Epoxy-phenolic adhesives, effects temperature

Fig. 119. Effect of storage at elevated temperatures on room temperature strength of stainless steel lap shear joints with an epoxy-phenolic adhesive (Hidux 1197A, Ciba-Geigy) (adapted from Althof, 1966).

Fig. 120. Effect of elevated temperature on sustained load. Stainless steel adherends, epoxy-phenolic adhesive (Hidux 1197A). The lines are drawn as lower envelopes of the range of the data points to the same scale as Fig. 119 (adapted from Althof, 1%6).

FIGURE 7.1 The effect of temperature on the tensile shear strength of modified epoxy-phenolic compared to other hybrid adhesives (substrate is aluminum).4... 

In general, the elastomer must be prereacted (adducted) with the epoxy for the toughening effect to take place. Adducts reduce the likelihood of early phase separation and maintain the solubility of the elastomer in the uncured resin system. For CTBN the reaction is carried out at high temperatures (150 to 160°C) and usually in the presence of a catalyst, such as tris-dimethylamino phenol or piperidine. The resulting epoxy-CTBN adducts are available from several suppliers, and they can be easily formulated into epoxy adhesives. 

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