Polyethylene (PE) is often used in several industrial applications including the building, packaging and transport industries. Aluminum (Al) is widely used in different applications in the automotive, railway, aeronautic, and naval industries because of its excellent mechanical and chemical properties. Laminates prepared from Al and PE lead to an enhancement in physical and mechanical properties. These materials play a main role in the packaging and building sectors, such as in TetraPak containers and aluminum composite panels. The main problem observed is associated with the adhesion between polymers and metals. This research focused on investigating the enhancement in the adhesion of the PE/Al laminate using the corona discharge. The corona treatment of the surfaces led to a significant increase in the adhesion of the PE/Al laminate as a result of improved surface properties confirmed by peel test measurements. Moreover, the positive effect of the corona treatment in combination with a primer on the improvement of adhesion characteristics was observed too. Different analytical techniques were employed to characterize the effect of the corona treatment on the improvement in adhesion of PE/Al. A significant increase in wettability was confirmed by the measurement of contact angles. Changes in the surface morphology of the PE and Al surface, after the corona treatments at different operating conditions, were observed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to analyze changes in chemical composition after the corona discharge effect on PE and Al surfaces.

Atmospheric pressure plasma treatment of the surface of a polypropylene film can significantly increase its surface energy and, thereby improve the printability of the film. A laboratory-scale dielectric barrier discharge (DBD) system has therefore been developed, which simulates the electrode configuration and reel-to-reel web transport mechanism used in a typical industrial-scale system. By treating the polypropylene in a nitrogen discharge, we have shown that the water contact angle could be reduced by as much as 40° compared to the untreated film, corresponding to an increase in surface energy of 14 mNm⁻¹. Ink pull-off tests showed that the DBD plasma treatment resulted in excellent adhesion of solvent-based inks to the polypropylene film.

In this paper, a polymeric coating based on the modified chlorinated polypropylene (CPP) emulsion was synthesized, methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA) were grafted onto CPP backbone and phase inversion was conducted to obtain waterborne emulsion. Results showed that the concentration of initiator (BPO) had the greatest effect on graft copolymerization. The concentration of emulsifier and temperature influenced the results of phase inversion. Besides, the thermal performances of modified CPP were better than untreated one. In addition, the coating obtained in optimum condition had excellent adhesion to BOPP film, and apparently improved the printing quality of the film. The printability promotion should be attributed to the different movement trend of coating’s polar and un-polar chains during the baking step, as well as the subsequent formations of new coating/substrate and coating/ink interface layer.

This paper, as the title underlines, will be focused on flame treatment technology applications, mainly on BOPP substrates.

After an introduction regarding flame chemistry and BOPP surface activation mechanisms, this paper will be focused on unique flame treatment oxidation performances, in comparison with other treatment methods actually used in the market.

Focus will then be moved to the characteristics and advantages of using flame treatment for film surface treatment. In particular, a comparison will be run with other surface treatment technologies (corona surface treatment and atmospheric plasma treatment) in terms of:

• q surface energy after treatment;
• surface oxidation mechanisms and chemical species involved;
• quantity of oxygen on treated surface (oxidation level);
• quality of oxygen on treated surface;
• adhesion;
• printability/print quality.

Typical and new applications of flame treatment will be presented, underlining benefits coming from flame usage for pretreating different types of skins. Finally, the paper will try to make rid of prejudices and misinformation concerning flame treatment process applications, especially to certain kind of webs and substrates.

Polymers/metal laminates are often used to improve physical and mechanical properties, especially those required in building applications. A flat aluminum composite panel (ACP) consisted mainly of two thin metal sheets usually made of aluminum (Al) and a non-metal core, such as polyethylene (PE). The lack of adhesion associated with the low wettability of PE is a serious problem. An eco-friendly, dry, non-destructive corona treatment technique can be applied to solve this problem. In this work, the use of a corona treatment to enhance the adhesion properties of linear low-density polyethylene (LLDPE) was studied. The changes in surface and adhesion properties were thoroughly analyzed using various analytical techniques and methods to obtain the optimal parameters for corona discharge using contact angle measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM force adhesion measurements were used to analyze the effect of the corona treatment on the adhesion enhancement of LLDPE, and the peel tests confirmed a significant increase in peel resistance in the LLDPE/Al laminate. A synergy effect from using the corona treatment in combination with an ethylene acrylic acid dispersion primer was observed.

