Li Deling, Luo Congcong, Zhou Jun, Dong Liming, Chen Ying, Liu Guangtian, Qiao Shuyun
College of Materials and Chemical Engineering, Xuzhou University of Technology, Xuzhou 221018, China.
School of Environment and Chemical Engineering, Yanshan University, Qinhuangdao 066004, China.
Polymers (Basel). 2023 Mar 22;15(6):1579. doi: 10.3390/polym15061579.
Corn starch was plasticized by glycerol suspension in a twin-screw extruder, in which the glycerol suspension was the pre-dispersion mixture of glycerol with nano-SiO. Polylactide (PLA)/thermoplastic starch/SiO composites were obtained through melt-blending of PLA with thermoplastic starch/SiO in a twin-screw extruder. The nonisothermal crystallization behavior of PLA in the composites was investigated by differential scanning calorimetry. An interface of PLA with thermoplastic starch was proven to exist in the composites, and its interfacial bonding characteristics were analyzed. The interfacial binding energy stemming from PLA with thermoplastic starch exerts a significant influence on the segmental mobility of PLA at the interface. The segmental mobility of PLA is gradually improved by increasing interfacial binding energy, and consequently, the relative crystallinity on the interface exhibits progressive promotion. The Jeziorny model could well describe the primary crystallization of PLA in the composites. The extracted Avrami exponents based on the Jeziorny model indicate that the primary crystallization of PLA follows heterogeneous nucleation and three-dimensional growth. This study has revealed the intrinsic effect of the interfacial segmental mobility on the nonisothermal crystallization behavior of PLA in composites, which is of technological significance for its blow molding.
玉米淀粉在双螺杆挤出机中通过甘油悬浮液进行增塑，其中甘油悬浮液是甘油与纳米二氧化硅的预分散混合物。聚乳酸（PLA）/热塑性淀粉/二氧化硅复合材料通过在双螺杆挤出机中将PLA与热塑性淀粉/二氧化硅进行熔融共混而制得。采用差示扫描量热法研究了复合材料中PLA的非等温结晶行为。证实了复合材料中存在PLA与热塑性淀粉的界面，并对其界面结合特性进行了分析。PLA与热塑性淀粉产生的界面结合能对界面处PLA的链段运动性有显著影响。通过增加界面结合能，PLA的链段运动性逐渐提高，因此，界面处的相对结晶度呈现出逐步提升的趋势。Jeziorny模型能够很好地描述复合材料中PLA的初级结晶过程。基于Jeziorny模型提取的Avrami指数表明，PLA的初级结晶遵循异相成核和三维生长。本研究揭示了界面链段运动性对复合材料中PLA非等温结晶行为的内在影响，这对其吹塑成型具有技术意义。
