| Nanomaterials refer to materials that have at least one dimension in the three-dimensional space at the nanometer scale.It is widely used due to its unique size characteristics,including volume effect,surface effect,quantum size,dielectric confinement and quantum tunneling.Plant fiber raw material is a kind of biomass with a wide range of sources,which has many advantages such as green,environmental friendly and recycling.At present,plant fiber nanocellulose has been wildly studied.However,there’s many blanks need to be filled in the field of nanolignin,which is second to cellulose of its products.In this paper,two non-wood fiber materials,switchgrass and wheat straw,were chose as raw material.Switchgrass was the economic crops widely planted in the United States,and wheat strawwas one of the main agricultural and forestry wastes in China.They were treated with recyclable acid,p-TsOH acid,to prepare nanolignin and nano-lignocellulose materials from the filtrate and the filter residue.The nano-lignocellulose membranes are prepared from the material.Specifically includes as the follows:1.By analyzing the reaction processes and results of p-TsOH acid hydrolysis of two non-wood fiber raw materials,exploring the mechanism of action of p-TsOH acid on non-wood fiber raw materials,and constructing p-TsOH hydrolysis delignification and de-xylose mathematical models of are as follows:a.The delignification and de-xylose models of switchgrass are:Residual xylose:XR=(1-0.68-0.254)e-CHF+0.68.e-0 0014-CHF+0.254;Xylose hydrolysis factor:CHF=exp(25.82-70000/8.314T+0.16C)C·t;Lignin remains:LR=(1-0.43-0.468)e-CDF+0.43·e-6·93×10-6.CDF+0.468;Lignin hydrolysis factor:CDF=exp(34.7-95800/8.314T+2.1C)C·t.b.The delignification and de-xylose models of wheat straw are:Residual xylose:XR=(1-0.42-0.1899)e-CHF+0.42·e-0.066·CHF+0.1899;Xylose hydrolysis factor:CHF=exp(21.09-70000/RT+0.1786C)C·t;Lignin remain:LR=(1-0.40-0.35)e-CDF+0.40·e-0 0096·CDF+0.35;Lignin hydrolysis factor:CDF=exp(29.95-95800/RT+0.81C)C·t.The mathematical model can well describe the lignin and xylose content of the samples under different processing conditions,and get more accurate result by design the reaction conditions.2.Study on the nanolignin materials that prepared from two kinds of non-wood fiber materials.The nanolignin material appears as a uniform spheroid or disc in a p-TsOH acid solution with a minimum thickness of less than 10 nm.The acid hydrolysis conditions,dilution rate and centrifugation method all affect the formation of nanolignin.And the effects of acid hydrolysis are an important factor affecting the size,stability and zeta potential of nanolignin particles.3.Nano-lignocellulose material is obtained by mechanical treatment with two non-wood fiber raw material filter residues treated with p-TsOH acid.Through research,the two main factors affecting the size of the nano-lignocellulose material during the preparation process are the treatment conditions of the acid hydrolysis reaction and the degree of fibrillation.The treatment conditions for the acid hydrolysis reaction are the root cause,and the process of the degree of fibrillation is an external factor.The higher concentration of p-TsOH acid solution,the smaller the size,the more concentrated the size distribution,the better the dispersion performance,and the lower the energy consumption required for the later fibrillation.4.The different nano-lignocellulose membranes prepared from the two raw materials of switchgrass and wheat straw were analyzed.The highest tensile index of switchgrass samples was 159.6253 N·m/g of P15T90t120SN4 sample,and the highest tensile index of wheat straw samples is 140.7832 N·m/g of P35T90t120WN8.With the increase in the degree of treatment with p-TsOH acid,the strength of the nanolignin-cellulose membrane prepared from switchgrass decreased,while the wheat straw continued to rise.The calculation model of the specific modulus of nano-lignocellulose membrane was constructed by derivation calculation.The mathematical model can better describe the specific modulus value of the test sample,so as to more fully reflect the elasticity and rigidity of the sample.The mathematical model is described in detail as follows:Sample elongations=1/1。;Actual specific stress:T=F/(g × 1W)×1000;Theoretical specific stress:T’=C1× tanh(C2 ×(s-C3));The square of the theoretical and actual difference:E=(T-T’)2;Specific modulus:M=C1C2×(1-tanh2(C2×(s-C3))).5.Using the constructed specific modulus mathematical model to analyze the nano-lignocellulose membrane,it can be seen that under the reaction conditions involved in this experiment,the membrane sample prepared by wheat straw is quite stable than the modulus,about 5 MN·m/kg,lower than the nano-fibrous film made of bleached eucalyptus pulp with a tensile strain of up to 2.5%.It may be that the nano-lignin particles produced by the acid treatment are advantageous for improving the flexibility,high strain and specific tensile strength of the film.The film samples prepared from the sample of switchgrass can reach up to 7 MN·m/kg,with better strain and tensile strength... |
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