This notable red shift of
wavenumber corresponding to the hydroxyl group in the HLS/PVA system is up to = 133 cm−1, suggesting strong hydrogen bond formed between them [32].
In addition, the typical band at 1142.5 cm−1 in the difference spectra is associated with the C-C
stretching vibration in the crystal which is coupled with the C-O
stretching or to the O-C-C symmetric stretching vibration.
This band becomes weaker with higher HLS amount in the blends,
indicating destroy of PVA crystallinity which could be proved by
the DSC analysis results.