The aim of this study was to analyze how corona dosages above recommended levels affect film surface energy and hydrophobic recovery of such treated film surfaces as well as laminate bond strength of laminates made of these films. The adhesive for lamination was a polyurethane-adhesive with a dry film thickness of ∼5 µm. Polar and dispersive parts of the surface energy were measured frequently according to DIN 55660-2 (Owens–Wendt–Rabel-and-Kaelble method) for up to 140 days after corona treatment. The corona dosage had a value of up to 280 W min/m². Laminate bond strength was measured according to DIN 55543-5. The effect of corona treatment was highest for low-density polyethylene (PE-LD) films, mean for biaxial-oriented polypropylene (PP-BO) films, and lowest for biaxial-oriented poly(ethylene terephthalate) (PET-BO) films. With increasing storage time, surface energy decreased, as expected. The higher the effect of corona treatment, the faster the polar part of surface energy decreased. At PE-LD, laminate bond strength increased with a higher corona dosage from 0.05 to 8.87 mN/15 mm, whereas at PET-BO and PP-BO laminate bond strength was so high that samples teared before delamination during bond strength testing. By our results is shown that corona dosages above recommended levels resulted in higher laminate bond strength. Only at PP-BO a reduction of laminate bond strength due to “overtreatment” was be observed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45842. https://onlinelibrary.wiley.com/doi/abs/10.1002/app.45842

Polar and dispersion surface free energy (SFE) can be determined with the Owens-Wendt method. Thereby, contact angles (CAs) of at least two liquids with known surface tension (ST) components are measured. The ST components can either be determined through experiment or drawn from literature. However, it is important to know how big the difference is between SFE component values that have been calculated with experimentally-determined ST values or values derived from literature. In this study, STs of different test liquids were analyzed by Pendant Drop method and the components by CA measurement on a non-polar surface. CAs on different polymer surfaces were measured to calculate SFE components with the Owens-Wendt method. The calculations conducted were either based on experimentally-determined ST parts or different sets of values found in the literature. The findings of the survey show that, depending on the set of literature values used, the SFE results deviate significantly from the values obtained from experiment. Expressing this deviation in figures, in extreme cases the polar part differs for some polymers by -100% to +100%, with the dispersion component spanning -50% to +43%. In comparison, the expected relative uncertainties exhibited by the experimentally-determined ST values are about 15% for the polar and approximately 5% for the dispersion SFE part. Hence, the results show that the SFE uncertainty can be reduced significantly by means of analyzing the ST parts experimentally.

Wetting, the process of water interacting with a surface, is critical in our everyday lives and in many biological and technological systems. The contact angle is the angle at the interface where water, air and solid meet, and its value is a measure of how likely the surface is to be wetted by the water. Low contact-angle values demonstrate a tendency of the water to spread and adhere to the surface, whereas high contact-angle values show the surface’s tendency to repel water. The most common method for surface-wetting characterization is sessile-drop goniometry, due to its simplicity. The method determines the contact angle from the shape of the droplet and can be applied to a wide variety of materials, from biological surfaces to polymers, metals, ceramics, minerals and so on. The apparent simplicity of the method is misleading, however, and obtaining meaningful results requires minimization of random and systematic errors. This article provides a protocol for performing reliable and reproducible measurements of the advancing contact angle (ACA) and the receding contact angle (RCA) by slowly increasing and reducing the volume of a probe drop, respectively. One pair of ACA and RCA measurements takes ~15–20 min to complete, whereas the whole protocol with repeat measurements may take ~1–2 h. This protocol focuses on using water as a probe liquid, and advice is given on how it can be modified for the use of other probe liquids.