Ultrasonic evaluation of aging kinetics in amorphous polymer.

The physical aging of amorphous polymers induces changes in material properties, which are challenging to detect in situ in industrial settings. Here, we present a nondestructive nonlinear ultrasonic evaluation technique that enables localized measurements of the combined effects of temperature and time in amorphous polymers, without needing to remove materials. The proposed technique is demonstrated using commercial grade poly(vinyl chloride) samples and is supported by analysis of wave–material interactions. The results show that the physical aging of the polymer is described by the Arrhenius equation with an effective activation energy of 103 kJ/mol over the analyzed temperature range. [ABSTRACT FROM AUTHOR]