Biodegradable Polylactic Acid Materials Research

In the circumstance, the catabolites of polylactide are CO2 and H2O which can solve the environmental pollution of petroleum polymer. As an important biomedical polymer materials , polylactide has the excellent biocompatibility which were used for absorbable suture, bone internal fixation, drug controlled release, tissue engineering etc. so polylactide is the at present.In this paper, L-lactide and D,L-lactide were prepared from lactic acid, glycolide was prepared form glycolic acid. Using the different hydrolysis speed in the water between the meso-lactide and the other lactides, high pure L-lactide and D,L-lactide were obtained by water bath and two times recrystallization. The moisture of the pure lactide was under 0.006% and the optical purity was 99.88%. Comparing to the recrystallization method, the yield of lactide purified by water bath purifying method was increased by 10%. Glycolide was obtained with two different crystal structure of a and (3 under different temperature evaporating the dissolvent.Polylactide and the copolymer of lactide and glycolide were obtained by ring-opening polymerization with Sn(Oct)2 as the catalyst. The effect of catalyst concentration and reaction temperature on the viscosity-average molecular weight of the polymer was discussed. The highest viscosity-average molecular weight has exceeded 55 l04 The structure, purity, physical chemistry properties of cyclic diester and molecular weight of polymer were confirmed through the fusion point,ABSTRACTcontent of carboxyl group, optical rotation, viscosity, moisture, IR spectra, 'H-NMR, GC/MS, X-ray of cyclic diester. The chain segment structure of poly(L-lactide) and poly(D,L-lactide) were confirmed through Homonuclear decoupling 'H-NMR. The bending strength of polymers were 80~160MPa, the shear strength were 60~110MPa; the porosity of porous foam materials was 75% and pore size with diameters was in the range of 200 to 400um. The result show that the polymer are fit to manufacture bone internal fixation and bone tissue scaffold materials.