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基于1,8-二氮杂二环十一碳-7-烯(DBU)存在下,纤维素与CO_2在二甲基亚砜(DMSO)中反应生成纤维素可逆聚离子液体反应的原理,实现纤维素溶解与活化,同时实现原位DBU催化棉浆纤维素与苯甲酸甲酯的转酯化反应,成功制备了不同取代度的纤维素苯甲酸酯.探索了不同反应时间、反应温度、苯甲酸甲酯与纤维素脱水葡萄糖单元(AGU)比例对纤维素取代度的影响,并对纤维素苯甲酸酯进行核磁共振氢谱、碳谱、红外光谱、差示扫描量热法(DSC)、热重分析(TGA)及X射线衍射(XRD)表征.结果表明,转酯化反应温度为115℃,苯甲酸甲酯与AGU比例为5:1,反应24 h时取代度最高能达到0.53.和纤维素相比,纤维素苯甲酸酯有明显的玻璃化转变温度,但其热稳定性下降.
Based on the principle of reaction of cellulose with CO_2 in dimethylsulfoxide (DMSO) to produce cellulose reversible polyionic liquid in the presence of 1,8-diazabicycloundec-7-ene (DBU) Cellulose dissolution and activation, and at the same time in situ DBU catalyzed transesterification of cotton pulp cellulose and methyl benzoate, successfully prepared cellulose benzoate with different degrees of substitution.Exploration of different reaction time, reaction temperature, The effect of the ratio of methyl benzoate to cellulose anhydroglucose units (AGU) on the degree of cellulose substitution was investigated. The molecular weights of cellulose benzoate were determined by 1H NMR, GC, IR and DSC (TGA) and X-ray diffraction (XRD). The results showed that the transesterification temperature was 115 ℃ and the ratio of methyl benzoate to AGU was 5: 1. The highest degree of substitution 0.53. Cellulose benzoate has a significant glass transition temperature compared to cellulose, but its thermal stability is reduced.