C-6羧基氧化纤维素醋酸酯的制备和性能

Preparation and Property of Oxidized Cellulose Acetate with C-6 Carboxyl Groups

以溶解级木浆作为原料,通过TEMPO(2,2,6,6四甲基哌啶1氧化物自由基)/NaClO/NaClO_2氧化体系对纤维素C-6羟基进行氧化,经过乙酰化处理后制备出C-6位含羧基的氧化纤维素醋酸酯。用红外光谱(IR)、X-射线衍射(XRD)和核磁共振(NMR)等手段表征了产物的结构,用热重分析(TGA)和差示扫描量热法(DSC)测试了产物的热性能。结果表明:所合成氧化纤维素醋酸酯的C-6位羧基取代度为0.15,乙酰基取代度为2.72(其中C 2为0.93、C-3为0.98、C 6为0.81)且取代均匀性较好;用C-6羟基的选择性氧化预处理可实现纤维素的可控酯化;产物能溶于DMSO(二甲基亚砜);产物的晶型由纤维素Ⅰ型转变成纤维素Ⅱ型。氧化纤维素醋酸酯在185℃发生玻璃化转变,在257℃熔融。乙酰基的接入,使产物的热塑性提高。

Oxidized cellulose acetate with a free carboxylic acid group content of 0.g3mmol/g on C-6 position of the glucose and a total degree of substitution （DS） 2.72, was prepared by oxidizing the dissolving wood pulp with TEMPO/NaCIO/NaCIO2 and then reacted with a mixture of acetic acid and acetic anhydride with sulfuric acid as catalyst. The structure of the product was characterized with Fourier transfer infrared spectroscopy, X-ray diffraction analysis, proton and carbon-13 nuclear magnetic resonance. The thermal properties were tested by thermo-gravimetry analysis and differential scanning calorimetry. The results show the product has a good substitution uniformity with C-2, C-3 and C-6 position＇s acetyl DS of 0.93, 0.98 and 0.81 respectively. The product can dissolve in dimethylsulfoxide, and has good thermoplastic with a melting point of 257 degree celsius. The acetyl access improves thermoplastic of the product.