Adhesives Based on Acrylic Polymer Mixtures

Let us consider the effect of PBMA particles precipitated from polymerizing MMA or from its mixture with butyl methacrylate (BMA) on 

For the monomer polymerization at room temperature, the adhesive was augmented with a redox system of 3% BP and 0.75% DMA. To study, explain, and predict the development of the elastic failure of the polymer in the adhesive interlayer, an improved method of investigating adhesive layer crack resistance with modeling of the formation and growth of a crack at the adhesive-honded joint loading was used [119]. Five adhesive-bonded joints with the adhesive mixture compositions shown in Table 3.1 were subjected to static tests for crack resistance at room temperature. The characteristics of the static crack resistance of the adhesive-bonded joint Kic is the coefficient of the stresses intensity Gic is the intensity of the elastic energy release ic is the opening in the crack tip) were determined at the moment of onset of the crack in double-cantilever specimens DCB (Fig. 3.5). The specimen cantilevers were made of PMMA of TOCH type. 

The optical transparency of the cemented material allowed visual detection of the moment of crack onset. In this case the load Pi, the shift of the point of its application i p, and the crack face displacement close to the mid-point of its front were recorded (Fig. 3.5). Determination of the critical load Pc from graphs of P- p and P- c using the secant method gave good agreement with the results obtained by visual detection of the crack onset. 

The values of Kq for the specimens and the crack sizes met the well-known requirements of applicability of plane deformation conditions that ensure the equality = Kiq. The fact that the acquired values of Kq are equal to the characteristic Kiq of the adhesive interlayer indicates their independence of the crack length, the insignificant deviation from linearity of the P—and P—6q graphs, the absence of drawing of the crack tip, and the approximation of its front to a straight line. 

The possibility of multiple initiation and arrest of the crack in the DCB specimen validates the application of the method of mechanical compliance for determining the characteristic energy Gjc. Values of Gic for the adhesive-bonded joints under test were calculated from 

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