The band at 1460 cm -1 is characteristic for R-CH2-CH3 and -C-C-in rings, while the band at 1369 cm -1 reflects rocking vibrations of C-H in fatty acid chains of Priplast 1838. At 1302 and 1049 cm -1 , the presence of RCOOR' vibration in esters was detected, while the bands at 1236 cm -1 and 1168 cm -1 reflect the -C-O-stretching vibration and -C-O-C(=O) stretching vibration, respectively.