Rapid breaks of metal-polymer-metal adhesive specimens have shown the presence of a charge density on the metallic surface, provided the break occurs at the metal-polymer interface, and a much smaller charge if it occurs in the interior of the polymer. This is analyzed in terms of the electron atmosphere existing external to the metal in a dielectric region of low barrier. The barrier values in certain cases are otherwise known to be of appropriate order of magnitude. Measured experimental surface charge densities permit estimation of the maximum limit of barrier height. Because of the presence of the charge distribution in the polymer, there is an electrostatic force on the adherend metal directed toward the dielectric polymer, which represents a contribution to the total adhesive forces opposing break. Such electrostatic contributions to adhesion have not previously been considered; their order of magnitude and their relation to the thickness of the adhesive are discussed. The qualitative agreement between the theory and a number of previously unexplained experimental results in the literature is shown.
Adhesion Using Molecular Models Adhesion of Polyethylene and Poly(vinyl Chloride) to Metals To learn how to select the most suitable adhesive for use on a given metal surface, scale models of molecules of high polymers and metal surfacestitanium, stainless steel, and iron -were prepared and fitted together, and the adhesive force was calculated for various combinations. The geometric arrangement of adhesive molecules on metal surfaces has a strong effect on the adhesive force between the two. Calculated adhesive forces based on
Man is incurably empirical. When a given experiment fails to produce the expected result, he says it will not work. Whereas, were he neither empirical nor dogmatic he would say that it does not work.When egg albumin or egg white, as the case may be, is heated to a certain temperature, coagulation of the suspended particles takes place. Because people, in the past, failed to repeptize the gel so formed, it has been tacitly assumed that it cannot be restored chemically unaltered, at least, to the original colloidal state. Some profound change has been held responsible for this failure of the albumin to repeptize. This apparent set of circumstances left an opportunity open to coin a word; the term "denaturation" or "denaturization" resulted inevitably.Much has been written about "denaturation", for instance, the following:* 1 * This work is part of the programme now being carried out at
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