Depth sensing indentation analysis of electrochemically synthesized polythiophene

A depth sensing indentation (DSI) test with associated analyses was used to investigate some mechanical properties (reduced elastic modulus, hardness and creep) of electrochemically synthesized polythiophene (PT). Internal friction (IF) and energy absorption representing the degree of anelastic deformation of the material were also determined using cyclic and step-load/unload (SLU) test procedure, respectively. The indentation load–displacement (P–h) curves of the sample were obtained under different peak loads with two load holding time, 70 and 300 s. Elastic modulus values were determined by analyzing of these curves with Oliver–Pharr (O–P) and Feng–Ngan (F–N) procedures. The obtained results pointed out that both methods yielded comparable results for 300 s, while the corresponding values of 70 s were not well-matched with each other. These results were explained by the saturation of creep effects within 300 s holding period. Creep analysis exhibited that creep displacement increases at a declining rate with time and finally reaches a constant rate. Cyclic test results indicated that IF values approach saturation after several cycles and the saturation value of IF was found to be depending on loading rate. From SLU tests, an upper limit of the normalized dissipated energy was observed.