Dielectric properties of cellulose irradiated with gamma-rays

The effects of gamma radiation from cobalt-60 on the dielectric properties of dry cellulose were investigated. Cole-Cole's circular are law could be satisfactorily applied to the data obtained and the parameters of the circular arc, (epsilon0-epsilon sub(infinity)) and β, were determined. Up to a dosage of 1 x 107 rad, no significant change in the value of these parameters took place. Irradiation to a dosage of 3 x 107 rad produced a slight increase in the value of (epsilon0- sub(infinity)) but little change in the degree of crystallinity. This would suggest that the number of CH2OH group contributing to the orientation increased mainly in the amorphous region. At irradiation levels in excess of 3 x 107 rad definite reduction in the degree of crystallinity was observed. And the value of (epsilon0-epsilonsub(infinity)) reached a maximum at around 1 x 108 rad, and this would suggest that the number of CH2OH group contributing to the orientation increased both in the amorphous and the crystalline regions. Irradiation above 1 x 108 rad induced a rapid decrease in the value of β, (epsilon0-epsilon sub(infinity)) and the degree of crystallinity. This would suggest that the number of CH2OH group decreased as a result of oxidization. On the other hand, by irradiation another dielectric relaxation process occurred in low frequency range at room temperature, and it was estimated that this process was probably due to the orientation of H2O adsorbed to CHO and/or COOH groups. (auth.)