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将聚L-乳酸(PLLA)熔化非等温熔融结晶,采用DSC、POM、SEM等技术研究了降温速率对PLLA的热行为和形貌的影响.PLLA在低降温速率(2℃·min~(-1))下的结晶在118℃伴随有结晶机制的转变.玻璃化温度和结晶度随着降温速率的降低而增大.随着降温速率的降低,球晶尺寸增大,当降温速率为10℃·min~(-1)时,PLLA为无定型材料.采用模压成型的方法并控制降温速率制备了具有球晶结构的条状PLLA生物材料,与高降温速率下制备的PLLA相比,低降温速率下获得的具有球晶结构的PLLA材料的断面更光滑和致密,但脆性增强.
The effects of cooling rate on the thermal behavior and morphology of PLLA were studied by DSC, POM and SEM techniques.PLLA was used in low temperature cooling rate (2 ℃ · min ~ (-)) 1) crystallizes at 118 ℃ with the change of crystallization mechanism.The glass transition temperature and crystallinity increase with the decrease of the cooling rate.With the decrease of the cooling rate, the spherulite size increases, when the cooling rate is 10 PLLA is an amorphous material, and PLLA is an amorphous material at a temperature of -50 ℃ · min ~ (-1), and the spheroidal PLLA biomaterials with spherulitic structure were prepared by compression molding and controlled cooling rate.Compared with PLLA prepared at high cooling rate The PLLA material with spherulitic structure obtained at the cooling rate has a smoother and more dense cross-section but an enhanced brittleness.