对苯二甲酸乙二醇2-甲氧基-1,3-丙二醇共聚酯的合成与表征

Synthesis and Characterization of Poly(ethylene-co-2-methoxy-trimethylene terephthalate) Copolyesters

以源自甘油的2-甲氧基-1,3-丙二醇(MPD)代替1,3-丙二醇,采用直接酯化法,合成了一系列不同配比的对苯二甲酸(PTA)乙二醇(EG)2-甲氧基-1,3-丙二醇共聚酯PET-PMT(简称PEMT),并对其进行表征。用红外光谱、核磁共振研究了PEMT的结构和化学组成;用GPC测定了不同配比PEMT的相对分子质量与相对分子质量分布;乌氏粘度计测定了其粘度;用DSC分析了其结晶性能。结果表明,共聚酯PEMT中PMT链段的实际接入量比投料的MPD比例高。且PEMT的粘度明显高于PET的粘度。第三单体MPD的引入,使共聚酯PEMT的结晶性能下降。MPD与PTA的投料摩尔比小于0.4时,共聚酯PEMT的结晶与熔融行为类似于PET。所合成共聚酯PEMT-40(实际n(PMT)∶n(PET)=24∶76)其质均相对分子质量(Mw)为50 216、特性粘度(η)为0.458 dL/g、玻璃化转变温度(Tg)为68.32℃、熔点(Tm)为211.07℃。当MPD与PTA的投料摩尔比大于0.6时,共聚酯为无定形共聚物。

A series of PET-PMT （PEMT） copolyesters were synthesized by direct esterification using terephthalatie acid （ PTA ） -ethylene glycol （EG） -2-methoxy-1,3-propanediol （ MPD, obtained from conversion of bio-glycerol to displace 1,3-propanediol） as co-monomers, with different ratio of PET/PMT. The molecular structure and chemical composition of PEMT were confirmed by FT-IR and ^H NMR. Molecular mass and distributions of PEMT were determined by GPC. The intrinsic viscosity of PEMT was measured, while thermal and crystallization properties of the PEMT were characterized using DSC analysis. Results show that the chain segments of PMT containing in PEMT are much higher than the molar ratio of MPD in feed, and consequently, PEMT has higher intrinsic viscosity than PET. The crystallization degree is decreased with MPD inserting into the polyester. The crystallization and melting behavior of PEMT is similar to that of PET when the feed molar ratio of MPD to PTA is less than 0. 4. The mass-average relative molecular mass （gw ）, intrinsic viscosity （η）, glass transition temperature （ Ts ） , and melting point （ Tm ） of the synthesized PEMT-40 （ the actual ratio of n（PMT）：n（PET） is 24：76） is 50216, 0.458 dL/g, 68.32 ℃, and 211.07 ℃, respectively. However, when the feed molar ratio of MPD to PTA is more than 0. 6, the copolyester of PEMT becomes an amorphous material.