液氨预处理对纤维素可及度和反应性的影响

棉短绒纤维素在25℃和1．03MPa压力下分别用液氮预处理120min和180min，纤维素的可及度和反应性大为提高，与未经处理的棉短绒比较．120min和180min液氨处理样的水吸附保持值（VWR）分别提高41％和60％，碘吸附值（VIS）分别提高90％和131％。液氮处理纤维素的羧甲基化反应速率也有较大提高.CMC水溶液的透明度和H-NMR谱的分析表明，取代基沿分子链分布的均一性和失水葡萄糖单元上三个羟基分布的均一性都有明显的提高。

The effect of liquid ammonia pretreatment on the accessibility and carboxymethylation reactivity of cotton linter cellulose

The cotton linter was treated with liquid anhydrous ammonia(L - NH3) under a pres sure of 1. 03MPa at 25℃ for 12Omin and 18Omin. The L - NH3 activation brings adout a consider able increase in accessibilitj and reacti1dty of cellulose. the water retention value of treated samples for 120min and 180min increased 4l% and 60% respectively, and the iodine sorption value increased 90% and 13l% compared with untreated cotton linter. In the carboxymethylation reaction an increase of rcaction iate was found. The observations of the substituent and 1H - NMR spectra of CMC aqueous solutioas ajso showed that the uniformity of the substituent distribution along molecular chain and the re1ative reactivity of the three hydroxyl groups in an anhydroglucose unit were observably improved.