Monitoring strains and stresses during cure. The red curve in Figure corresponds to BADGE/JeffAmine cured at 50 %RH. The cure strain, Ɛcure, decreased continuously during the 48 hrs and shows a typical degree-of-cure profile as a function of time for epoxy glues; that is an initial fast characteristic time (first hour) with a decrease in strain and increase in strain (molecular forces driving the surfaces towards each other during cure), followed by a slower (several hours) characteristic time with a continuing decrease in strain and increase in strain. The abrupt jump at tcure ≈ 15 hrs was caused by drift and migration of the PCA from the imaging field of view. The last curing experiment example is at 100 %RH, black curves in Figure . The spring constant used to monitor and calculate stress was k ≈ 2,500 N/m. Similar to what was observed for the 50 %RH humidity condition, the curve showed two characteristic time scales: an initially fast increase in strain corresponding to a fast degree of cure, followed by slower characteristic time, where the degree of cure happens much slower. The measured cure stress is within the same order of magnitude, between 250-500 kPa.