Preparation Of Nanocellulose Based On Corn Husk And Their Application Research In Nanopaper

With the exhaustion of fossil energy and the more serious problems by the energy and environment pollution,more and more researchers have turned to look for green,efficient and friendly resources.Corn husk as one of the renewable and degradable lignocellulose have been paid more and more attention due to its abundant resources,short periods,great flexibility,outstanding strength and high elongation.Formic acid as an organic acid and could be recovered and resued.Using corn husk by formic acid pretreated to produce valuable materials can be friendly to the environment,and effectively reduce raw materials cost.It is of great significance for realizing the sustainable development of human society.In this study,corn husk was chosen as a research object.Firstly,Corn husk filament(CHF)and corn husk powders(CHP)were separated by mechanical treatment.Then they can be used to prepare valuable materials,such as cellulose nanofibrils,lignin and cellulose nanopaper.The chemical compositions of before and after pretreated corn husk,the effect of CHF and CHP on cellulose products,and the effect of additional lignin on cellulose nanopaper were studied.The results are as the following.(1)The chemical composition and structure characterization of before and after pretreated corn husk via formic acid hydrolysis show that over 90%hemicellulose could be removed;about 80%lignin with high purity could be isolated.The esterification reaction was taken place between formic acid and hydroxyl group of cellulose surface and the crystallinity of cellulose fibers by formic acid hydrolysis was higher than the raw materials.(2)After formic acid hydrolysis,cellulose solid residuals(CSR)was used to fabricate cellulose nanofibrils(CNFs)and then self-assembled cellulose nanopaper was fabricated.The physical properties and characterization results showed that in comparison with CHP,the CHF with longer fibers and higher crystallinity could be easier to hydrolyze,and the resulting CNFs had a smaller diameter and higher crystallinity,leading the final CNP to have better mechanical properties.The maximum tensile strength and toughness of the resultant CNP reached up to 177.0±6.1 MPa and 13.3±1.7 MJ·m-3,respectively.Also,the CNP not only exhibited high crystallinity and great thermal stability,but improved water resistance and good barrier properties.(3)The different weight ratios of the isolated lignin and CNFs were mixed and then blended lignin-containing cellulose nanopaer(LCNP)was frabricated.The results showed that,the S/G(0.14)of Lignin-CHF(L-CHF)was higher compared with that of Lignin-CHP(L-CHP)(0.08).In addition,the wet tensile strength of the obtained LCNP not only remarkably improve to 67 MPa compared with that of CNP(8-22 MPa),but also have great UV-blocking and barrier properties.