Dissolution Behavior Of Waste Yellow Paper Fibers In Ionic Liquids And Preparation And Properties Of Regenerated Films

Waste yellow papers,composed of lignocellulose and some additives,are a quality low-cost,easily collected and abundant waste paper resources.It is rich in source,inexpensive and easy to recycle.In order to.make rational utilization of these waste resources and obtain high value-added products,ionic liquid 1-allyl-3-methylimidazolium chloride([Amim]Cl)was used as solvent,and dimethyl sulfoxide(DMSO)was added as a co-solvent.The dissolution behavior of waste paper fibers in different dissolution systems was studied.The role of DMSO in the dissolution process was explored.We had rapidly and efficiently prepared regenerated fiber composite films from waste paper by constructing an ionic liquid/inorganic salt system using a dissolution-regeneration-pressure drying method.The main research contents and conclusions are as follows:(1)Alkali treatment can remove impurities such as inks and stickies in the waste paper without intentionally removing lignin and hemicellulose.The pretreated waste paper fiber contained 82.187%cellulose,7.110%hemicellulose,and 7.653%lignin.The cellulose crystal structure was cellulose I.(2)The ball milling process reduced the size of waste paper fibers,destroyed the crystallite of cellulose and increased its solubility in[Amim]Cl.But the dissolution rate of that slowed down.The solubility of waste paper fibers in ionic liquids can be increased by increasing the temperature.[Amim]Cl with 40%DMSO can improve the solvent ability of by reducing the viscosity of[Amim]Cl and increasing its conductivity.Thereby,the dissolution of the waste paper fibers in the ionic liquid can be promoted.(3)The optimum preparation process of the regenerated cellulose base film(P-WYP film)is 90?,4 wt%waste paper fiber addition amount,and reaction time of 4 h.The film had a tensile strength of 68.69 MPa,a high transparency,and a slight roughness on the surface.The treatment of ball milling could improve the transmittance and tensile strength of the regenerated cellulose base film,resulting in a film having a transmittance 70%,tensile strength of 71.16 MPa,and a smooth surface.Adding DMSO can reduce the mechanical strength and clarity of regenerated cellulose based film.The mechanical properties,optical properties and thermal stability of P-WYP films can be effectively improved by adding inorganic salt CaCl2.At the same time,a regenerated cellulose composite film was obtained.The tensile strength of the regenerated cellulose composite film will reach a maximum of 85.86 MPa when the amount of CaCl2 added at 2%.(4)The ionic liquids were recovered by vacuum rotary evaporation method in combination with adsorption.By the method,the impurities generated during the use of the ionic liquid can be removed effectively.The recovery rate reached 85%,and the production cost was reduced.