Dispersed rubbery phase

Figure 5. Schematic effect of the volume fraction of the dispersed rubbery phase on E E", and tan 5 of a two-phase system...

Semi-empirical rules, which correlate the static glass transition temperature Ty from differential thermal analysis or dilatometry with the dynamic T(J taken from the tan 8 or E" peak, may be used with caution in analyzing two-phase systems with a dispersed rubbery phase. The dynamic Tg depends on the rubber phase volume, and it may be shifted further toward lower temperature for effectively crosslinked and grafted rubber particles because of dilatation. 

Figure 1.2 In an overloaded toughened adhesive, crack propagation is stopped by the dispersed rubbery phase.

Figure 5.2 Electron micrograph of the typical microstructure of a rubber-toughened epoxy adhesive showing the dispersed rubbery phase of particles in the matrix of a thermosetting epoxy polymer. (TTie wavy lines are artefacts due to the cutting of a very thin section of material.)...

This tendency for an overloaded joint to fail catastrophically when distorted has been substantially suppressed by the introduction of the toughened adhesives. These adhesives resist crack propagation by incorporating a dispersed rubbery phase within the harder load-bearing portion of the adhesive (Fig. 7.3). When the joint is overloaded... 

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