The Study On Synthesis Technology About Direct Preparation Of Poly(Lactic-Acid)

The paper first studied the synthesis of poly(lactic-acid) ( PLA ) by direct melt olycondensation in the material of lactic-acid and search for the influence by the facts such as kinds of catalysts, quantity of catalusts, polyondensation temperature and vacuum in the system. the reaction process was optimized by the change such like the time of wather deprive,the adjunction of antioxidant. Then we make the PLA which sunthesised to chain-extentioned by use the way of end group termination,and studied the influence of the molecular of prepolymer, the time and the temperature of chain-extention, the ratio of acid alcohol and we systematically to studied the influence of all these factors.finally had the best chain-extention process is : first let the prepolymer toend group termination with 1,4– butanediol(BDO) about 2 hours,then added the Toluene-2 ,4– diisocyanate in the rate of nNCO:nOH=1:1,which reacted 10minutes in the 100Pa vacuum.Paper also studied the structure, thermal performance and crystallization performance of PLA and poly(lactic acid) based carbamate were characterized by FT-IR, DSC and WAXD,and studied the PLA filature technic by Melt Index Instrument.