Physical properties of microporous membranes prepared by hydrolyzing cellulose/soy protein blends

Microporous membranes (CS1-n) were prepared by blending cellulose and soy protein isolate (SPI) in 6 wt.% NaOH/5 wt.% thiourea aqueous solution. The membranes CS1-n were hydrolyzed with 5 wt.% NaOH aqueous solution to obtain membranes CS2-n. The structure and properties of the membranes were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), the flow rate method, and tensile testing. The blend membranes CS1-n exhibited mesh structure woven by SPI and cellulose, and the membranes CS2-n possess microporous structure as a result of the removal of SPI during the NaOH-hydrolysis process. The apparent pore size (2re) measured with SEM, the mean pore size (2rf) obtained by the flow rate method, and the water ultrafiltration rate (UFR) of the CS1-n and CS2-n membranes increased with an increase in SPI content, and are higher than those of the pure cellulose membrane and previous membranes. The values of 2rf (47.7–77.2 nm) and UFR (28–53.5 mL h−1 m−2 mmHg−1) of the microporous membranes CS2-n are higher than those of the corresponding membranes CS1-n, because of removing of most of SPI by NaOH-treatment. The microporous membranes also kept high tensile strength in both dry and wet states. In addition, the membranes CS2-n containing a small amount of SPI are suitable for the culture of Vero cells. Therefore, the membranes could be used as candidates for application in separation technology and biomedical fields.