The Status of the Theory of Bond Strength in Multiply Articles

Abstract

Abstract 1. Ply separation of multiply specimens and articles, operating under conditions of repeated deformation, is a result of fatigue of the boundary layer. 2. The development of the process of fatigue is determined by the structure and composition of the fatigued material, and also by the pattern of action. 3. The difference of fatigue of the boundary layer from the fatigue of uniform masses of material is governed by their difference in composition and structure, and also by the difference in the patterns of deformations of the boundary layer and of the uniform materials. 4. The formulation, technological and physical chemical factors, which influence each other mutually, determine the structure and compositions of the boundary layer which is eventually formed in the process of contacting the surfaces and vulcanization. 5. The pattern of action of the mechanical forces upon the boundary layer is determined by the applied external forces or deformations, by the construction of the multiply specimen or article and by the ratio of the elastic characteristics of the material (Young's modulus and Poisson's coefficient). 6. The formation of principles of a theory of bond strength between the elements of multiply articles is possible only by ascertaining the mechanism of fatigue of the boundary layer. For this we require the investigation of the viscoelastic properties of the raw stocks, of the phenomena which take place at surfaces of uniform raw stocks and of pliedup raw stocks, and of the process of vulcanization in the boundary layer. All these questions must be investigated as a complex, i.e., with consideration of the internal bonds existing between the formulation, technological and physical chemical factors. In addition it is necessary to analyze the influence of the construction and the elastic properties of the materials upon the character of the stresses, which arise in the joint zone. 7. A further major task in the theory of bond strength is the theoretical consideration of the nature of the tackiness of raw stocks and of the mechanism of the action of bonding agents.