Plasma surface treatment of plastics is definitely not new, nor is it commonplace. What is a plasma and what can it do is the subject of the following paper. A plasma is an excited gas, not unlike the aurora borealis. The excited particles that comprise the plasma bombard materials placed within their environment causing permanent change to their surface properties. By the judicious selection of process gas(es) and process parameters, the surface can be reengineered to fit specific needs. This paper presents quantitative analytical data on the chemical changes to the surface of polyethylene subjected to a plasma.

Many experiments have been performed globally to investigate ways of improving adhesion to polymers. This paper discusses current atmospheric surface activation systems, appropriate measurements of wettability and adhesion, over-treatment effects and surface analysis techniques relative to optimizing the adhesion of inks, paints, coatings and adhesives to polymer surfaces. Recommendations for improved activation by substrate and application are discussed.

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.

Surface activation of polymer films to modify surface properties is widely practiced to enhance wettability, printability and adhesion properties of these films. Sigma Technologies has been actively pursuing the area of longlasting activation of polymer films using various techniques including plasma technology. Atmospheric glow discharge plasma technology has been a recent addition towardsthese efforts. Plasma activation using a variety of precursors has been investigated for long lasting functionilization of various substrates. Latest developments in the area of surface activation of polymer films will be presented.

Plasma treatment is a common process for cleaning, etching and chemically functionalizing surfaces of polymer films. High speed plasma treatment is performed at atmospheric and subatmospheric pressure with a treatment device combining magnetic and hollow cathode effects, which enhance the gas ionization and focus and direct the plasma energy onto the surface of the moving web. Plasma treated polymer films show highly increased micro roughness. Polymer films metallized after plasma treatment exhibit highly improved adhesion between polymer and metal and better oxygen and water vapor barrier behaviour. Fabrics can be treated to attain hydrophilic or hydrophobic properties.

The measurement and interpretation of contact angles deceptively appear to be simple. This paper attempts to summarize the pitfalls in the field, and how to avoid them. First, the fundamental underlying theory that is necessary in order to properly measure and interpret contact angles is discussed, emphasizing recent developments. Then, the practical implications of these theoretical aspects are presented. In addition, the discussion highlights the missing pieces of the picture that need to be completed through future research.

This article attempts to give an overview of atmospheric plasma sources and their applications. The aim is to introduce, in a first part, the main scientific background concerning plasmas as well as the different atmospheric plasma sources (description, working principle). The second part focuses on the various applications of the atmospheric plasma technologies, mainly in the field of surface treatments.Thus this paper is meant for a broad audience: non-plasma-specialized readers will find basic information for an introduction to plasmas whereas plasma spectroscopists who are familiar with analytical plasmas may be interested in the synthesis of the different applications of the atmospheric pressure plasma sources.

Polyolefins such as polyethylene, polypropylene and their copolymers have excellent bulk physical/chemical properties, are inexpensive and easy to process. Yet they have not gained considerable importance as speciality materials due to their inert surface. Polyethylene in particular holds a unique status due to its excellent manufacturer- and user-friendly properties. Thus, special surface properties, which polyethylene does not possess, such as printability, hydrophilicity, roughness, lubricity, selective permeability and adhesion of micro-organisms, underscore the need for tailoring the surface of this valuable commodity polymer. The present article reviews some of the existing and emerging techniques of surface modification and characterisation of polyethylene. Surface modification of polymers, polyethylene in particular, has been extensively studied for decades using conventional tools. Although some of these techniques are still in use, they suffer from distinct shortcomings. During the last two decades, different means of surface modification have been thoroughly explored. The increasing expectancy for smart materials in daily life has, of late, sharply influenced research in the area of surface modification. Technologies that involve surface engineering to convert inexpensive materials into valuable finished goods have become even more important in the present scenario. In this review article we have attempted to broadly address almost all conventional and modern techniques for the surface modification of different physical forms and chemical compositions of polyethylene. This article will hopefully stimulate further research in this area and result in the development of polyolefins with multi-functional and responsive surfaces, which would ultimately lead to the commodities of polyolefins with smart surfaces.

As discussed in Chapter 1, it has been recognized for many years that the establishment of intimate molecular contact is a necessary, though sometimes insufficient, requirement for developing strong adhesive joints. This means that the adhesive, and primer if one is employed, needs to be able to spread over the solid surface, and needs to displace air and other contaminants that may be present on the surface.

The surfaces of five EUROBIOMAT standard biomaterials are characterized by contact angle measurements applying the sessile drop method using a goniometer. The advancing angles of ten liquids composed of formamide and ethyl CellosolveR according to ASTM D 2578-84 and aqua bidest. are measured. From these data, surface characteristics such as critical surface tension, surface free energy and dispersive surface tension are determined.

This chapter highlights a variety of techniques that are commonly used to measure contact angles, including the conventional telescope-goniometer method, the Wilhelmy balance method, and the more recently developed drop-shape analysis methods. The various applications and limitations of these techniques are described. Notably, studies of ultrasmall droplets on solid surfaces allow wetting theories to be tested down to the nanometer scale, bringing new insight to contact angle phenomena and wetting behavior.

Polypropylene (PP) films have been widely used in many industrial areas, such as for protective overcoats and food packaging. However, PP film’s hydrophobic surface properties induce poor wettability and adhesion; these properties have restrained the application of these films. Many surface modification techniques like wet-chemical treatment, UV irradiation, and plasma (including the atmospheric-pressure plasma, APP) treatment have been applied to films to enhance their hydrophilic properties. Among these technologies, APP treatment has attracted much attention due to its dry process, low vacuum equipment cost, and high productivity. In this study, the influence of process parameters would be the reactive gas ratio of plasma. To enhance its surface characteristics, treatment of PP film’s surface by APP was investigated. The XPS, OES, contact angle analyzer, SEM and AFM were used to examine the effect of process variables on film surface characteristics. It was found that Ar plasma mixing with oxygen has a better lasting aging effect. Moreover, the roughness of films is slightly changed after treatment. Through XPS analysis, we observed that the O/C ratio of PP decreases with an increased exposure time in air. Finally, the relationship among the aging time, surface energy, and roughness of the film was also investigated.

An overview of surface modification and coating techniques for plastics is presented for changing the surface properties to meet the performance requirements in a variety of applications. Surface modification and coatings are utilized for purposes of adhesion, wettability, biocompatibility, scratch and abrasion resistance, chemical resistance, barrier properties, and more. Methods for modification include physical processes, such as surface roughening and abrading; liquid chemical processes, such as acid etching; and reactive gas chemical processes. The reactive gas chemical processes covered include corona, flame, and low-temperature plasma. Surface degradation from reactive gas exposure is presented with respect to the sources, chemical mechanisms, and methods for characterization. Coatings for plastics, including paints, functional coatings, and metallization, are summarized.

The hydrophobic characteristic of polymers is considered a limiting property for its applications. To some extent, this has been overcome by techniques such as non-thermal plasma, which, even with a few seconds of application, can increase the surface energy and hydrophilic character of polymers. However, this technique is associated with advantages and disadvantages. Surface degradation related to oxidation and crosslinking are considered irreversible changes, in most cases, while the hydrophobic character is quickly restored, presenting a challenge to researchers all over the world. As a reversible behavior, efforts have been made to understand this particular characteristic of the hydrophobic recovery (or the aging effect) of polymers. The application of non-thermal plasma on polymeric surfaces has also been used in biomedicine as a sterilization device to control the growth of biofilms, as well as to increase the biocompatibility of prosthetic surfaces. This chapter discusses some particular characteristics of polyolefins exposed to plasma.