Dynamics of the strength of adhesive-bond joints between polymers and steel

We have investigated the time dependences of the strength of adhesive bonds between polymers (epoxy adhesive and polyamide) and steel 45 at various temperatures. These dependences have been determined based on the rates of two opposite processes, viz., an increase in strength due to the formation of coordination bonds between polymer molecules and Fe$^{2+}$ ions and a decrease in strength due to ruptures of adhesive or polyamide molecules under the effect of internal stresses. The values of activation energy of these processes have been determined.