低熔点PTT聚酯的合成和非等温结晶性能研究

Isophthalic acid (IPA) and polyethylene glycol (PEG) were used to modify poly(trimethylene terephthalate) to obtain a novel copolyester with low melting point and spinnability, poly(trimethylene terephthalate isophthalate-co-polyethylene glycol) (PTTI-PEG). The effects of different molar ratios of IPA to TPA on the melting temperature (Tm) of poly(trimethylene terephthalate-co-trimethylene isophthalate) (PTTI) were investigated by Differential Scanning Calorimetry (DSC). The experimental results indicated that the crystallinity and the melting temperature obviously decreased with the molar ratio of IPA to TPA increasing. In order to improve the crystallinity, PEG units were imported at the polycondensation stage to obtain PTTI-PEG. DSC showed that PEG can improve the crystallinity. Thermogravimetric Analysis (TGA) illuminated the thermostability of PTTI-PEG was too enough to meet with the need of melt-spinning. The peaks of hydrogen atoms ascribed to the corresponding peaks of IPA and PEG in 1H-NMR. The non-isothermal crystallization behaviors of PTT, PTTI and PTTI-PEG were investigated by DSC, so it was assumed that the non-isothermal crystallization mechanism for PTT and PTTI was the combination of homogenous and heterogeneous nucleation. The activation energy of PTTI-PEG was high, suggesting that the crystallization rate was more sensitive to the temperature. Therefore, it was of great importance to control the temperature in spinning process.