Effect of UV irradiation on enzymatic degradation of cellulose acetate

Abstract

The effect of UV irradiation on enzymatic degradation of highly substituted cellulose acetate (CA) was investigated. The degradability of CA by cellulase decreased with increasing the degree of substitution (DS) of CA. Combination of the deacetylating enzyme (lipase or esterase) and cellulase did not promote the degradation of CA with DS 2.4. On the other hand, the UV-irradiated CAs that were suspended in the sterilized buffer and cellulase solution showed 23% and 60% of weight loss, respectively. UV irradiation resulted in the decrease of molecular weight of CA and did not affect DS. Observation by atomic force microscope confirmed that UV irradiation increased the surface area of CA film. Wash-out of depolymerized component from UV-irradiated CA film would increase the surface area and the contactability with cellulase. These results suggested that degradation of CA by cellulase would be positively influenced by UV irradiation under the natural environment.