再生聚对苯二甲酸乙二醇-1,4-环己烷二甲醇共聚酯的制备及其固相缩聚

Preparation and Solid-State Polycondensation of Regenerated Polyethylene Terephthalate-1,4-Cyclohex‐anedimethanol Copolyester

为了研究废弃聚酯纺织品的高值化再生利用,以废弃聚酯纺织品通过化学法再生制得的高纯度再生对苯二甲酸二甲酯(DMT)单体为主要原料,采用酯交换法通过熔融缩聚合成了再生聚对苯二甲酸乙二醇-1,4-环己烷二甲醇共聚酯(PETG)切片,并对其进行了固相缩聚。采用差示扫描量热(DSC)仪、X射线衍射(XRD)仪、核磁共振氢谱仪和荧光光谱仪等分析仪器对固相缩聚前后的切片性能进行了表征测试。结果表明,再生PETG的熔点约为215℃;再生PETG切片中1,4-环己烷二甲醇(CHDM)的实际共聚比为13.9%。随着固相缩聚反应温度的升高或反应时间的增加,PETG的特性黏度增加,但增速逐渐变得趋缓,且切片的特性黏度与时间的平方根呈线性关系;选择合适的反应条件;固相缩聚后的PETG样品,其DSC升温曲线的熔融峰从低温向高温方向移动,XRD谱图上出现三个衍射峰且愈发尖锐,强度增强,结晶程度增加,端羧基含量降低;当固相缩聚反应温度高于200℃时,切片会发生一定程度的热降解且切片b值升高。

To study the high value recycling of waste polyester textiles,the regenerated polyethylene terephthalate-1,4-cyclo‐hexanedimethanol copolyester(PETG)chips were synthesized by melt polycondensation using transesterification method(DMT)with the high-purity regenerated dimethyl terephthalate(DMT method)monomer obtained from waste polyester textiles through chemical regeneration as the main raw material.Differential scanning calorimetry(DSC),X-ray diffraction(XRD),nuclear magnetic resonance hydrogen spectroscopy(1H-NMR),and fluorescence spectroscopy were used to characterize and test the performance of the slices before and after solid-state polycondensation.The results show that the melting point of regenerated PETG is about 215℃.The actual copolymerization ratio of 1,4-cyclohexanedimethanol(CHDM)in regenerated PETG chips is 13.9%;with the increase of solid state polycondensation temperature or reaction time,the intrinsic viscosity of PETG increases,but the growth rate gradually becomes slower,and the intrinsic viscosity of chips is linear with the square root of time;select appropriate reaction condi‐tions;after solid-phase polycondensation,the melting peak of the DSC heating curve of the PETG sample shifts from low tempera‐ture to high temperature,three diffraction peaks appear on the XRD spectrum,and become increasingly sharp,strength was enhanced,crystallinity and carboxyl end group content were increased;when the solid-phase polycondensation reaction temperature is above 200℃,acertain degree of thermal degradation occurs in the chips and the b value of the chips increases.