采用差示扫描量热法测试了聚羟基丁酸酯(PHB)的结晶温度和熔融温度,采用偏光显微镜探讨了结晶温度和结晶时间对PHB结晶形态的影响及环带球晶形成机理。PHB在高于100℃易形成环带球晶,环带间距随着结晶温度的升高而降低.且低温下形成的球晶数目明显比高温多;结晶时间只能改变晶体尺寸,并没有改变结晶形态:环带是片晶沿晶轴方向作周期性扭曲的结果;PHB球晶中的裂缝主要是由于片晶在“侧立”取向扭曲成“平躺”取向时产生的。
Crystallization temperature and melt temperature of polyhydroxybutyrate (PHB) were tested by differential scanning calorimetry (DSC). The effects of the crystallization temperature and crystallization timeon crystalline morphology and formation mechanism of the banded spherulite were studied by means of polarized light microscope (PLM). PHB was easy to form banded spherulite when the temperature was above 100℃. The band spacing decreased as the crystallization temperature increased, and the number of the spherulite formed at low temperature was significantly more than at high temperature. The change of thecrystallization time only altered the dimension of the crystal, but did not affect the crystalline morphology. The band was the consequence caused by the periodic distortions of the lamellae along the crystal axis. Thecracks in the PHB spherulite were generated when the lamellae distorted from the edge-on orientation to the flat-on orientation.