Polylactide Film Crystal Morphology And Crystal Dynamics Research

Polylactic acid (PLA) is a widely used polymer materials. It has good biodegradability and biocompatibility and easy process. PLA in crystal chain zone arranged neat closely, more perfect, and to improve the crystallization mechanical properties and delay the degradation speed, half crystal sexual PLA crystallization rate slowly, limiting its application. Another high crystallinity, the PLA hard and brittle degradation time too long. Therefore, understanding the PLA's crystallization behavior, deeply discuss the factors affect PLA crystallization behavior, benefit from the microscopic control of its structure, so as to improve the material processing and using performance and expand their application scope.Firstly, using polarizing microscope (POM), atomic force microscope (AFM), transmission electron microscope (TEM) and X-ray diffraction PLLA are studied film norbornene-type homopolymers crystallization form, the results of the study indicate that: low temperature, temperature more likely to form nuclei in 90℃, the highest number PLLA crystals, more than 90℃later, with the crystallization temperature rising, crystal troop buildup. Crystal℃growth in most perfect 131 before, on the temperature increasing perfect degree, more than 131℃later perfect degree instead decline. PLLA film has rich variety of crystalline form, such as short sticks, chrysanthemum petals, fiber bundle, .globose, belt, etc. This and solution concentration, the crystallization temperature, crystallization time, basement, solvents and other factors has the very big relations.This paper also studies the isothermal crystallization kinetics blend of PLLA/PCL, the research shows that:in PLLA/PCL isothermal crystallization process, Avrami index n, which demonstrates the hundredth 2 PLLA and blend of PCL by out-of-phase nucleation two-dimension plane spherulite growth mode. And found that as the crystallization temperature decreased, which tmax t1/2, the values are reduced, this suggests that crystallization rate in the lower temperature and speed up crystallization.