Accurate Evaluation of Dynamics and Specific Interactions in PLA/TiO2 Nanocomposites

Abstract

Near infrared spectroscopy in the transmission mode was used to study the effect of the presence of TiO 2 nanoparticles on the dynamics of Polylactic Acid (PLA) in PLA/TiO 2 nanocomposites. The variation of IR absorbance of certain bands, the average energy of those absorptions (< v >, cm -1) and two-dimensional Infrared (2D IR) correlation spectroscopy as a function of temperature and TiO 2 content (0, 1, 5 and 10% wt) were used. Thermal transitions associated to the glass transition (64 ºC) and cold crystallization temperatures (123 °C) are clearly identified from the analysis of integrated absorbance of bands at 4770 and 4725 cm -1 , assigned to amorphous phase, as they were more sensitive to temperature changes. The band at 4440 cm -1 , related with the formation of crystalline regions, showed a better definition of the thermal transitions as well as the bands at 4307 and 4255 cm -1 associated to the combination of C-H wagging modes showed sharp changes, suggesting that transitions occur due to backbone conformational changes. The evolution of integrated absorbance of different bands in PLA-TiO 2 nanocomposites as a function of temperature, seem to point out the presence of specific interactions between the C = O group and TiO 2 nanoparticles. This effect is observed up to 1% wt whereas for higher loadings it is not possible to detect thermal transitions due to the scattered of the data for higher loadings of particles.

Preparation and Characterization of Polymer Composite Materials Based on PLA/TiO2 for Antibacterial Packaging

“…The detailed band assignment for the most representative vibrations is given in Table S2. Additionally, a full characterization of the PLA spectra in NIR region is described in Reference [22].…”

“…Films of ca. 2.0 g were obtained according to the protocol described in Reference [22]. A solution of 10% wt/vol of PLA in dichloromethane (CH 2 Cl 2 ) was mixed with a suspension of TiO 2 NPs in CH 2 Cl 2 (previously sonicated).…”

Classifying Degraded Three-Dimensionally Printed Polylactic Acid Specimens Using Artificial Neural Networks based on Fourier Transform Infrared Spectroscopy

“…Liu et al [13] employed thermogravimetry (TG)-FTIR to investigate the effects of PLA degradation with two additives, namely, starch and wood flour. Gonzalez et al [14] studied PLA/TiO2 nanocomposites by using FT-NIR spectra. Leroy et al [15] used FTIR to monitor PLA degradation in implantable medical devices.…”