Viscoelasticity of Adhesion

Another consideration in the nse of adhesives in structural members is creep. In very rigid structures composed of steel, aluminum, or fiber-reinforced composites. 

FIGURE 11.7 Time-temperature transformation of adhesion data. (Adapted from Turreda, L. D., Hatano, Y., and Mixumachi, H., Holzforschung, 45, 371-375,1991.) 

FIGURE 11.8 Master curve for various carbon fiber/epoxy systems. (Adapted from Rao, V. and Drzal, L. T., Journal of Adhesion, 37, 83-95, 1992.) 

While adhesion is typically rate and temperature dqjoident, many adhesive systems do not behave in a manner that is amenable to time-tenperatuie transformation. 

As with all other polymeric applications, a large number of polymeric adhesive systems exist. However, for the sake of brevity, only the generic families of adhesives will be discussed. 

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Since measurement is the first step in understanding material properties, we must have a grasp of rheometry, the measurement of the flow and deformation properties of materials. Of the many the methods used to measure Newtonian viscosities and Hookean elasticities, only a few can be readily adapted to the nonlinear viscosities and viscoelasticities of adhesives. 

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