Photo-oxidation effects on mechanical properties of epoxy matrixes: Young's modulus and hardness analyses by nano-indentation

The influence of photo-oxidation on Young's modulus (E) and hardness (H) variations of two epoxy matrixes (DGEBA-MTHPA and DGEBA-IPDA) has been investigated using a Nano-Indentation test. The results show that these mechanical properties increase with irradiation time for both systems and continuously decrease with the indentation depth. These decreases are characteristic of the presence of a hard film on a softer substrate [Int. J. Solids Struct. 24 (1988) 1287]. Indeed, it was shown that the photo-degradation of these polymers leads to the formation of a thin photo-oxidation layer at the matrix's surface.