An atmospheric-pressure plasma jet (APPJ)-based surface treatment process was investigated for the structural (τB > 15 MPa) adhesive bonding of polyamide 6 (PA6) composites. The treated surfaces were examined by contact angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM). Additionally, the shear strengths of single lap specimens were determined as a function of different plasma intensities and polyurethane adhesives. Our results show that APPJ leads to an increase of the surface free energy, oxygen concentration, and number of functional groups. Furthermore, the topography of the surface was significantly modified by exposure to APPJ. AFM measurements show that special attention has to be paid to the intensity of the plasma treatment to avoid melting and flattening of the PA6 surface on the nanometer scale. With optimized multiple APPJ treatments, lap shear strength of 20 MPa was achieved for the first time for this material system, allowing the material system to be employed in future automobile applications.

Advancing and receding contact angle measurements on polymer surfaces can be performed using a number of different methods. Ballistic deposition is a new method for both rapidly and accurately measuring the receding contact angle of water. In the ballistic deposition method, a pulsed stream of 0.15-μL water droplets is impinged upon a surface. The water spreads across the surface and then coalesces into a single 1.8-μL drop. High-speed video imaging shows that, on most surfaces, the water retracts from previously wetted material, thereby forming receding contact angles that agree with the receding angles measured by the Wilhelmy plate technique. The ballistic deposition method measures the receding angle within one second after the water first contacts the surface. This rapid measurement enables the investigation of polymer surface properties that are not easily probed by other wettability measurement methods. For example, meaningful contact angles of water can be obtained on the water-soluble low-molecular-weight oxidized materials (LMWOM) formed by the corona and flame treatment of polypropylene (PP) films. Use of the ballistic deposition method allows for a characterization of the wetting properties and an estimation of the surface energy components of LMWOM itself. Both corona- and flame-generated LMWOM have significant contact angle hysteresis, almost all of which is accounted for by the non-dispersive (polar) component of the surface rather than by the dispersive component. Surface heterogeneity is thus associated primarily with the oxidized functionalities added to the PP by the corona and flame treatments.

The measurements of the contact angle of the aqueous solutions of TX-100 and TX-165 mixture with propanol on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA) were carried out. On the basis of the obtained results, the dependence between the cosine of contact angle and surface tension as well as between the adhesion and surface tension of the solutions in the light of the work of adhesion of the solutions to the PTFE and PMMA surface was discussed. The dependence between the adhesion and surface tension for PMMA was correlated to the surface concentration of propanol as well as TX-100 and TX-165 mixture concentration determined from the Frumkin equation at the PMMA-air, PMMA-solution and solution–air interfaces. For this purpose, the surface tension of PMMA covered by a surface active agent film was determined using the Neumann et al. equation and next the PMMA–solution interface tension was evaluated from the Young equation. The values of the surface tension of PMMA covered by propanol and surfactants mixture layer were applied to describe the changes of the adhesion work of solutions to PMMA surface as a function of propanol and surfactants mixture concentration. The adhesion work of the aqueous solutions of TX-100 and TX-165 mixture with propanol to the PTFE and PMMA surfaces was discussed in the light of the adhesion work of particular components of the solutions. On the basis of the results obtained from the contact angle measurements, the standard Gibbs free energy of adsorption of particular components of solution was also considered.

A wide variety of plasma treatments was performed on polyethylene surfaces, resulting in a wide range of total surface energies. The linear correlation of with cos θ was discussed in light of the Young–Dupré equation. Hundred percent of the surface energy variation was accounted for by the polar component of surface energy; the dispersive component was not affected by surface treatment. These data show that for this polymer the contact angle of a single polar liquid can be used as a robust quantitative indicator of treatment level, and because of its excellent linear correlation with total surface energy for this system, can be used as a quantitative measure of total surface energy.

In this study, a surface modification of the poly (ethylene terephthalate) (PET) film using TiO₂ photocatalytic treatment was investigated. In order to enhance the adhesion strength between the PET film and the electroless copper film, the effects of TiO₂ crystal forms, TiO₂ particle sizes, and TiO₂ content, as well as treatment condition, upon the surface contact angle, surface characterization, and adhesion strength were investigated. Anatase TiO₂ with a particle size of 5 nm had a high catalytic activity and dispersibility in aqueous solution. After the optimal photocatalytic treatment, the surface contact angle of the PET film decreased from 84.4° to 19.8°, and the surface roughness of the PET film increased from 36 to 117 nm. The adhesion strength between the PET film and the electroless copper film reached 0.89 KN m⁻¹. X-ray photoelectron spectroscopy analyses indicated the carbonyl group was formed on the PET surface after photocatalytic treatment, and the surface hydrophilicity was improved. Consequently, TiO₂ photocatalytic treatment is an environmentally friendly and effective method for the surface modification of the PET film.

Polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) films were treated with an atmospheric-pressure plasma (APP) jet and a 172-nm ultraviolet (UV) excimer light in air. The advancing and receding water contact angles on both films decreased after the treatments, especially after APP treatment. After the treatments, the hydrophobic recovery was observed and almost diminished within a week. The dispersive component of the surface free energy of the two polyester films did not change due to the APP and UV exposure, whereas the acid–base component drastically increased after the treatments. The X-ray photoelectron spectroscopy results showed that the polyester film surfaces were oxidized by the treatments. From the AFM images, the topographical change on the film surfaces due to the treatments was clearly observed. It was found that the APP treatment of the PET film prevented the deposition of particulate soils in air due to the decrease in the contact area between the film and the soil particle. Furthermore, the soil release in the aqueous solutions was promoted as a result of the hydrophilization of the polyester films due to the APP treatment.

