论文部分内容阅读
以L-乳酸单体为原料,采用复合催化剂通过直接熔融法合成低聚左旋聚乳酸(PLLA),然后分段控温进行固相缩聚(SSP)。对固相缩聚的工艺条件进行了详细的研究。采用粘度法和凝胶渗透色谱法(GPC)对固相缩聚产物PLLA的特性粘数([η])和分子量进行了表征。用差示扫描量热(DSC)研究了固相缩聚产物的熔融行为和结晶度。结果表明:绝对压力80Pa下,先在105℃下结晶2.5h,再升温至145℃反应35h,得到聚乳酸的重均分子量为42.6万,达到固相缩聚反应前的36倍;熔点达189.6℃,结晶度为69.25%,高分子量聚乳酸的成功制备为其工业化生产的新方法提供了方向。
L-lactic acid monomer was used as raw material to synthesize oligo-L-PLLA by the direct melting method with composite catalyst, and then the temperature was controlled by segmented temperature to carry out solid phase polycondensation (SSP). The solid phase polycondensation process conditions were studied in detail. The intrinsic viscosity ([η]) and molecular weight of solid phase polycondensation product PLLA were characterized by viscosity method and gel permeation chromatography (GPC). The melting behavior and crystallinity of the solid state polycondensation product were investigated by differential scanning calorimetry (DSC). The results showed that the weight average molecular weight of polylactic acid was 426,000 and reached 36 times before the solid state polycondensation reaction at the absolute pressure of 80 Pa after 2.5h crystallization at 105 ℃ and 35h reaction at 145 ℃. The melting point reached 189.6 ℃ , The crystallinity is 69.25%. The successful preparation of high molecular weight polylactic acid provides a new direction for its industrialized production.