抄録
Biodegradable plastics, such as poly(L-lactic acid)(PLLA), poly(ε-caprolactone)(PCL)and poly(1,4-butylene suc-cinate)(PBS), degrade in natural environments and composting facilities. We have been developing porous mem-branes of biodegradable plastics to reduce the wastes formed in filtration processes in food and biochemical indus-tries. Microporous membranes of PLLA, PCL and PCL-PLLA-blends were preparedvia thermally induced phase sep-aration. The hydraulic resistance and pore size of the membranes were evaluated by filtration of water and a suspen-sion of yeast cells (6μm), respectively. The PLLA membrane had high permeation resistance (low permeability)although it retained yeast cells on the membrane. The PCL membrane passed the yeast cells although it had highpermeability. Thus we prepared microporous membranes of polymer blend of the two biodegradable plastics to yieldhigh permeability and high cell retention. The resistance of PCL-PLLA-blend (4:1)membrane was as low as that ofthe PCL membrane. The polymer blend membrane retained yeast cells in a manner of depth filtration, which allowedfor fast filtration. Microporous membranes of PBS were prepared from PBS-chloroform solutions via immersion pre-cipitation method with a coagulation bath of methanol. Membranes prepared from 10% PBS solutions pre-incubatedat 47.5℃show a permeation resistance of 1011m–1and a retention of the bacterial cells (0.7φ×2.5μm)of 99%. Themicroporous membranes of biodegradable plastics will be helpful as prefilters to eliminate the waste of filter and filteraids in food and biochemical industries.
