STRUCTURE AND FILTRATION PERFORMANCES OF IMPROVED CUPRAMMONIUM REGENERATED CELLULOSE HOLLOW FIBER (IMPROVED BMM HOLLOW FIBER) FOR VIRUS REMOVAL

To get higher performances of virus removability and permeability of protein than those of the previous cuprammonium regenerated cellulose hollow fiber (referred to as BMM) novel spinning coditions such as minimerized tension loaded on a fiber in addition to high accurate control of temperature and composition were employed (the novel BMM hollow fiber thus obtained is referred to as i-BMM). Comprehensive analysis of the pore structure of i-BMM using electron microscope and its filtration characteristics concerning to virus removability and protein permeability indicated that (1) the degree of orientation of the cellulosic substrate and "voids" in i-BMM to the direction of the fiber axis decreased comparied with that of BMM and this led to the disappearance of the breakage of the cellulosic wall between neighbouring voids, (2) the size of the capillary of i-BMM was larger than that of BMM, (3) the virus removability of i-BMM for Japanese encephalitis virus was about 10(3) times BMM when the comparison was made under the same mean pore size. These indicate that the existence probability of "voids" linking side by side and penetrating the membrane from the inner to the outer surface decreased for i-BMM and this is the reason i-BMM is superior to BMM in virus removal.