聚乳酸/四针状氧化锌晶须非等温冷结晶行为的研究

NONISOTHERMAL COLD CRYSTALLIZATION BEHAVIORS OF PLA/TETRAPOD-LIKE ZINC OXIDE WHISKERS

采用熔融共混法制备了聚乳酸（PLA）／四针状氧化锌晶须（T-ZnOw）。用差示扫描量热仪研究了PJJA及PLA／T—ZnOw的非等温冷结晶行为；用Jeziomy法和Mo法对其非等温冷结晶动力学进行了分析研究，并计算了相关的结晶动力学参数。结果表明，Jeziorny法和Mo法均能很好地描述PLA及PLA／T-ZnOw的非等温冷结晶过程，且结果一致。Jeziomy法分析表明，初次结晶阶段PLA及PLA／T—ZnOw的Avrami指数n．值范围分别为4．22～5．43和3．11～4．80，而二次结晶阶段的Avrami指数n，值范围分别为3．10～4．66和2．69～5．57，说明T—ZnOw的加入改变了PLA的成核和晶体生长规律。Mo法分析表明，在相同的X（t）下，PLA／T—ZnOw的F（T）值整体大于PLA，T—ZnOw的加入降低了PLA的结晶速率。偏光显微镜观察结果显示，随着T—ZnOw的加入，PLA球晶尺寸减小，数目增多。

The polylactic acid/tetrapod-like zinc oxide whiskers（PLA/T-ZnOw） was prepared by melt blending. The noniso- thermal cold crystallization behaviors of PLA and PLA/T-ZnOw were investigated by differential scanning calorimetry （ DSC ）. The method of Jeziorny and Mo were employed to analyze the nonisothermal cold crystallization kinetics for PLA and PLA/T-ZnOw, and the related kinetic parameters were obtained. The results showed that both the two methods could well describe the nonisothermal cold crys- tallization process of PLA and PLA/T-ZnOw composites. The calculated Avrami index value n~ of PLA and PLA/T-ZnOw was 4.22 5.43 and 3.11 - 4.80 respectively at primary crystallization stage, while n2 was 3.10 - 4.66 and 2.69 - 5.57 respectively at seconda- ry crystallization stage, which indicated that the crystal growth pattern of PLA/T-ZnOw was changed because of the addition of T- ZnOw. The results of the method Mo showed that most of the values F（T） of PLA/T-ZnOw were greater than those of PLA at the same X（ t）, which suggested that the crystal rate decreased with the addition of T-ZnOw. The polarized optical microscopy was employed to observe the crystal morphology of PLA/T-ZnOw composites. The results of polarizing microscope showed that the crystal size of PLA decreased while the number of nucleus grew up with the addition of T-ZnOw, which indicated that T-ZnOw could promote the nucleating process of PLA.