Abstract

The synthesis and characterization of a novel polyester, based on citric acid and two plasticizers (glycerol -GLY- and ethylene glycol -EG-) using concentration CA:Plasticizer ratios (1:1, 1:2 and 1:3), is described. Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear magnetic resonance (C-NMR) confirmed the functional groups characteristic of polyester, such as O-H, C-H, C-O, and C = O. Scanning Electron Microscopy (SEM) showed the morphology changes when mixed with the plasticizers. Thermogravimetric analysis (TGA) showed that the degradation began at 525 °C for polyester with ethylene glycol, and at 575 °C for polyester with glycerol. The contact angle measurements showed that the polyester obtained is hydrophilic. The use of EG or GLY yielded similar contact angle results (average of 65°). Differential scanning calorimetry (DSC) showed that the crystalline structure of citric acid disappeared due to the polymerization and the effect of plasticizers on the polymer network. The original contribution of this work consists in the use of ethylene glycol as a plasticizer, not reported in the literature, demonstrating the formation of the polyester with better mechanical properties when using ethylene glycol as compared to glycerol.

摘要

描述了一种基于柠檬酸和两种增塑剂（甘油 -GLY- 和乙二醇 -EG-）的新型聚酯的合成和表征，使用浓度 CA:增塑剂比率（1:1、1:2 和 1:3） . 傅里叶变换红外光谱 (FTIR) 和核磁共振 (C-NMR) 证实了聚酯的官能团特征，如 OH、CH、CO 和 C = O。扫描电子显微镜 (SEM) 显示与混合时的形态变化增塑剂。热重分析 (TGA) 表明，聚酯与乙二醇的降解开始于 525 °C，而聚酯与甘油的降解开始于 575 °C。接触角测量表明获得的聚酯是亲水的。EG 或 GLY 的使用产生了类似的接触角结果（平均 65°）。差示扫描量热法 (DSC) 表明，由于聚合和增塑剂对聚合物网络的影响，柠檬酸的晶体结构消失了。这项工作的最初贡献在于使用乙二醇作为增塑剂，文献中没有报道，证明了与甘油相比，使用乙二醇形成的聚酯具有更好的机械性能。