Micron-nano Dispersion Of Lignocellulose And Preparation Of Composite 3D Printing Wire

Lignocellulose is a renewable biomass resource with abundant reserves in nature.Developing new wood fiber composite 3D printing materials can not only provide an effective way and new method for comprehensive utilization of wood fiber raw materials,but also increase the types and properties of 3D printing materials and open up a broader development space for 3D printing technology.In this thesis,the micro-nano dispersion method and mechanism of lignocellulose treated by glycerol swelling at high temperature,micro-sulfuric acid treatment and simple mechanical treatment were studied.The composite of micro-nano lignocellulose(MNLC)and PLA was prepared,and the 3D printing wire was successfully extruded.(1)Cellulose raw materials were successfully prepared by mechanical dispersion with simple colloidal mill after glycerol swelling and micro-acid treatment combined with mechanical extrusion.The yield of micronanocellulose(MNC)was higher than 85%.High temperature glycerol swelling and micro-acid treatment played an important role in the dispersion of MNC.When the amount of sulphuric acid was 0.64%of the total mass of the system and the acid treatment time was 2 h,the prepared MCN mainly consisted of fibers with diameter less than 100 nm and length about several microns.Even microacid treatment had a great influence on the DP_v of MNC.With the increase of sulfuric acid dosaged,the DP_v of cellulose decreased rapidly from about 650 to nearly 200.The acid treatment time had an effect on the DP_v of cellulose.With the prolongation of acid treatment time,the DP_v of cellulose decreased to less than 200 when the acid treatment time was 3.0 h.The optimum conditions for preparing MCN with high yield and diameter less than 100 nm are as follows:the amount of sulfuric acid is 0.64%of the total mass of the system,and the acid treatment time is 2.0 h.(2)Lignocellulose materials with different lignin content can also be mechanically dispersed by simple colloidal mill to micro-nano lignocellulose(MNLC)with yield close to85%after glycerol swelling and micro-acid treatment combined with mechanical extrusion.High temperature swelling and micro-acid treatment in glycerol medium were the key factors for MNLC dispersion.When the amount of sulfuric acid was 0.64%of the total mass of the system and the treatment time of sulfuric acid was 2 h,lignocellulose with different lignin content can be successfully dispersed into MNLC with diameter less than 100 nm and length of several microns.The existence and content of lignin had little effect on the dispersion of lignocellulose.With the decrease of lignin content,the length of MNLC decreased.Lignin reduced the effect of trace acid on lignocellulose DP_v and the DP_v of lignocellulose containing lignin can be maintained at more than 500.(3)Silane coupling agent(KH550)can effectively improve the interfacial compatibility of the composites,and lignin can play a compatibilizing role to further improve the mechanical properties of the composites.MNC or MNLC and PLA were well blended,and the cross sections showed obvious rough and directional fracture.10%MNC had the best reinforcing effect on PLA.The flexural strength and tensile strength of the composites were 150.1 Mpa and61.7 Mpa,respectively.The existence of lignin improved the interfacial compatibility of the composites.When the content of MNLC was 10%and the content of lignin was 0.37%,the composites had the best mechanical properties.The flexural strength and tensile strength reached 186.7 Mpa and 64.5 Mpa,respectively.MNLC/PLA composite material was extruded into composite 3D printing wire by optimizing conditions.This study will solve the problem of low utilization of lignocellulose,especially lignin and hemicellulose,and realize the printability of lignocellulose and PLA composites containing lignin.The defects of PLA were improved,which provided a new way for the efficient,low cost and green utilization of lignocellulose raw materials.