纤维素/NMMO溶液及其薄膜的制备与性能研究

Preparation and properties of cellulose/NMMO solution and membrane

以水质量分数为13.3%的N-甲基吗啉-N-氧化物(NMMO)为溶剂溶解棉浆粕,制备质量分数为5%～11%的纤维素/NMMO溶液。将所得溶液制备纤维素薄膜,考察了纤维素/NMMO溶液的稳定性,研究了凝固浴温度和组成对纤维素薄膜的成膜性、断面形态及力学性能的影响。结果表明:纤维素/NMMO溶液随着浓度增大,其粘度先增大后减小,再急剧上升;纤维素/NMMO溶液在玻璃介质中稳定性较好,微量Cu^(2+),Fe^(3+)等杂质存在时,其稳定性显著下降;纤维素薄膜随凝固浴温度升高,其透明性、拉伸强度和断裂伸长率均下降;相对于水,含有乙醇和NMMO的凝固浴能减缓双扩散的速度,使纤维素薄膜的拉伸强度略有提高,断裂伸长率出现不同程度下降。

A cellulose/N-methyl morpholine-N-oxide （NMMO） solution with the mass fraction of 5% -11% was prepared by dissoloving cotton pulp with NMMO containing 13.3% water by mass fraction as a solvent. The obtained solution was used to prepare cellulose membrane. The stability of cellulose/NMMO solution was investigated. The effects of coagulation bath temperature and composition on the formation, fracture morphology and mechanical properties of the cellulose membrane were studied. The results showed that the viscosity of the eellulose/NMMO solution increased, then decreased and finally appeared a steep rise while increasing the solution concentration. The cellulose/NMMO solution exhibited fairly good stability in glass medium. The exitenee of trace Cu^2 ＋ and Fe^3 ＋ caused the stability to decline obviously. The transparency, tensile strength and elongation at break of the cellulose membrane were decreased while elevating the coagulation bath temperature. As compared with water, the coagulation bath containing ethanol and NMMO can depress the double diffusion speed , slightly increase the tensile strength and decrease the elongation at break in different degree.