91 times and 1.24–2.19 times higher than those of the two original materials, respectively. However, due to the degradation effect of ultraviolet (UV) irradiation on PAEs in plastics, the leaching amount of PAEs decreased at the later stage of the photoaging. The effect of photoaging on the surface properties of polyethylene (PE) plastics, especially on the surface functional groups and hydrophilicity, contributed significantly to the leaching of PAEs. The result of this study indicated that the risk of PAEs release from plastic wastes in the environment could be promoted by photoaging processes. Considering the high leaching ratios of PAEs from plastic packaging materials in this study, these plastic bags may increase the environmental burden and risk of PAEs, even though the PAEs levels of them are low.

Effect of Accelerated Protons on the Surface Properties of Polyethylene

The irradiation of low-density polyethylene with MeV protons leads to a substantial increase in surface free energy, its acid–base component, and surface polarity due to the appearance of functional groups in the surface layer, as confirmed by ATR IR and Raman spectra. It has been shown that the surface energy of the irradiated polymer depends little on the change in proton energy from 1 to 4 MeV at a fluence of 1015 proton/cm2. It has been found that the oxygen content of the irradiated polymer surface increases as a result of oxidative reactions of the radicals generated during radiolysis and the thermal stability of the polymer decreases.

Surface modification of polyethylene in an argon atmospheric pressure plasma jet

The surface properties of polyethylene can successfully be altered using argon plasmas. In this work, the surface modification of low density polyethylene (LDPE) using an argon atmospheric pressure plasma jet (APPJ) is profoundly investigated. The surface modification is examined using different analysing techniques namely, water contact angle (WCA) measurements for the wettability and X-ray photoelectron spectroscopy (XPS) for the chemical composition. Particular attention is paid to the treatment distance between the plasma jet capillary and the LDPE foil and the applied treatment time. At treatment distances between 5 and 15mm, the WCA can be reduced with more than 70% within a treatment time of a few ms. XPS measurements reveal that this is due to the incorporation of oxygen containing groups and especially the increased implementation of the O–CO group has a big influence. At treatment distances above 15mm, the wettability decreases with increasing treatment distance. The wettability can however be enhanced by increasing the treatment time. Ageing considerations show that the loss in treatment efficiency is restricted to only 25%, meaning that even after 14days of ageing the WCA reduction upon plasma treatment is still more than 40%. Based on the above mentioned results, the most appropriate parameters can thus be selected to provide an efficient plasma treatment of LDPE using the argon APPJ.

Low Pressure DC Glow Discharge Air Plasma Surface Treatment of Polyethylene (PE) Film for Improvement of Adhesive Properties

The present work deals with the change in surface properties of polyethylene (PE) film using DC low pressure glow discharge air plasma and makes it useful for technical applications. The change in hydrophilicity of the modified PE film surface was investigated by measuring contact angle and surface energy as a function of exposure time. Changes in the morphological and chemical composition of PE films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap-shear strength. The results show that the wettability and surface energy of the PE film has been improved due to the introduction of oxygen-containing polar groups and an increase in surface roughness. The XPS result clearly shows the increase in concentration of oxygen content and the formation of polar groups on the polymer surface. The AFM observation on PE film shows that the roughness of the surface increased due to plasma treatment. The above morphological and chemical changes enhanced the adhesive properties of the PE film surfaces, which was confirmed by T-peel and lap-shear tests.

Surface oxidation of polyethylene using an atmospheric pressure glow discharge with liquid electrolyte cathode

This study investigated the action of an atmospheric pressure air glow discharge (APGD) with aqueous electrolyte cathode onto the surface of polyethylene (PE) films. Distilled water and aqueous solutions of KCl and HCl were utilized as a cathode. The surface properties of PE were characterized by contact angle measurement followed by surface free energy calculation, Fourier transform infrared by attenuated total reflectance (FTIR-ATR), and XPS. After treating the PE surface, we observed OH groups, C O groups in ester, ketone, and carboxyl groups, and C O groups in unsaturated ketones and aldehydes. For a treatment time of 20 min and a discharge current of 40 mA, atomic concentrations of O and N were 12% and 2%, respectively, under distilled water application. Modification processes were able to improve the surface free energy of PE.

Surface properties of polyethylene after low-temperature plasma treatment

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

Study of Cobalt Sorption on Polyethylene

The results gained from the study of cobalt accumulation on polyethylene are presented in this paper. To clarify the role of colloid formation, the presence of borate species, and the surface properties of polyethylene in accumulation process, several independent techniques such as the in situ radiotracer method, centrifugation, FTIR, and Raman spectroscopy are used. From the results, it can be stated that the kinetics of cobalt accumulation is dependent on the pH and composition of the solution phase. The accumulation of cobalt proceeds in both colloid and ionic forms; however, the amount of sorbed ionic cobalt species increases with pH due to their accumulation on colloids. The lower cobalt accumulation in borate-containing solution is attributed to the lower amount of colloid formation.

Surface properties of polyethylene grafted with triallyl cyanurate in the presence of an electron beam

The surface energy and thermodynamic work of adhesion of polyethylene grafted with triallyl cyanurate in the presence of an electron beam have been determined. The surface energy increased with the grafting level and with the irradiation dose up to 10 Mrad. A similar trend was observed with the work of adhesion. The changes in these surface properties were correlated with the concentration of the polar groups as measured by IR (infrared) spectroscopy and ESCA (electron spectroscopy for chemical analysis) studies.

A comparative study of the effects of remote nitrogen plasma, remote oxygen plasma, and corona discharge treatments on the surface properties of polyethylene

The effects of remote nitrogen plasma, remote oxygen plasma, and corona discharge treatments on linear low-density polyethylene were studied with regard to the chemical and physical surface modification, depth of modification, and surface stability. An attempt was made to correlate the type and the extent of modification with the printing and adhesion properties of the modified surfaces. Surface topography was studied using scanning electron microscopy. The relative percentages of nitrogen and oxygen on the surfaces were determined by X-ray photoelectron spectroscopy. Printing and adhesion tests were performed using standard, commercially available inks and adhesives.

Surface properties of polyethylene: Effect of an amphipathic additive

Previous studies have shown that small amounts of amphipathic (i.e., polar non-polar) molecules, in particular oleamide, cause a marked lowering of the coefficient of friction between thin films of polyethylene. In this paper the surface chemical properties of the aging film and the nascent film (i.e., during the flat film extrusion process) have been studied. The wettability (contact angle) and friction of the aging film at room temperature show that the friction is reduced only when sufficient additive is present to form a weakly held monomolecular layer. This monolayer is formed by almost complete exudation of the additive from the bulk. Contact angle measurements show that the molecules become oriented on the surface such that the polar groups are in contact with the polyethylene and the hydrocarbon chains project into the air. The stability of the monolayer to water condensation is much improved by flame treatment of the film immediately on extrusion. On preparing film by extrusion through a water-quenching bath it has been found that water adheres more easily to films containing oleamide. By suitable adjustments, the water bath was modified to form a “dynamic” Langmuir trough. Contact angle measurements on the emerging film and studies on the effect of sweeping the water surface around the emerging film show that the surface tension of the water is lowered by the amphipathic molecule being quantitatively stripped off the film as it emerges through the water/air interface. From surface pressure/area relationships, the surface concentrations of the spreading molecules are calculated. It is found that there is a surface concentration about one hundred times greater than would be expected from a uniform distribution of the additive throughout the polymer. This large surface excess is approximately proportional to the bulk concentration and implies a pronounced adsorption at the polymer melt/metal or polymer melt/air interface.