The methanolysis of poly(ethylene terephthalate) (PET) copolymers containing 5-nitroisophthalic units was investigated. Random copolyesters containing 10 and 30 mol % of such units were prepared via a two-step melt copolycondensation of bis(2-hydroxyethyl) terephthalate (BHET) and bis(2-hydroxyethyl) 5-nitroisophthalate (BHENI) in the presence of tetrabutyl titanate as a catalyst. First, the susceptibility of these two comonomers toward methanolysis was evaluated, and their reaction rates were estimated with high-performance liquid chromatography. BHENI appeared to be much more reactive than both BHET and bis(2-hydroxyethyl) isophthalate. The methanolysis of PET and the copolyesters was carried out at 100 °C, and the degradation process was followed by changes in the weight and viscosity, gel permeation chromatography, differential scanning calorimetry, and ¹H and ¹³C NMR spectroscopy. The copolyesters degraded faster than PET, and the rate of degradation increased with the content of nitrated units. The products resulting from methanolysis were concluded to be dimethyl terephthalate, dimethyl 5-nitroisophthalate, ethylene glycol, and small, soluble oligomers. For both PET and the copolyesters, an increase in crystallinity was observed during the degradation process, indicating that methanolysis preferentially occurred in the amorphous phase. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 76–87, 2002

中文翻译：

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含有5-硝基间苯二甲酸单元的聚对苯二甲酸乙二醇酯共聚物。三，甲醇降解

研究了含有5-硝基间苯二甲酸单元的聚对苯二甲酸乙二醇酯（PET）共聚物的甲醇分解。在钛酸四丁酯的存在下，通过对苯二甲酸双（2-羟乙基）对苯二甲酸酯（BHET）和双（2-羟乙基）5-硝基间苯二甲酸双酯（BHENI）的两步熔融共缩聚反应，制备包含10和30 mol％此类单元的无规共聚酯。作为催化剂。首先，评估了这两种共聚单体对甲醇分解的敏感性，并通过高效液相色谱法评估了它们的反应速率。BHENI似乎比BHET和间苯二甲酸双（2-羟乙基）酯都更具反应性。PET和共聚酯的甲醇分解反应在100°C下进行，降解过程包括重量和粘度的变化，凝胶渗透色谱法，¹ H和¹³ C NMR光谱。共聚酯的降解速度比PET快，并且降解速率随硝化单元的含量增加而增加。由甲醇裂解得到的产物被推断为对苯二甲酸二甲酯，5-硝基间苯二甲酸二甲酯，乙二醇和小的可溶低聚物。对于PET和共聚酯，在降解过程中均观察到结晶度的增加，表明甲醇分解优先发生在无定形相中。©2001 John Wiley＆Sons，Inc. J Polym Sci A部分：Polym Chem 40：76-87，2002