Paper surface properties

In the pulp and paper industry, anionic and cationic acrylamide polymers are used as chemical additives or processing aids. The positive effect is achieved due to a fuller retention of the filler (basically kaoline) in the paper pulp, so that the structure of the paper sheet surface layer improves. Copolymers of acrylamide with vi-nylamine not only attach better qualities to the surface layer of.paper, they also add to the tensile properties of paper in the wet state. Paper reinforcement with anionic polymers is due to the formation of complexes between the polymer additive and ions of Cr and Cu incorporated in the paper pulp. The direct effect of acrylamide polymers on strength increases and improved surface properties of paper sheets is accompanied by a fuller extraction of metallic ions (iron and cobalt, in addition to those mentioned above), which improves effluent water quality. 

Other noncontact AFM methods have also been used to study the structure of water films and droplets [27,28]. Each has its own merits and will not be discussed in detail here. Often, however, many noncontact methods involve an oscillation of the lever in or out of mechanical resonance, which brings the tip too close to the liquid surface to ensure a truly nonperturbative imaging, at least for low-viscosity liquids. A simple technique developed in 1994 in the authors laboratory not only solves most of these problems but in addition provides new information on surface properties. It has been named scanning polarization force microscopy (SPFM) [29-31]. SPFM not only provides the topographic stracture, but allows also the study of local dielectric properties and even molecular orientation of the liquid. The remainder of this paper is devoted to reviewing the use of SPFM for wetting studies. 

Electrokinetic processes are widely used in different fields of science and technology. We had already mentioned the use of electrokinetic processes for research into the electric properties of surface layers of insulating materials. Such measurements are used, in particular, when studying the surface properties of polymeric materials, their behavior in different media, and their interactions with other materials (e.g., with adsorbing surface-active substances). The results of this research are used in textile, cellulose and paper, and other industries. 

The aim of this paper is not to add to the current debate but to present a simple graphical method of analysing the free energy of formation of the electrical double layer at the oxide/solution interface ( 1). This will provide a simple way of visualizing the complementary roles of chemical reactions or surface properties of... 

Most earlier papers dealt with the mercury electrode because of its unique and convenient features, such as surface cleanness, smoothness, isotropic surface properties, and wide range of ideal polarizability. These properties are gener y uncharacteristic of solid metal electrodes, so the results of the sohd met electrolyte interface studies are not as explicit as they are for mercury and are often more controversial. This has been shown by Bockris and Jeng, who studied adsorption of 19 different organic compounds on polycrystaUine platinum electrodes in 0.0 IM HCl solution using a radiotracer method, eUipsometry, and Fourier Transform Infrared Spectroscopy. The authors have determined and discussed adsorption isotherms and the kinetics of adsorption of the studied compounds. Their results were later critically reviewed by Wieckowski. ... 

Despite the variations in the surface properties of silica, it is remarkable that such good agreement exists. It would appear that the data in the earlier paper of Sidorov 165) are unreliable. 

In this paper, XPS and Raman spectroscopy have been used to study the chemical state and location of Ni and V contaminants. The effects of thermal and hydrothermal treatments on catalyst surface properties, and the role of sepiolite in promoting metals tolerance has been observed and reported. 

Detailed information, background reviews, or highlights from the authors about the specific properties of PFCs and fluorinated colloids in relation to biomedical applications can be found in Refs. [3-9]. These papers also provide insight into the surface properties of PFCs, their hydrophobic and lipophobic characters, self-aggregation properties, tendency to stabilize interfaces, and ability to promote nanocompartmentation in self-assembled systems. 

This paper is devoted to the sorption of uranyl, which exhibits a complex aqueous and surface chemistry. We review briefly the sorption behaviour of An in the environment, and illustrate the variety of environmental processes using published data of uranyl sorption in the Ban-gombe natural reactor zone. After summarizing the general findings of the mechanisms of An sorption, we then focus particularly on the current knowledge of the mechanisms of uranyl sorption. A major area of research is the influence of the aqueous uranyl speciation on the uranyl surface species. Spectroscopic data of U(VI) sorbed onto silica and alumina minerals are examined and used to discuss the role of aqueous uranyl polynuclear species, U02(0H)2 colloids and uranyl-carbonate complexes. The influence of the mineral surface properties on the mechanisms of sorption is also discussed. 

Despite the important role that EPR plays in the characterisation of the surface properties of these transition metal oxides, virtually all of the published papers have continued to utilise traditional cw X-band EPR even though high frequencies and/or additional EPR techniques (such as ENDOR, HYSCORE or ESEEM) could offer enormous advantages. 

In this paper, we will report the electronic and catalytic reactivities of the model VC/V(110) surface, and our attempt to extend them to VC powder catalysts. By using high-resolution electron energy loss spectroscopy (HREELS) and NEXAFS techniques, we observed that the surface properties of V(110) could be significantly modified by the formation of vanadium carbide some of the experimental results on these model surfaces were published previously.3-5 We will discuss the selective activation of the C-H bond of isobutane and the C=C bond of isobutene on V(110) and on VC/V(110) model systems. These results will be compared to the catalytic performances of vanadium and vanadium carbide powder materials in the dehydrogenation of isobutane. 

Mullins (48-50) published a series of papers detailing the mass-transfer processes which leads to the flattening of corrugated surfaces and thermal grooving. Assuming a nearly flat crystal surface, with surface properties independent of orientation, Mullins showed that the equation... 

Transmission IR still remains the best method for examining insulating oxide surfaces and over the past decade there has developed a considerable understanding of many surfaces, particularly those of silica, alumina, molecular sieves and complex catalysts. The objective of this paper, therefore, will be to demonstrate how some of the recent advances have been made. Clearly it is not possible to discuss all the materials studied by transmission IR and the author has chosen to use the surface properties of silica to illustrate the type of understanding that is now available. 

While paper can be made of wood fibers alone, little is actually made without some chemical addition or modification. These chemical additives are used to either assist in papermaking or to give the paper certain desirable end-use qualities. These chemicals can be added at virtually any step in papermaking. Some of the additives are used to influence the entire sheet properties. These chemicals are added to the pulp slurry prior to sheet formation (internal addition). When the surface properties of the sheet also need to be altered, additives are used on the sheet after some period of formation or drying (external addition). A number of these chemicals serve commonly as both internal or external additions. 

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