If you increase chitosan content then absorption band around 240 nm for all curves will be slightly shifted towards shorter wavelengths in UV range due to crystal structure of polymer...For FTIR, wavenumbers will be in between 962 to 3380/cm..

You may observe the band at 218 nm in the UV spectra due to n to pie star transition.. Another absorption will be observed at about 273–280 nm and it may be attributed to pie to pie star which comes from unsaturated bonds mainly carbonyl. The increase in this with increasing chitosan content may be attributed to the interaction between chitosan and the polymers blend, and hence complexation. The intensity increases with increasing chitosan content, and this indicates that chitosan can be used as an optical application if you are using this blend for optical purpose..

Apart from this, read these references:

1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4003268/

2) www.worldscientific.com/doi/pdf/10.1142/S2010135X14500337

sir,...my films are transparent, and the ration of blend is fixed(50-50)..i am getting only one peak at around 300 nm...i am attaching the graph..plz suggest me,,..i want to study optical property of my transparent samples..i want to calculate Eg and refractive index....is it possible to calculate?

ok...thnq peter sir, can i tell that the absorption in uv region is high ..?can be applicable for packaging application.through this graph..plz suggest me..iam thankfull