Studying the photodegradation of ethylcellulose and methylcellulose in the presence and absence of benzophenone (BPh)

Abstract

The induced photodegradation of ethylcellulose (EC) and

methylcellulose (MC) films in air was investigated in the presence and

absence of benzophenone (BPh) (photosensitizer) by accelerated

weathering tester. The addition of (0.2wt %) of benzophenone (BPh) to

cellulose derivatives films (25µm in thickness) enhanced the

photodegradation of the ethylcellulose (EC) more than methylcellulose

(MC) films.The photodegradation rate was followed by increase in

carbonyl absorbance of polymers and decomposition rate constant (k _d ) of

benzophenone in polymers using I.R and U.V­Vis. spectra respectively.

According to the kinetic data and spectra results, the induced

photodegradation mechanisms of cellulose derivatives films were

suggested under the experimental conditions employed using

u.v.­radiation at λ = 313 nm , light intensity 3.49*10 ­5 einsteins.dm ­3 .S ­1 at

temperature 45 o C.