The Research Of PLA/DBP Blending Membranes

Poly(lactic acid)(PLA) with high molecular weight is a kind of high performance biodegradable material. In comparison with other biodegradable materials, it has many advantages such as high strength, thermo plasticity, hydrophobicity, good fabric ability, biodegradability, availability from renewable resources and bioenvironmental compatibility. However, the conventional ring opening polymerization route to synthesize high molecular weight PLLA is too complex and expensive, so the application of PLLA is usually limited in the biomedical area. To reduce the production cost and widen the application area of PLLA, two methods were investigated in this paper. One method is to synthesize low molecular weight PLA-OH by direct condensation-polymerization. Another one is select di-butyl phthalate(DBP) as the second component and produce the PLA/DBP composites by solvent blending in the presence of compatibilizer.1. A direct polymerization of lactic acid and 1,4-butanediol was studied. Lactic acid was condensation-polymerized to hydroxyl-terminated prepolymer with low molecular weight. The structure of the resulting polymer was confirmed by IR and 'HNMR.2. PLA synthesized through ring-opening polymerization of intermediate lactide prepared from lactic acid. The influences of purification of lactide, temperature and time of polymerization on the molecular weight of PLA were discussed. This indirect method costs too much due to its complicated technology and low yield, but can get high molecular weight.3. The membranes of Poly(lactic acid) and DBP were prepared by solvent-blending and being flowed into films in the PLA/DBP ratios of 100/0, 90/10, 80/20, 70/30, respectively. It was concluded from scanning electronic microscope(SEM) that membrane is softer with DBP increased. From tensile testing, with the DBP component increasing, the flexibility of PLA/DBP membranes was enhanced, the brittleness of PLA was deceased.4. Blood compatibility of PLA/DBP membranes were tested. According the normal method, the result show that PLA/DBP membranes have good blood compatibility.5. The experiments of degradation of PLA/DBP membranes demonstrated from PH of solvent, weight of membrane and content of lactic acid in solvent.All of above results show that the PLA/DBP membrane is an excellent biodegradable material for environmental protection with good mechanical properties, good blood compatibility. DBP increased the softness of PLA.