聚对苯二甲酸乙二醇酯-双酚A型聚碳酸酯共混体系中聚合物伸直链晶体的形态分析

利用扫描电子显微镜(SEM)和原子力显微镜(AFM)等表征手段,研究了聚对苯二甲酸乙二醇酯-双酚A型聚碳酸酯(PET-PC)共混物的高压结晶样品。研究发现共混体系中存在具备不同形态特征的伸直链晶体,其中包括楔形晶体、弯曲晶体以及楔形弯曲晶体。通过对这些晶体的形态观察,揭示出体系中大尺寸聚酯伸直链单晶体的增厚生长首先要经历形成折叠链晶核的成核阶段,然后才是在酯交换反应和链滑移扩散两种机制共同作用下的等温增厚的链伸展过程。有助于深入理解PET-PC共混物中伸直链单晶体生长过程的本质因素,以便在类似聚合物体系中合成大尺寸的同类晶体。

Morphology Investigation of the Extended-Chain Crystals in High-Pressure Crystallized Poly (Ethylene Terephthalate)-(Bisphenol-A) Polycarbonate Blends

Morphologies of extended- chain crystals with different characteristics, i.e. wedge-shaped crystals, bent crystals and wedge- shaped bent crystals, were disclosed with scanning electron microscopy (SEM) and atomic force microscope (AFM) in the high-pressure crystallized poly (ethylene terephthalate)/bisphenol-A polycarbonate (PET-PC) blends. The observations revealed that the thickening growth for the large polyester extended-chain single crystals should first undergo the nucleation step leading to the folded-chain nuclei, and then, the chain extension process which is an isothermal thickening resulting from transesterification and sliding diffusion. The morphological structures shed light on the fundamental nature of the large single crystals in the blends, which may be instructive to grow such large crystals in similar polymer systems.