凝固浴温度对再生纤维素材料结构与性能的影响研究

Effect of Coagulation Bath Temperature on the Structure and Properties of Regenerated Cellulose Materials

以1-烯丙基-3-甲基咪唑氯盐(AmimCl)离子液体为纤维素溶剂,水为凝固浴,通过调控凝固温度分别在不同凝固浴温度下获得再生纤维素气凝胶和再生纤维素膜,研究了再生纤维素气凝胶和再生纤维素膜的微观结构与性能的关系.结果表明:凝固浴温度对再生纤维素气凝胶和再生纤维素膜的微观结构影响显著,进而影响再生纤维素气凝胶膜和再生纤维素膜的光学性能和力学性能,从而建立了凝固浴温度与再生纤维素材料结构和性能之间的关系,对以离子液体为溶剂的再生纤维素材料工业化生产具有一定的指导意义.

Using 1-allyl-3-methylimidazolium chloride(AmimCl)ionic liquid as the cellulose solvent and water as the coagulation bath,regenerated cellulose aerogels and regenerated cellulose films were obtained at different coagulation bath temperatures by regulating the coagulation temperature,and the relationship between the microstructure and properties of regenerated cellulose aerogels and regenerated cellulose membranes was investigated.The results show that the coagulation bath temperature has a significant effect on the microstructure of regenerated cellulose aerogels and regenerated cellulose films,which in turn affects the optical and mechanical properties of regenerated cellulose aerogel films and regenerated cellulose films.When the coagulation bath temperature is low,the diffusion rate of ionic liquid into the coagulation bath is slow,the regeneration rate of cellulose solution is slow,and the structural difference between the surface and the interior of the cellulose hydrogel is smaller and denser.When the coagulation bath temperature is high,the diffusion rate of ionic liquid into the coagulation bath is faster,the regeneration rate of cellulose solution is faster,and the structural difference between the surface and the interior of the cellulose hydrogel is larger and looser.With the increase of the coagulation bath temperature,the pore size of the cellulose aerogel increases,the porosity increases,the specific surface area decreases,and more importantly,the surface pore size is obviously larger than the internal pore size,and this difference increases significantly with the increase of the coagulation bath temperature.The changes in the microstructure of the cellulose aerogel resulted in the decrease of its mechanical strength,Young’s modulus,elongation at break and light transmission from 3.1 MPa,41.5 MPa,24.7% and 88.82% to 0.2 MPa,7.3 MPa,4.6%and 0.07%,respectively.However,with the increase of coagulation bath temperature,the crystallinity of regenerated cellulose film decreases and the surface roughness increases,its mechanical strength,Young’s modulus and elongation at break decreased from 162.3 MPa,5389.8 MPa and 22.6%to 43.1 MPa,3923.4 MPa and 1.4%,respectively,while the light transmission was higher than 80%and the haze increased significantly up to 40%.Thus,the relationship between the coagulation bath temperature and the performance of the regenerated cellulose material was established,which is a guideline for the industrial production of regenerated cellulose material with ionic liquid as the solvent.