Nanoindentation to Determine Young’s Modulus for Thermoplastic Polymers

A simple method for measuring the Young's modulus of thermoplastic polymers at the nanoscale is proposed. Nanoindentation tests have been carried out on three polymers (ABS, PET and PP) using the Berkovich indenter tip. The elasticity moduli obtained from the reduced moduli thanks to the slope of the initial part of the discharge curve were greater than the real moduli of these polymers. For this, a simple method is proposed to minimize the error made on the determination of the modulus which is based on the calculation of several stiffnesses between 10 and 98% of the maximum load on the experimental unloading curve. The results show that the calculated moduli at a load less than 50% of the maximum load were close to the macroscopic moduli and the effect of viscosity was minimized. In the end, the elastic Young's modulus obtained by our approach is in very good agreement with the result of the tensile tests.