Writing paper chemical additives

Modem papers, which were invented after the revolutionary changes of one hundred years ago, have serious problems—either in permanence or in durability. Most paper produced from wood fibers does not show the permanence of rag papers and discoloration is more critical than in rag papers. It has been noted that modern writing papers and books tend to have a much shorter life expectancy than those manufactured one hundred years ago (4-9). In essence, the increased use of wood fibers, the use of chemical additives (especially those promoting increased acidity), and environmental conditions have been given to account for these results. The literature dealing with these topics is now very large it would not be wise to attempt an extensive review here in addition to those that already exist (6,10-19). It is my intention in this chapter to consider the discoloration of modern papers, and the inhibition or the control of discoloration. 

The Gibbs phase rule is the basis for organizing the models. In general, the number of independent variables (degrees of freedom) is equal to the number of variables minus the number of independent relationships. For each unique phase equilibria, we may write one independent relationship. In addition to this (with no other special stipulations), we may write one additional independent relationship to maintain electroneutrality. Table I summarizes the chemical constituents considered as variables in this study and by means of chemical reactions depicts independent relationships. (Throughout the paper, activity coefficients are calculated by the Debye-Hiickel relationship). Since there are no data available on pressure dependence, pressure is considered a constant at 1 atm. Sulfate and chloride are not considered variables because little specific data concerning their equilibria are available. Sulfate may be involved in a redox reaction with iron sulfides (e.g., hydrotroilite), and/or it may be in equilibrium with barite (BaS04) or some solid solution combinations. Chloride may reach no simple chemical equilibrium with respect to a phase. Therefore, these two ions are considered only to the... 

Chemical Characteristics of Paper Documents. From the earliest times up to the present day, the substances used as vehicles for writing have been numerous. Ancient paper documents were basically made from rags of cotton and linters cellulose is the major chemical constituent (I). Modern papers, however, are made of wood fibers, which usually are composed of cellulose, hemicelluloses, and lignin (I). In addition, for most of the modern papers, fillers, sizing agents, and other additives are used to improve paper properties (I). 

The calculation of relaxation amplitudes by temperature jump is complex, except for very simple systems of the type A B or A + B C. This is unlike their calculation by concentration jump, since, in this case, the perturbation occurs at constant T and P, and the equilibrium constants remain unchanged. Moreover, we shov in this paper, that by proper use of the concentration jump method, one is able to measure the equilibrium constants of complicated as well as simple chemical systems. Whenever possible, the perturbation should be performed by rapidly modifying the concentration of a species that is characteristic of the type of reaction studied H or 0H for proton transfer, nucleophile for nucleophilic addition or substitution, etc... Thus, one can always write Z [X ] (t) = C, where represents the different... 

In this chapter, we have reviewed the covariance approach—one promising strategy toward efficient acquisition of information from a limited number of data sets. We have seen the fruitful outcomes of covariance NMR spectroscopy, including its applications to soHd-state NMR studies of chemically or biologically important systems, its improvements to enhance the efficiency further, and its modifications to accommodate various needs of structural analysis. In addition, the question regarding the inner-product spectroscopy, to be answered in future studies, has been posted. At the moment of writing this review, covariance NMR spectroscopy is rather young and the number of relevant papers is not many. From... 

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