Far-IR spectra of neat CER matrix and the CER/amino-MMT nanocomposites. Numbers indicate amino-MMT contents. (a) Changing of the spectrum due to introducing 0.05 wt. % amino-MMT; (b) the absorption band of ring vibrations (librations), and (c) the absorption band of skeletal torsional vibrations which is practically identical for neat matrix and the nanocomposites with 0.05, 0.5, and 1 wt. % MMT.