聚(L-丙交酯)/聚(DL-丙交酯)的结晶性能及相溶性

用共溶液沉淀法制备了聚 (L 丙交酯 ) 聚 (DL 丙交酯 )共混物 (PLLA PDLLA) ,然后用成纤模压法压制成3 2mm的棒材 .用差示扫描量热法研究了共混物的结晶性能和相溶性 .结果表明 ,PLLA组分在共溶液沉淀过程中可生成结晶 ,共混物中PDLLA含量直到 30 %时 ,PLLA组分的结晶熔融温度和结晶度与纯PLLA相同 ,但PDLLA含量为 5 0 %时 ,PLLA组分的结晶熔融温度和结晶度明显下降 .由于加工成型条件的不一致性 ,共混物棒材中的PLLA组分的结晶熔融温度和结晶度呈较大的分散性 .共混物从熔体降温 ,在其后的升温DSC扫描中出现分别相应于PDLLA和PLLA的玻璃化转变 ,表明PDLLA与未结晶的PLLA形成的非晶相是不相溶的

THE CRYSTALLIZATION AND MISCIBILITY OF POLY(L-LACTIDE)/POLY(DL-LACTIDE) BLENDS

Poly( L lactide)/poly (DL lactide)(PLLA/PDLLA) blends were prepared by co solution precipitation.They were molded into  3.2?mm rods by a method of fibrillated compression.The crystallization and miscibility of the blends were studied using differential scanning calorimetry(DSC).The results showed that the PLLA component can crystallize in the process of co solution precipitation.The melting temperature( T m) and crystallinity ( X c) of PLLA component are identical with those of the pure PLLA until the content of PDLLA in the blends up to 30%; however, they are decreased obviously for the blend containing 50% PDLLA.The T m and X c of the PLLA component in the rods scattered significantly and this may be attributed to their inconsistency in preparation. It was found that two glass transitions corresponding respectively to PDLLA and PLLA occurred in DSC heating scannings of the blends. This may indicate that PDLLA and the non crystalline PLLA in the blends are immiscible.