Study And Preparation Of Poly(Ethylene Terephthalate) /Vermiculite Nanocomposites

Nanomaterials have drawn much attention in recent years due to their special properties, and polymer/layered silicate nanocomposites have become the research hotspots. In the late 1980s, Okada et. al. reported PA6/layered silicate nanocomposites, which had so unique properties that caused wide concern for researchers at home and abroad. Now, the research on polymer/layered silicate nanocomposites mainly focuses on polymer/montmorillonite nanocomposites, and some products have realized industrialization. However, there are few reports on the polymer/vermiculite nanocomposites.This thesis used dimethyl terephthalate(DMT), ethylene glycol(EG) and vermiculite as raw material, prepared polyethylene terephthalate (PET) /vermiculite nanocomposites via transesterification method, and characterized the products by XRD, TEM, SEM, DSC and oxygen index instrument. The research purpose is to improve the properties of PET, especially the crystallization rate and flame retardant property.The main content of this thesis is as follows. Vermiculite was purified and organized. Ethylene terephthalate was prepared using DMT and EG by transesterification method. Then ethylene terephthalate, as intercalation reagent, underwent the intercalation reaction with organic vermiculite. After that, catalyst was added to enable the ethylene terephthalate/vermiculite composites process condensation polymerization. Finally, PET/vermiculite nanocomposites were prepared. XRD,TEM,SEM and DSC were utilized to study the synthesis method and reaction condition, indicating that exfoliated PET/vermiculite nanocomposites were prepared under the optimized condition: DMT: EG(mol.)=1: 1.8; organic vermiculite dosage 3%; the homogeneous mixture of organic vermiculite, EG and catalyst reacted with fused DMT for 2～3h at 220℃～230℃, then underwent pre-condensation polymerization for 3h at 230℃～245℃and condensation polymerization for 3h at 265℃～278℃. The results by DSC and oxygen index instrument showed that the crystallization rate of PET/vermiculite nanocomposites was improved from Tc=200.39℃of PET to Tc=206.42℃of PET/vermiculite nanocomposites, the temperature of crystallization peak shifted to higher temperature, and oxygen index of PET/vermiculite nanocomposites increased from 21.5% to 29.4%, indicating theenhancement of flame retardant property.