In WNP, the maximum absorption of the O H stretching was located at 3333 cm−1. After the dissolution and subsequent regeneration, the O H stretching peak shifted to higher wave number, 3351 cm−1for Film and 3353 cm−1 for f-Film. Accordingly, the C H stretching peak at 2896 cm−1 for WNP shifted to lower wave number, 2888 cm−1for Film and 2890 cm−1for f-Film,