Besides, the new band at 1403cm−1 region was the signature for a Schiff base adduct analogous to the deformation of C—H (Poon, Wilson, & Headley, 2014).
Evidences near 2720cm−1 of vs (C—H) and 1720 cm−1 of vs (C O)associated with free aldehydic group had not been found and consequently there was no or slight residual cross-linker (Monteiro & Airoldi, 1999).