| Polylactic acid (PLA) is an excellent biodegradable material, which can be used in medical and commodity field, such as osteogenic material, surgical sutures, drug delivery vehicles,biodegradable plastics and fiber products. In this paper, lactide acid was synthesized by (D,L) lactic acid, which was used to prepare polylactic acid (PLA). Polycaprolactone (PCL) was used to change property of poly(D,L) lactic acid for controllable degradation. And polylactic acid microspheres were prepared by solvent evaporation method.(1) Under some conditions,Lactide acid can be synthesized by (D,L) lactic acid. These conditions include the amount of catalyst (ZnO) of 4.0 g, thedehydration time of 3h, dehydration temperature of 130 ?, the depolymerization temperature of 240 ?, the lactide acid and was purified by ethylacetate. Then PLA was prepared by ring-opening polymerization method. Orthogonal experiment showed the optimal conditions:polymerization temperature of 170 ??the polymerization time of 4 h and the catalyst concentration of 0.06 g/mL. And the PLA was characterized by DSC, 1H-NMR and IR.(2) The polylactic acid microspheres was prepared by solvent evaporation method. And the best preparation process was found:PLA concentration of 6.0% g/ mL, PVA concentration of 1.0% g/mL, volume ratio of 1:2, stirring speed of 1000 r/min. The SEM photographs show that the PLA microspheres with uniform size, about 20 ?m, which have uneven surface and microporous structure.(3) Polycaprolactone (PCL)/polylactic acid (PLA) blend was prepared by melt mixing and characterized by DSC,'H-NMR and IR. The result showed that the coblend with compatibility agent (PLA-co-PCL) are more smooth than the direct coblend, and that the ester group, the methyl, the methylene and the tertiary methyl were found in the 1H-NMR and IR spectroscopy. The degradation test on different PCL/PLA ratio of coblend was carried out and the result shows that the higher the proportion of PCL, the slower the degradation of coblend. |
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