Ultrasonic speed measurements for polylactic acid (PLA) characterization

PLA is a polymeric material widely used for 3D printing, with varied applications in medicine and engineering, among others. In many applications, it is important to determine mechanical properties, such as speed of sound (SoS), density and acoustic impedance, which are very susceptible to printing parameters such as nozzle diameter, temperature and infill density. Even when the use of PLA is very extended, there is a lack of information about the SoS, and important discrepancies among the results presented in the few works reporting experimental data. Therefore, we determined the SoS of PLA samples using acoustic waves of 1.68 MHz, and we compare the results with measurements carried out at higher frequencies to explore relaxation and dispersion processes. Keywords