Role of diffusion in the formation of adhesion bonds between polymers

So-called "direct" proofs of self- and mutual-diffusion in the formation of adhesion bonds between polymers [3] are discussed critically. It is shown that in reality none of these direct proofs can be regarded as such. Accordingly, the question of the validity of the diffusion mechanism of adhesion as applied to thermodynamically incompatible or only "partly compatible" polymers remains open.Mekhanika Polimerov, Vol. 3, No. 5, pp. 850–853, 1967     

Local compatibility and the adhesion of polymers

The role of the thermodynamic factor in creating an adhesion bond between partly or wholly compatible polymers is discussed. The importance of this factor depends on the fact that polymers brought into contact will diffuse into each other only if they are wholly or partly mutually soluble. This mutual solubility is confined to a surface layer and is determined by the local diffusion. In considering the mechanism of formation of an adhesion bond between two polymers it is necessary to take their surface properties into account. In the diffusion theory of adhesion diffusion is regarded as the motive force in the creation of an adhesion bond.Moscow Lomonosov Institute of Fine Chemical Technology. Translated from Mekhanika Polimerov, No. 3, pp. 455–459, May–June, 1969.     

Effect of the conditions of bond formation and destruction on the adhesion of polymers to synthetic fibers

It is shown that the adhesion of linear polymers can be measured by shearing a monofilament relative to a microblock of adhesive [1]. Experiments have been performed on polypropylene, polyethylene terephthaliate, polycaprolactam, polyvinyl alcohol, and glass fibers. Broad variation of the diameter, structure, and physicomechanical properties of the various kinds of oriented fibers had practically no effect on the adhesion. The physicochemical properties of the adhesive solutions at the moment of application to the fiber likewise do not affect the adhesion which, other things being equal, is determined by the nature and supermolecular structure of the polymers in the contact zone.Belorussian Lenin State University, Minsk. Branch of the Karpov Scientific-Research Physicochemical Institute, Obninsk. Translated from Mekhanika Polimerov, No. 6, pp. 1042–1048, November–December, 1970.     

Reversible changes in the adhesion of polymers to solid surfaces

The adhesion of low-density polyethylene to steel and glass changes when water and acid molecules penetrate to the polymer-substrate interface. Their removal leads to total or partial recovery of the initial adhesion. An adhesive bond between polyethylene and the substrate was observed at room temperature as well as at 50° C. The results are explained in terms of the dynamic adsorption-desorption behavior of polyethylene adhesion. It is suggested that the adhesion is based is based on the van der Waals interaction between the substrate and the polar surface groups of the polymer.Mekhanika Polimerov, Vol. 4, No. 2, pp. 309–313, 1968     

Reversible changes in the adhesion of polymers to solid surfaces

The adhesion properties of coatings of polycrystalline hexafluoropropylene—vinylidene fluoride copolymer on steel and glass have been investigated. Coatings formed at 200–240° C suffer a reversible loss of adhesion following the diffusion of water and acid molecules to the interface, which is attributable to the mobile adsorption-desorption nature of the adhesion of this particular copolymer to steel and glass. Heat treatment at 280° C gives the coating improved resistance to the debonding action of water.Ural Scientific-Research Chemical Institute, Sverdlovsk. Moscow Institute of Fine Chemical Technology. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1065–1070, November–December, 1968.     

Factors in the adhesion strength of polymers toward a solid substrate

The true adhesion is looked upon as the sum of the experimentally determined strength of the glued area, internal stresses, and unaccountable technological losses (unrealized contacts). It has been established that the internal stresses do not depend on the value of the adhesion strength.Translated from Mekhanika Polimerov, No. 2, pp. 356–359, March–April, 1976.     

Relation between the strength of polyethylene-steel adhesion bonds and the thickness of the ultrathin layer of polymer remaining on the surface of the metal

On the basis of the principle of ellipsometry and, moreover, the method of pyrolitic decomposition of the polymer with subsequent chromatographic analysis of the products of pyrolysis, a procedure has been developed for experimentally determining the thickness of the ultrathin layer of polymer that remains on the metal after failure of a polyethylene-steel adhesion bond. The nature of the relationship between the thickness of the residual polymer layer (200–800 Å) and the strength of the adhesion bond is established. It is concluded that the cohesion strength and the deformation at failure of the layer of adhesive next to the more rigid and stronger boundary layer have a decisive influence on the strength of the adhesion bond.Riga Polytechnic Institute. Translated from Mekhanika Polimerov, No. 3, pp. 420–424, May–June, 1976.     

Dissipative solutions for equations of viscoelastic diffusion in polymers

We study the system of differential equations which describes the diffusion of a penetrant liquid in a polymer. We construct dissipative solutions to the Cauchy problem for this system in the space.     

Experimental mathematics and proofs in the classroom

Experimental mathematics is a serious branch of mathematics that starts gaining attention both in mathematics education and research. We given examples of using experimental techniques (not only) on the classroom. At first sight it seems that introducing experiments will weaken the formal rules and the abstractness of mathematics that are considered a valuable contribution to education as a whole. By putting proof and experiment side by side we show how this can be avoided. We also highlight consequences of experimentation for educational computer software.     

Algorithmic proofs of two relations between connectivity and the 1-factors of a graph

An algorithm is used to give simple proofs of these two known relations in the theory of matched graphs: A graph with a unique 1-factor contains a matched bridge; an n-connected graph with a 1-factor has at least n totally covered vertices, if n?2. Conditions for exactly n, or more than n, totally covered vertices are also given.     

Closed categories and the theory of proofs

The main aim of this article is to suggest a translation of the simplest concepts of category theory into the language of (structural) theory of proofs, to use this translation to simplify the proofs of some known results [1], and to obtain two new ones: the coherence theorem for canonical morphisms in (nonmonoidal, nonsymmetric) closed categories [2], and the solution of the problem of equality of canonical morphisms. Extensions of these results to monoidal closed, symmetric closed, and monoidal symmetric closed categories are sketched. The decision procedure is obtained by means of a correct and faithful translation of canonical morphisms into an expansion of the -language, which has the tools for a special account of superfluous premises of implications (the thinning rule). The expansions of the -language which have so far appeared in the literature have not possessed this facility.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Institute, im. V. A. Steklova AN SSSR, Vol. 68, pp. 83–114, 1977.     

Effect of submicroscopic crack formation and relaxation phenomena in polymers

The development of submicrocracks and the changes taking place in their concentration during loading and unloading cycles were studied by the low-angle x-ray scattering method in oriented amorphous-crystalline polymers (capron and polypropylene). The deformation () of the polymers was compared with the changes in submicrocrack concentration (N_cr).A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 3, pp. 387–392, May–June, 1970.