Thermal degradation of 3D printing processed polylactide samples by means of vibrational spectroscopy

Abstract

In the present study, we utilized the fused deposition modeling technique (FDM) to prepare polylactide (PLA) samples and evaluate in real time their thermal degradation by means of vibrational spectroscopy. The FDM method is probably the most popular technology among 3D printing technologies due to the inexpensive and flexible extrusion systems used for the handling of several thermoplastic materials. Nevertheless, a thermal degradation phenomenon of the 3D-printed thermoplastic PLA samples occurs, which is an inevitable issue for long-term reliability of the material leading to poor product properties. We recorded the Fourier transform infrared spectra in real-time mode to monitor the thermal degradation kinetics of PLA samples at a specific temperature below the glass transition point and explore the induced structural alterations. The absorbance of specific spectral features was used to evaluate the concentration reduction of PLA functional groups during the thermal degradation process. The kinetics of the thermal degradation was estimated by means of the absorbance of the C-COO band which reflects the scission of the ester linkage due to degradation process. The kinetic rate constant was found Kt = 2.30 × 10−3 s−1. The results reported in this work were analyzed and discussed in view of relevant data reported for PLA samples prepared with traditional mechanical processing.