Modification Of Polyethyleneterephthalate By Different Nucleating Agents And Crystalliztion Property Study

Poly(ethylene terephthalate) is a kind of thermoplastic with good properties. However,the shortage of pure PET crystallization behavior limited its application fields in engineeringplastic. To solve the problem above, nucleating agents should be used. Presently, variousnucleating agents were used in industry improving the crystallization property. With used ofthe nucleating agents, the shortage of degradation of PET molecular chain accompanied.PET and Surlyn8920, Nav101, Sodium benzoate, Nu606nucleating agents blend wereprepared by the twin-screw extruder. Crystallization behavior, morphology and dispersion ofthe nucleating agents were studied by means of differential scanning calorimetry, polarizingmicroscope and scanning electron microscope. The result indicated that all the nucleatingabove improved crystallization behavior, and3%Nu606composition achieved the bestproperties, crystallization temperature shifted from178.5℃to224.9℃. Scanning electronmicroscope and polarizing microscope result showed that Nu606powder well dispersed inPET matrix and all the nucleating agents effectively restrained the spherical crstal in smallersize. In the mechanical and heat-resistant properties test,3%Nu606had the best propertieswith the tensile strength and bending strength inproved from40.6Mpa to76.3Mpa and60.1Mpa to100.7Mpa, Vicat softening temperature increased to195.6℃.Non-isothermal behaviors of different PET composition were studied by Ozawa,Jeziorney and Mo models by DSC. The result indicated that crystallization rate was improvedwhen various nucleating agents were used, and3%Nu606achieved the best properties and thecrystallization rate increased.In order to study the different mechanism of crystallization inducing by different kinds ofnucleating, dimethyl terephthalate, benzoic acid, polyethylene glycol were mixed withnucleating agents to mimic the PET compounds. IR, mass spectra, polarizing microscope,X-ray diffraction were used to study the different compounds. The result showed that Nu606was a kind of physical heterogenous nucleation agent without negative affecting on themolecular weigh of PET.