The use of gas and/or liquid-phase carbon dioxide (CO2) with atmospheric plasma discharge surface pretreatment technology can remove micron and submicron particulates and hydrocarbon-based contaminations on plastics and metals. The cleaning process is based upon the expansion of either liquid or gaseous carbon dioxide through an orifice. The paper provides an understanding of the basic removal mechanism and provides experimental evidence of remarkable adhesion improvements relative to a broad range of applications in electrical, medical, and automotive manufacturing communities.

RFID research and development requires technical expertise of ink and adhesive manufacturers, surface treatment and printing equipment manufacturers, package printers, and electronics firms. In this framework, a strong enhancement in production and quality can be obtained with surface substrate treatments. Here we will discuss the state-of-art in RFID production and the advantages that a plasma treatment of the substrate can give to RFID label printing.

A recent study has illustrated a sizeable increase in the printing characteristics of nonwovens following atmospheric plasma treatments. The improvement of properties such as wettability, printability and adhesion opens up new application prospects for treated fabrics.

Extrusion coating, lamination and film lamination give rise to complex manufacturing techniques which allow a converter to make high-performance packaging films. The physical properties and the related performance characteristics of composites obtained by extrusion coating and lamination can be comparable to that produced by film lamination. This is not surprising since many of the major components involved by these techniques in the production of the final composites are also the same. The paper examines how the use of ozone combined with corona discharge compares to ozone combined with atmospheric plasma relative to seal strength for these composite film constructions, and suggests a direction for future improvements in seal strength.

There are many current and emerging wetting and adhesion issues which require an additional surface processing to enhance interfacial surface properties. Materials which are non-polar, such as polymers, have low surface energy and therefore typically require surface treatment to promote wetting of inks and coating. One way of increasing surface energy and reactivity is to bombard a polymer surface with atmospheric plasma. When the ionized gas is discharged on the polymer, effects of ablation, crosslinking and activation are produced on its surface. In this paper we will analyse the role of plasma and its use in increasing the surface energy to achieve wettability and improve adhesion of polymeric surfaces.

In this study, the adhesion properties of adhesives and paints on wood–plastic composites (WPCs) after plasma treatment at atmospheric pressure and ambient air were investigated. Surface energy determination by means of contact angle measurements according to the Owens–Wendt approach and atomic force microscopy to detect changes in surface topography were carried out. An increase in the polar component of surface energy and an increase in surface roughness after plasma treatment were detected, indicating enhanced bond strength. To confirm these results, bond strength tests were conducted. By tensile bond strength tests, increased adhesion of waterborne, solventborne and oil-based paints on plasma treated surfaces was found. Furthermore, by shear bond strength tests, an increase in bond strength of plasma treated WPCs bonded with poly(vinyl acetate) and polyurethane adhesives was ascertained.

Polyolefin plastomer films formulated with slip and antiblock were blown on a wide die gap with and without two Dynamar^™ polymer processing additives (PPAs). A wide die gap was used so that melt fracture-free film could be obtained with no PPA present for comparison purposes. The films were analyzed for the following properties: surface tension (on treated films), gloss, haze, clarity, transmittance, hot tack, heat seal, COF and block. In addition, the surface of films was examined using ESCA (Electron Spectroscopy for Chemical Analysis) and SSIMS (Static Secondary Ion Mass Spectrometry) to determine the surface chemical composition. PPAs when used at typical dose levels were shown to have essentially no effect on the surface and optical properties of plastomer films.

A superhydrophobic polyurethane-based film is described, on which the water advancing and receding contact angles are 150° and 82°, respectively. The film was prepared from surface-fluorinated polyurethane (PU), obtained from a well-defined fluorinated isocyanate, with silica particles incorporated within the film. In the absence of the silica particles, smooth fluorinated PU films with about 2 wt% fluorine demonstrate water advancing and receding contact angles of 110° and 63°, respectively. A major cause for the large contact angle hysteresis, similar to the so-called 'sticky' superhydrophobic behavior, on the roughened PU films is believed to originate from the surface reorganization of the fluorinated PU upon contact with water, which is characteristic for the partially fluorinated PU film. When a similar poly(dimethylsiloxane) (PDMS)-based roughened film was made, the water contact angle hysteresis could be reduced significantly, since the long PDMS chain can effectively suppress the surface reorganization upon contact with water.

Polypropylene (PP), low-density polyethylene (LDPE), and high-density polyethylene (HDPE) sheets were surface-modified by radio-frequency ammonia plasmas in order to improve the strength and durability of adhesive bonding, particularly under hot and humid conditions. Surface analyses by contact angle measurements, XPS (X-ray photoelectron spectroscopy), and FTIR-ATR (Fourier transform infraredattennuated total reflection) showed incorporation, upon plasma treatment, of both nitrogen- and oxygen-containing functional groups on the polyolefin surfaces, with similar surface compositions on modified LDPE and PP. Plasma-treated polyolefin samples bonded with a cyanoacrylate adhesive possessed a high shear bond strength in ‘dry’ conditions. On exposure to hot and humid conditions (immersion in 60°C water), the bond strength decreased with time in some cases while for other samples the lap shear strength was the same after exposure to the humid environment for 1 month compared with that under 'dry' conditions. Ammonia-plasma-treated HDPE specimens displayed the best strength retention upon water immersion. The excellent durability of the bond strength under humid conditions is indicative of covalent bonding between the cyanoacrylate adhesive and amine groups, which unlike physical bonding (e.g. van der Waals interactions) is not disrupted by the ingress of water molecules. It is also possible that the structure of the interphase is in the form of an interpenetrating network, obtained through penetration of the adhesive into the plasma-modified laycr, followed by covalent bonding and curing of the penetrated adhesive.

The paper proposes a modified Hildebrand-Scott equation to estimate the critical surface tension of polymers based on their molecular constitution.