Abstract: With alkali lignin(L) and polyvinyl alcohol(PVA) as primary material, glutaraldehyde as crosslinker, alkali lignin/PVA cross-linked reaction film was prepared by casting. The process conditions were determined by single-factor test. The reaction film was characterized by FT-IR and SEM. The optical performance of reaction films was investigated by UV-Vis spectrophotometer. The results showed that when mass ration of alkali ligini/PVA was 1/10, glutaraldehyde content was 1.67 % (w/w) of the dry matter. The reaction film had good optical performance. Crosslinking reaction took place and the structure of ether bond was formed between alkali lignin and PVA. The surface of reaction films was smooth. After adding alkali lignin, UV absorbance of the reaction films was increased nearly 90% and in the visible area transmissivity was decreased about 40%. Alkali lignin had a great influence on films of absorbance and transmissivity. The more glutaraldehyde, the higher transmissivity of the reaction films in the visible area. The influence of glutaraldehyde on UV absorbance of the reaction films was not obvious. The UV absorbance is influenced mainly by alkali lignin. Alkali lignin/PVA can be used as a good ultraviolet absorption material.

Key words: alkali lignin, polyvinyl alcohol, crosslinking, optical properties