Preparation And Performance Research Of The High Barrier New Polyester Bottle Grade Chips

In this paper,the polyester(PET) macromolecular chains have been introduced dicarboxylic acid containing amide bond and isosorbide by copolymerization method to change the structure of the polyester molecular chain.Thus affecting the structure of the molecule chains of condensed matter, and have a significant impact barrier properties of polyester.Firstly, a dicarboxylic acid containing an amide bond was synthesized by4,4’-diamino-diphenyl methane(MDA) and succinic anhydride, known as the third monomer.And 0.3%, 0.5%, 1.0% and 3.0%(based on the molar amount of terephthalic acid,PTA) of the third monomers had respectively co-condensation with terephthalic acid(PTA)and ethylene glycol(EG) to obtain a series of new polyesters containing amide bond,named PEAT-1, PEAT-2, PEAT-3, PEAT-4.The performances of third monomer and new polyesters were tested by nuclear magnetic resonance(1H-NMR), infrared spectroscopy(FT-IR), thermal gravimetric analysis(TG), differential scanning calorimetry(DSC), the melt flow rate test analysis(MI), differential pressure method barrier test etc.The results show that the synthesis of third monomer was successful synthesized. With the increase of the added amount of the third monomer, the melt index(MI) of new polyesters were constantly decreasing and the flowing properties are deteriorated. The thermal degradation temperatures have little change.When the third monomer was added in an amount of 0.5%, compared to pure PET, the glass transition temperature(Tg) of novel polyester has increased approximately 5℃, little change in melting point(Tm). And the oxygen permeability rate has reduced to 0.7248ml/pkg.d from2.1372ml/pkg.d of pure PET, showed that the introduction of the third monomer has effectively improved gas barrier properties of the polyester.Secondly, due to the addition of the third monomer, amide bonds were introduced in the molecular chain of the polyester to produce hydrogen bonds between the molecular chains,having its melt viscosity increased and fluidity deteriorated. The Tg of novel polyester PEAT is not high, conducive to the bottle after high-temperature sterilization. So the fourth monomer-isosorbide was introduced as a rigid segment to copolymerization of another new polyester PEISAT. The performances of new polyester PEISAT were tested by thermalgravimetric analysis(TG), differential scanning calorimetry(DSC), the melt flow rate test analysis(MI), differential pressure method testing etc.The results showed that with the increase of the added amount of isosorbide, the initial decomposition temperature of new polyester PESIAT was slightly improved and its final weight loss had increased. The glass transition temperature Tg of PEISAT had significantly increased to 90 ℃, while its melting temperature Tm had declined.The melt index of PEISAT increased significantly and its flow property improved. Its oxygen permeability first decreased and then increased, and the minimum is 0.5831ml/pkg.d, explained isosorbide joined not only improved the barrier properties of polyester, but also improved the operating temperature of the polyester..Finally, PEAT and PEISAT were respectively analyzed to study the non-isothermal crystallization kinetics and isothermal crystallization in this paper. The condensed state structure of new polyesters were analyzed by X-ray diffraction(XRD) and polarized optical microscopy(POM).The results show that the third monomer and isosorbide were added to make the crystallization rate of new copolyester decrease, grain refinement become small, the crystallization behavior decreased.