高耐热PLLA/PDLA共混物的热性能和结晶结构研究  

CRYSTALLIZATION STRUCTURES AND THERMAL PROPERTIES OF HIGH HEAT-RESISTANCE PLLA/PDLA BLENDS

作　　者：陈璐[1] 唐颂超[1] 夏季[1] 蒲文亮[1] 李瑞[1] 

机构地区：[1]华东理工大学材料科学与工程学院上海市先进聚合物材料重点实验室,上海200237

出　　处：《高分子学报》2013年第8期1006-1012,共7页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号51173041);国家科技支撑计划(项目号2012BAD32B01)资助项目

摘　　要：通过熔融共混法制备了一系列等比例聚左旋乳酸(PLLA)/聚右旋乳酸(PDLA)共混试样,采用差示扫描量热法(DSC)、核磁共振(13C-NMR)及广角X射线衍射(WAXD)等方法对共混产物进行了表征和研究分析.结果表明,等比例PLLA和PDLA熔融共混生成了立构复合物(stereocomplex,sc),同时部分均聚物发生酯交换反应,生成了立体嵌段物(stereoblock,sb),从而在DSC升温曲线上sc晶体处出现特殊的熔融双峰现象;随着熔融共混温度升高,sc晶体的生成率和结晶度逐渐下降;聚乳酸立构复合物的加工稳定性较好,二次加工后,sc晶体熔点基本不变,生成率和结晶度提高;由于sc晶体的存在,PLLA/PDLA共混物的耐热性能提高,退火热处理后耐热性能得到进一步提高.这对于开发高耐热聚乳酸及其加工应用具有重要的应用价值.A series of equimolar blends of poly(L-lactic acid)/poly(D-lactic acid)(PLLA/PDLA) were prepared by melt mixing and the blends were investigated by means of differential scanning calorimetry(DSC),nuclear magnetic resonance(13C-NMR),wide angle X-ray diffraction(WAXD),etc.It was found that when the blending temperature was 210 ℃,the stereocomplex(sc) formed from equimolar PLLA/PDLA blends exhibited a high melting temperature at 229 ℃ and showed 98.1% crystallinity degree.As for the sample after isothermal annealing up to 120 ℃,the Vicat softening temperature approached to 126.4 ℃.It was indicated that double melting endotherms were characteristic for the sc crystals in the DSC thermograms,where formation of the stereoblock(sb) occured at high processing temperatures.The high-temperature-side(230 ℃) endotherm and the low-temperature-side(210 ℃) endotherm resulted from the melting of sc and sb crystals respectively.As the blending temperature increased,the high-temperature-side endotherm was reduced and the low-temperature-side endotherm was emphasized.The relative amounts and crystallinity degree of sc crystals decreased significantly with the increase of blending temperature.The sc-PLA had good processing stability.The melting temperature of sc crystals stayed constantly after second blending.Moreover,the relative amounts of sc crystals increased slightly.The PLLA/PDLA blends composed of networks of sc might be applicable to the heat-resistant materials,and this paper provided a new method of improving thermal stability and processing property of PLA.

关 键 词：聚乳酸 立构复合物 立体嵌段物 熔融共混 

分 类 号：O631.3[理学—高分子化学]