Curing quality control with DMA
Knowledge of the degree of polymerization is important to ensure that the nominal mechanical properties of a polymer matrix are achieved. Insufficient polymerization can lead to insufficient adhesion between fiber layers, or skins and cores, and to potential geometric distortions during demolding.
In the example opposite, in test no. 1, a specimen of an epoxy-based material is tested on a temperature ramp up to 250°C; it shows a spread glass transition with two Tan Delta peaks.
A second consecutive identical test no. 2 reveals a sharper glass transition with a much higher amplitude Tan Delta. Test no. 2 shows that the specimen was initially poorly hardened and was post-cured during test no. 1.
A third consecutive test shows E’ and Tan Delta fully superimposed on test no. 2, demonstrating that nominal mechanical properties have been achieved.
