Synthesis And Modification Of Hydroxyl Terminated Hyperbranched Polyester And Its Effect On PET Crystallization

PET thermoplastic resin possess high melting point,chemical resistance,good electrical insulation and wear-resisting.But the slow crystallization rate of PET lead to its molding process takes a long time,resulting in the process of bending,deformation and other defects[1].Therefore,it is of practical significance to improve the crystallization rate of PET.In this paper,three generations of AB2 type hydroxyl radical hyperbranched polyester(HBP-OH)[2]were synthesized by using trimethylolpropane and 2,2-dimethylol propionic acid as raw materials.Then,the hyperbranched polyester(HBP-OTS)was modified by the oxidation of the hydroxyl group of the three generation hyperbranched polyester with sulfonyl chloride.By C13NMR,FTIR and GPC characterization,the results showed that HBP-OTS and HBP-OH was successfully synthesized.And the sulfonylation rate of each HBP-OTS was calculated.Then tested by TGA,The results show that the thermal decomposition temperature of HBP-OTS is about 260?,which can meet the PET melt shear temperature of 250?The shear blending of G2,G3,G4 HBP-OTS/PET blends with mass fraction(HBP-OTS)of 1%,3%,and 5%,was carried out by a shear rheometer for 5 min.For each mold will blend spline and drawing into strips made respectively by using a pendulum impact instrument and universal testing machine for impact and tensile tests.HBP-OTS slightly decreases the crystallinity and melting point of PET.With the increase of HBP-OTS content,the tensile strength(TS)and impact strength(IS)of PET increased first and then decreased,and the TS and IS of PET/0.03 G3 HBP-OTS blends were the highest.Were 63.9MPa,9.77KJ/m2.Compared with pure PET,6.3%and 4.5%respectively.Through the method of Jezoirny[3]DSC and non isothermal crystallization kinetics of the blends showed that The half crystallization time(t1/2)of all blends decreased,and the crystallization rate constant(Z)increased.Half crystallization time of 3%G3HBP-OTS/PET blends is minimum,the crystallization rate constant(Z),is about 15 times higher than that of pure PET Z value.It shows that the crystallization rate is the fastest.The Avrami index of PET was decreased with the addition of HBP-OTS,indicating that HBP-OTS acted as a heterogeneous nucleation agent.