Dissolution Of Wheat Straw Pulp In LiCl/DMSO And Formationof Lignocellulose Hydrogel

As the abundant renewable resource in nature, lignocellulose has good biocompatibility and biodegradability. The development and application of polymeric materials based on lignocellulose can effectively relieve the energy crisis caused by the shortage of the fossil resources. In this paper, wheat straw soda were pretreated by ethylenediamine(EDA) and then dissolved in 8%LiCl/DMSO solution system. Lignocellulose hydrogel were prepared through solvent exchange and free radical polymerization on the basis of the lignocelluloses/LiCl/DMSO solution.Firstly, oxygen-delignified wheat straw soda pulp were pretreated by EDA and then dissolved in 8%LiCl/DMSO solution system. The effect of the ethylenediamine on the pulp properties and its dissolution-regeneration performance in LiCl/DMSO were studied through XRD and FT-IR. The results showed that the crystal structure of pulps altered but the high crystallinity remained after the EDA pretreatment. And the EDA-pretreated wheat straw pulps were completely dissolved in 8%LiCl/DMSO. Because of the increment of the lignin content, much more time was required to form into the homogeneous solution. The dissolved samples could be regenerated by being poured into water. The yields of the regenerated fractions were ranged from 59.19% to 61.88%. The lignin, polysaccharide, ash, and silicon were all retained well.Secondly, lignocellulose hydrogels were prepared by solvent exchange on the basis of the lignocelluloses/LiCl/DMSO solution. The effect of different lignin content, different dissolution concentration and the different regeneration solution on the properties of hydrogels were characterized by SEM, BET and TGA. The results indicated that the lignocellulose aerogels were three-dimensional porous materials. pore diameter were enlarged with the increase of the lignin content. The denser aerogels could be obtained by high dissolution concentration and the more evenly distributed pore were showed when using ethanol as the regeneration solution.Finally, the temperature sensitive lignocellulose hydrogels were prepared through the semi-IPN with PNIPAAm in the lignocelluloses/LiCl/DMSO solution, using MBAm as the cross-linking agent and AIBN as the initiator. Those gels were characterized by FT-IR, TGA, SEM and DSC. The results showed that the semi-IPN hydrogels were well temperature sensitive with the three-dimensional porous. The swelling ratios decreased with the increasing temperature. The pore diameter were enlarged with the increment of the lignin content, meanwhile, the swelling rate and deswelling rate of the hydrogels were improved.