The Synthesis Of Copolyesters Modified By Polyalcohols,preparation Of Fibers And Study Of The Structure And Property

Polyethylene terephthalate (PET) is synthesized by terephthalic acid (PTA) andethylene glycol (EG) through esterification and polycondensation reaction. It has a lotof advantages,for example low cost, high breaking strength, good light fastness andheat resistance property, moderate resilience, excellent heat-setting and goodantimicrobial erosion property, which make it be widely used in textile and clothingsector. But it also has some shortcomings such as poor hydrophilic, easy to producestatic property, diffcult to dye and hard feeling, which limit its application in someways. As the result, the idea that polyester would be modified by specific technologyto overcome its disadvantages and the modified fibers would alsopossess itsadvantage at the same time come to people,s mind.The thesis synthesizes different kinds of multi-component polyesters bychoosing the proper reaction conditions with the third monomer SIPE and the fourthmonomer NPG on the base of PTA and EG. The structure and properties of thesynthesized samples were characterized by1H-NMR spectroscopy, fourier transforminfrared spectroscopy (FT-IR), ubbelohde viscometer test, differential scanningcalorimetry (DSC), thermogravimetry analysis (TG),1D Wide angle X-ray diffraction(WAXD). Meanwhile, the synthesized copolyester samples were spun. The bestdrawing process copolyester fibers were explored and the corresponding fiber,properties of mechanical property, hydrophilic property, crystallization, orientation,boiling water shrinkage percentage were characterized. The results were as follows:1．1H-NMR spectroscopy studies showed that when the third monomer SIPEfeeding ratio is at2.5mol%and the fourth monomer NPG feeding ratio is at0-9mol%,the proportion of the third monomer SIPE and the fourth monomer NPG in polymer are almost the same with the feeding ratio proportion of SIPE and NPG.2．The FT-IR results showed that there were several major feature peaks showedon the spectrogram, for example the peaks at727cm-1and1372cm-1.3．The results of ubbelohde viscometer test showed that with the increase ofSIPE content, the intrinsic viscosity of the copolyester gradually decrease.4．The DSC results showed that the glass transition temperature (Tg) and themelting point(Tm) reduced with the increase of NPG content, but the coldcrystallization temperature (Tcc) increase. As the similar trend to crystallization abilityand crystallinity. The DSC results also showed that when the fourth monomer NPGfeeding ratio is around9mol%, the copolyester has no crystallization peak and themelting peak.5．TG results showed that the introduction of the fourth monomer NPG does notweaken the thermal stability of copolyester.6．WAXD results showed that with the increase of NPG content, the diffractionpeak position and the crystal structure of copolyesters are not changed butcrystallinity decrease.7．With the the increase of NPG content, the tensile strength and modulus of thefibers decrease, while the breaking-elongation increased. It showed that NPGdeteriorated the mechanical properties of the fibers, but the fibers softness becamebetter. As the drawing ratio increasing, the breaking strength and modulus ofcopolyester fibers increase. The better drawing ratio is4.3times.8．The test results showed that with the the increase of NPG content, the contactangle and moisture regain of fibers increase and the hygroscopic and hydrophilicproperties of fibers improve, as the similar trend to boiling water shrinkagepercentage.9．The crystallinity and orientation of the fibers desease when NPG contentincreases.