The Preparation And Characterization Of High-barrier PET/MMT Nanocomposites

Poly (ethylene terephthalate) is one of the most important polyester, commonlywas known as the polyester resin, was widely used in fibers, biaxially stretched filma, polyester bottles and a variety of packaging containers. The property of highbarrier has been concered by people and developed rapidly in the process ofapplication as the main function of the PET packaging materials.In this paper, the two methods was used to improve the barrier properties ofPET, respectively,(a) The modified montmorillonite was added to PET andprepared PET/MMT nanocomposites by in situ polymerization method.(b) Thesynthesis of new copolyester nanocomposites and the novel carboxylic acid wasintroduced into the PET molecular chains for modifing PET molecular chains andchanging the molecular chain. The interlayer spacing of organic montmorillonite,chemical bonds and thermal stability was studied by X-ray diffraction instrument(XRD), FT-IR and TGA, respectively. The dispersed state of MMT in PET/MMTnanocomposites, the new copolyester and the new copolyesters nanocompositematerial was studied byX-ray diffraction (XRD), scanning electron microscopy(SEM) and transmission electron microscopy (TEM). The properties crystallizationwas studied by polarization microscopy (POM) and differential scanning calorimeter(DSC). Using thermogravimetric analyzer instrument (TGA) test the thermalstability off PET/MMT nanocomposites and the new copolyester nanocomposites.The results show that:(1) In this article, the TDI, MDI wad used to the secondary modified PMMT.The pendant hydroxyl groups of the montmorillonite was modified effectively andthe compatibility with the polymer was enhanced. The dispersed state ofmontmorillonite in PET/MMT nanocomposites and the new copolyesternanocomposites was well.(2) The crystallization temperature ofPET/MMTnanocomposite material was accelerated by the effect of OMMTheterogeneous nucleation. The hydrogen bonds was introducted in the newcopolyester to change the conformation of the molecular chain and to enhance the crystallization stability.(3) The OMMT was hindered volatile thermal decompositionof organic small molecules and improved the thermal stability of PET/MMTnanocomposites and new copolyester nanocomposites. The new copolyester wasstrengthened due to the introduction of hydrogen bonding and enhanced the thermalstability of the polyester.(4) The thermal crystallization of the sample peaks ofPET/MMT nano composite material and pure PET was shifted to the lowtemperatureas the cooling rate increases.The crystallization peak area increased, thesame relative degree of crystallinity was achieved at a lower temperature and neededa longer period of time. Within the same sample at the same time to achieve a higherdegree of crystallinity of the selected cooling rate greater and faster completion ofthe crystallinity at a low rate.(5) The barrier properties of the polyester wasimproved50times through the synthesis of PET/MMT nanocomposites and newcopolyester nanocomposites.