Synthesis And Characterization Of Biodegradable PDLLA

The macromolecule poly-lactic acid ( PDLLA ) since there being the good compatibility and degradable, Hence widely having been used to the absorbing operation thread, burn cover and internal fixation of bone fracture. The second operation suffering may be avoided as filling the stuff inner place the fracture admittedly. But causing to poly-DL- lactide initial stage mechanics intensity fit the stuff demand admittedly, the key is how to improve the molecular weight.The preparing means of poly-lactic acid chiefly have immediate-condensation polymerization and the ring-open polymerization. Compared with these two method, The molecular weight by immediate-condensation polymerization is low but also the molecular weight distribute broadly, The stuff can not fit some mechanics performance admittedly, so, preparing high molecular weight PDLLA in common use is that the ring-open polymerization, that is, synthesis lactide by lactic acid and ring-open polymerization by lactide.Preparing degradable PDLLA by D,L-lactic acid in this paper. That reactchiefly to be divided into two steps--Preparing lactide and Ring-openpolymerization. First of the step is in the condition of vacuum and the action ofcatalytic agent--ZnO, Obtaining PDLLA by ring-opening polymerizationwhich initiated with Sn(Oct)2.In the first process, The apparatus modification react by means of adjust instrument, Resolve lactide jam, Moreover decrease much loss; Research the catalytic agent the amount to be used, Dehydration temperature, Dehydration time, Dehydration amount along with depolymerization temperature, depolymerization time which affect the reaction, Getting the optimum technology term of the reaction. Characterized lactide and purified lactide. Research in the purification process infrared spectrum and the melting point alternation. Discussing initiator the amount to be used, polymerization temperature, polymerization time and vacuum and so on that affect the molecular weight. According to the research, preparing the high-molecular weight lactic acid by means of the ring-open polymerization is feasible. The main parameters are: I/M about 0.03%, polymerization temperature 140℃, polymerization time 48h, vacuum 0.05mmHg.