Effect of electron beam irradiation on pore structure of ethyl cellulose membranes

Abstract

In this paper, ethyl cellulose (EC) membranes were successfully prepared by phase conversion method, and irradiated by electron beam. The as prepared and irradiated EC membranes were characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC). The EIS test results show that the resistance of EC membrane increases obviously after irradiation, implying it is more difficult for ions permeation. SEM suggests that the irradiation might shrink the pores of EC membranes might be smaller after irradiation. PALS results indicate that the o-Ps lifetime decreases with the irradiation dose, while the o-Ps intensity increases. DSC results indicate the crystallinity of EC increases with the irradiation dose. All the above results imply the irradiation induces the chain scission and rearrangement of chain segment. Thus, the large pores were divided into more small pores, and the crystallinity increases with the increase of irradiation dose. Moreover, there is an inverse relationship between the membrane resistance obtained from EIS and the square of free volume radius calculated from PALS results, which suggests the free volume holes play an important role in ion permeation.