This paper reports on a special pilot coating and industrial printing trial designed to gain fundamental knowledge on ink adhesion failure on coated papers. We found that ink adhesion failure resulted in white spots without ink on the paper, referred to as uncovered areas and these spots gave print mottle problems. The white spots were due to two fundamentally different types of ink adhesion failure. One is the well-known ink rejection, which simply means that ink is not transferred to the surface. The other is a new type of ink adhesion failure, confirming a previous hypothesis suggested from laboratory observations. We refer to this as ink-lift-off adhesion failure, meaning that ink initially deposited on the paper surface becomes lifted off from the surface in a subsequent print unit. Adhesion failure by this mechanism was seen to occur more frequently than failure due to the well-known ink rejection.

This paper studies the effects on valid domain of contact angles and error limits of solid surface tension components and parameters (SSTCPs)/square roots of SSTCPs (SQSSTCPs) from the changes in liquid surface tension components and parameters (LSTCPs) when applying the van Oss–Chaudhury–Good (vOCG) approach. The results of maximum absolute errors and maximum relative errors (MREs) in SQSSTCPs/SSTCPs, induced by errors in LSTCPs or contact angles, show that most SQSSTCPs/SSTCPs can be evaluated at moderate accuracy from the lowest condition number liquid triplets, assuming that |Δθ_i| = 1° and  = 0.1 mN/m (i = 1, 2, 3, k = LW, +, −). This confirms the validity of the vOCG approach. The accuracy of each SQSSTSCP/SSTCP declines with increasing θ_i or decreasing parameter when θ_i > 0 or a critical value, provided the other two contact angles are kept fixed. This explains the underlying reasons for negative SQSSTCPs. At the scale proposed by vOCG, dimethyl sulphoxide is not suggested for use. Comparing with the MREs obtained at vOCG scale, considering the acidity of diiodomethane improves the accuracy of ; using the scales proposed by Lee and Shen do not affect the accuracy of SSTCPs, but using the scale proposed by Della Volpe et al. improves the accuracy of SSTCPs at low θ₂ and θ₃ while declines that at high ones. For a low , low surface tension apolar liquid is preferred for high accuracy. The dependence of the accuracy of SQSSTCPs/SSTCPs on contact angles suggests the importance of considering contact angle in accuracy evaluation.

The optimization of heat-sealing process parameters, including time, temperature, and pressure, was performed on a monolayer linear low-density polyethylene (LLDPE) film. The seal properties examined for each process condition were: seal initiation temperature (T_si), plateau initiation temperature (T_pi), final plateau temperature (T_pf), plateau seal strength (SS_p), and failure mode. Increasing dwell time enhanced seal strength. However, it was found that the rate of this enhancement is different for each interval of dwell time. A narrow temperature plateau was observed for dwell times lower than 0.4 s and higher than 2 s, while in between a broad temperature window was observed. The pressure shows its influence up to the stage of wetting. And after providing the intimate contact between two film layers, additional increase in pressure does not enhance seal strength significantly. A 3D mapping of process safety zone was introduced for seal strength in the range of heat seal process variables for the very first time. The analysis of this 3D representation revealed that seal strength has a linear correlation with the square root of dwell time. In addition, the interfacial bond strength was shown to be proportional to the fraction of melted crystals. It was found that this fraction is determined by dwell time and temperature. Topography and morphology of surfaces after peeling revealed enlargement of fibrillar morphology to taller failure fracture complex shapes. Extensive roughness analysis on film surfaces after peeling found the much rougher surfaces after breakage of strong bonding.

Polydimethylsiloxane (PDMS) and glass are among the most widely used materials in biomedical and microfluidic applications. In this paper, oxygen plasma exposure was used to improve the adhesion properties of PDMS and glass. The effect of bonding quality parameters such as RF power, time of activation and oxygen flow was investigated. Bonding area and strength, two main indicators of bonding quality, were detected using manual peel and mechanical shear tests, respectively, to optimize the bonding parameters. It was observed that increase in activation time and RF power increased the bonding strength considerably. The oxygen flow had a slight influence in increasing the bonding strength. The application of this bond has also been demonstrated in PDMS–glass micropump, so this technique can be potentially applied for fabrication of PDMS–glass-based microfluidic and biomedical devices.

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.

The surface energy parameters of polycaprolactone (PCL) were determined at 160 and 180°C from its interfacial tensions with probe polymers. The probe polymers were polystyrene (PS) and poly(methyl methacrylate) (PMMA). This method is based on the well-known relationship between blend interfacial tension and polymer surface energy parameters, and requires the use of at least two probe polymers, whose surface energy parameters at the temperature of interest have been independently determined. It also requires direct measurement of blend interfacial tension at the high temperatures of interest. The interfacial tensions were obtained from direct measurements by the imbedded fiber retraction method. The following results were obtained: (a) γ^P (polar component) values for PCL was within the range reported using other methods, (b) γ^D (dispersion component) values for PCL decreased with increasing temperature, consistent with expectations and (c) γ^D values for PCL were on the high end, but still within the rather broad range of reported values.

During the past decade polylactide acid (PLA) polymer has been the subject of numerous researches aimed at comparing it with traditional petroleum based polymers for many packaging applications. PLA is biodegradable and derived from agricultural by-products such as corn starch or other starch-rich substances like maize, sugar or wheat.While PLA is currently being used in many packaging applications with well documented performance, little work has been done comparing printing processes and performance. This study presents PLA printing performance and sustainability findings using the common flexography printing process. Various analytical methods were used to evaluate performance and provide recommendations for optimized printing on PLA as compared to PET, oriented PP and oriented PS. Results of this study found that PLA films were comparable in printability and runnability to standard petroleum based flexible packaging films.

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.