Study On Synthesis And Application Of PTT Copolyester Modified By 1,4-Cyclohexanedimethanol

Poly(1,3-trimethylene terephthalate)(PTT)is a kind of thermoplastic polyester with excellent properties.At present,it is mainly used in the textile field as polyester fiber.Due to the shortcomings of PTT in thermal properties and crystallization properties,its application in the field of engineering plastics is limited.1,4-cyclohexanedimethanol(CHDM)is an important new type of diol.Because of its symmetrical molecular structure and the presence of cyclohexyl,it can effectively improve the thermal stability and chemical resistance of polyester materials.In this thesis,we will use CHDM as modified monomer to synthesize PTT modified copolyester.Poly(1,3-propanediol-co-1,4-cyclohexanedimethanol)(PTTG)was synthesized though 1,3-propanediol(1,3-PDO),terephthalic acid(PTA)and CHDM by changing the amount of PDO and CHDM.The viscosity,~1H NMR,thermal properties and crystallization properties of PTTG copolyester were characterized.At the same time,PTTG copolyester was applied to the blend system to prepare PTT/PTTG binary and ABS/PTT/PTTG ternary blends.The crystallization and mechanical properties of the blends were characterized to explore the effect of PTTG copolyester on the properties of the blends.The intrinsic viscosity of PTTG copolyester was between 0.7-0.9d L/g determine by Ubbelohde viscometer.~1H NMR analysis showed that there was CHDM chain segment in the molecular structure of PTTG copolyester,and with the increase of CHDM content,the content of CHDM chain segment in PTTG copolyester was gradually lower than the actual amount.The results of thermogravimetric analysis showed that the addition of CHDM improved the thermal stability of PTT polyester.The results of differential scanning calorimetry(DSC)showed that the melting point and crystallization temperature of PTTG copolyester decreased,with the increase of CHDM content.When the content of CHDM increased to 15%of the total alcohol,PTTG copolyester had no obvious crystallization peak.The results of non-isothermal crystallization kinetics showed that the crystallization temperature decreased and the crystallization temperature decreased speed up with the increase of cooling rate.The spherulites with obvious cross extinction could be observed by polarizing microscope,which showed that with the increase of CHDM content,the crystallization ability of copolyester gradually decreased.PTTG copolyester with 20%CHDM content was selected to prepare PTT/PTTG binary and ABS/PTT/PTTG ternary blends materials.In the PTT/PTTG binary blend,when the PTTG content was above 50wt%,there was no obvious crystallization peak,which indicated that the crystallization ability of the blend decreased with the increase of PTTG content.The DSC analysis of ABS/PTT/PTTG ternary blends showed that as the proportion of PTTG copolyester increased,the crystallization temperature and crystallization performance can be decreased gradually.The mechanical properties analysis showed that the toughness of PTT Blends could be improved by increasing the use of PTTG.