| Abstract:Wood fibers with high cellulose degree of polymerization (DP) were prepared via microwave-assisted deep eutectic solvents pulping method using spruce wood chips as material and choline chloride/lactic acid as reaction liquid. The effects of molar ratio of choline chloride to lactic acid, reaction temperature, reaction time and water content on the DP were investigated. The consequence showed that DP reached 1998 under conditions of molar ratio of choline chloride to lactic acid of 1:11, reaction temperature of 140℃, reaction time of 45 min, water content of 3 wt%. Microwave heating shortened the time for delignification, which decreased the acid hydrolysis of wood fiber in the acidic medium and maintained high DP of wood fiber. The as-prepared wood fibers with high DP have high zero-distance tensile strength of 261.9 N?m?g-1, and the paper made by these fibers also exhibited an excellent tensile strength of 51.6 MPa and toughness of 2.0 MJ?m-3. |