- MOLECULAR PHYSICS Journal
- July 2017
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- Near infrared spectroscopy in the transmission mode was used to study the effect of the presence of TiO2 nanoparticles on the dynamics of Polylactic Acid (PLA) in PLA/TiO2 nanocomposites. The variation of IR absorbance of certain bands, the average energy of those absorptions (, cm-1) and two-dimensional Infrared (2D IR) correlation spectroscopy as a function of temperature and TiO2 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-TiO2 nanocomposites as a function of temperature, seem to point out the presence of specific interactions between the C = O group and TiO2 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.
- polymer dynamics; 2d-infrared correlation spectroscopy; polylactic acid (pla); tio2 nanoparticles