Paper surface energetics

The scope of the present paper is to emphasize that the interactions between support, metal and atmosphere are responsible for both the physical (size distribution, shape of the crystallites, wettability of the substrate by the crystallites and vice versa), the chemical and the catalytic (suppression of chemisorption, increased activity for methanation, etc.) manifestations of the supported metal catalysts. In the next section of the paper, a few experimental results concerning the behaviour of iron crystallites on alumina are presented to illustrate the role of the strong chemical interactions between the substrate and the compounds of the metal formed in the chemical atmosphere. Surface energetic considerations, similar to those already employed by the author (7,8), are then used to explain some of the observed phenomena. Subsequently, the Tauster effect is explained as a result of the migration, driven by strong interactions,... 

Paper wettability by polystyrene based toner has been studied by Lee (3). Wax/polymer coating of paper and paperboard has been investigated by Swanson and Becher (4), Glossman (5 ), and more recently by Fredholm and Westfelt (60. In the coating studies it was believed that surface energetics of the paper structure played a fundamental role in the spreading process and subsequent adhesion of polymer to the paper surface. 

TABLE I. SURFACE ENERGETICS OF CELLULOSE FILMS AND PAPERS... 

Since the first review on the effect of surface energetics on polymer friction and wear published in 197, (0 many new works have appeared. Some of these papers(2- ) are on fracture mechanics. In this paper we shall review our current knowledge about both fracture energetics and surface energetics of polymer wear. First, we discuss wear mechanisms and then emphasize these two aspects related to each wear mechanism. 

In comparison with metals, most conventional polymers are low in wear resistance. For wear control, we need to understand various wear mechanisms for each polymer system (V). As discussed in a previous paper, for adhesive wear, surface energetics can determine the extent of surface wear. Thus, a low surface energy is preferred to minimize the surface attrition. In addition, a harder polymer is desired to lower the wear rate. For abrasive wear, fracture energetics become important a harder and tougher material should be more wear resistant. 

Several papers by Kendall treated the subject of adhesion rather explicitly with simple models of mechanics. Andrews and Kinloch attempted to separate "adhesion" and "adhesive joint strength" and established that the intrinsic failure energy is close to the work of adhesion when pure interfacial failure occurs. Kloubek attributed the interaction of polar forces to the contribution of the work of adhesion. The effect of surface energetics and wetting on adhesion has been summarized by Kaelble, Mittal, and Zisman . ... 

After Dr. Tabor s paper, I shall survey the effects of surface energetics on polymer friction and wear. I hope that my paper will provide some insight about various interactions at the interface. 

Friction and wear involve sol id-to-solid contacts governed by Van der Waals and electrostatic interactions on the surface of a friction pair. Thus, surface energetics could play a major role in determining polymer friction, if deformation of bulk were not accompanying the contact phenomena. This paper discusses both the relevance and irrelevance of surface energetics to polymer fri ction. 

This paper will discuss the relevance and the irrelevance of surface energetics to polymer friction and wear. This survey covers most of the important works published in the past and during this recent Symposium. Since basic principles related to polymer friction have been reviewed by Tabor, and by Savkoor, the scope of this discussion will be limited to pertinent friction mechanisms with emphasis on surface interactions. First will be a brief discussion of the following friction processes polymer sliding, elastomer sliding, lubricated polymer sliding, polymer rolling. 

Then the main part of this paper deals with the effect of surface energetics on sliding friction, followed by examining multiple adhesion components of friction force - backgrounds and actual examples. Thus, it is necessary to distinguish van der Waals and electrostatic interactions. For Van der Waals interactions, we describe basic components of each type of force for both microscopic and macroscopic bodies. 

The interaction of an electron with a surface produces at least three phenomena which are important in a plasma environment. They are (1) chemical reactions between gas phase species and a surface where electron bombardment is required to activate the process, (2) electron-induced secondary-electron emission, and (3) electron-induced dissociation of sorbed molecules. A fourth phenomenon — lattice damage produced by energetic electrons — depends sensitively upon the properties of the material being bombarded, and, it is important in specialized situations, but it will not be discussed in this paper. 

Surface aggregates formed by ionic surfactant adsorption on oppositely charge surfaces have been shown to be bi layered structures (1.) and are called admicelles<2) in this paper, though they are sometimes referred to as hemimicelles. The concentration at which admicelles first form on the most energetic surface patch is called the Critical Admicellar Concentration (CAC) in analogy to the Critical Micelle Concentration (CMC), where micelles are first formed. Again, in much of the literature, the CAC is referred to as the Hemimicellar Concentration (HMC). 

Several simulation models have been introduced in the past for surface reactions, including energetic interactions [16, 35-37]. These models are very difficult to compare to each other because they use very different descriptions of the individual reaction steps. Furthermore, steps which are considered to be independent of energetic interactions in one paper, show a dependency in another paper. Therefore it is necessary and useful to introduce a kind of the standard model [38] in order to compare different models in the future. 

It has been the purpose of this paper to provide an overview of the basic differences and similarities of the various types of Instruments which detect Ionized particles emitted from surfaces by energetic particle bombardment. Since the scope of secondary ion mass spectrometry Is so broad, It is not surprising that no one Instrument has been designed to perform optimally for all types of SIMS analyses. Design aspects of the primary beam, extraction optics, mass spectrometer, detection equipment and vacuum system must be considered to construct an Instrument best suited for a particular purpose. 

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