| Cellulose,the most abundant natural renewable resources on the earth,and it is widely used for the advantages of degradability,environmental friendliness,low cost.The preparation and application of cellulosic composite materials have become a focus of research in the world wide.The output of corn was reach to 260 million tons in 2020 in China,furthermore,near 312 million tons of corn stalks have been produced in the harvest process.Unfortunately,most of these stalks have not been fully utilized.Eucalyptus was introduced in China at 1890,and pineus khasys is also widely planted in Yunnan,Sichuan,and other places.The cultivating area of eucalyptus was 4.6×106 hm2 in 2017.Additionally,most of eucalyptus and pineus khasys were applied in pulping and papermaking industry.All-cellulose composite belongs to a class of high-strength and high-stiffness composite material prepared with regenerated cellulose（as the matrix phase）and undissolved cellulose（as the reinforcing phase）.The preparation method was a immerse method for cellulose partial dissolution.In this paper,corn stalk rind,eucalyptus and Pinus kesiya Pinus kesiyaare collected as the raw resouces of cellulose to prepare all-cellulose composite materials through the partial dissolution method.The results are as follows:（1）Corn stalk rinds were pulped by NaOH-AQ method,eucalyptus pulp and pinus kesiya pulp were purchased from Yunnan Forestry Paper Co.,Ltd.,and the above fiber materials are further delinification by acid sodium chlorite method and deep alkali extraction for hemicellulose removing.These cellulose prepared as paper sheets with a basis weight of 60 g/m2.All-cellulose composite materials were prepared though partial dissolution in ZnCl2 solutions with concentrations of 10%,20%,30%,and 40%,respectively,then regenerated in a deionized water environment.It is found that different concentrations of ZnCl2 solutions show a tendency that to first decrease and then increase with all-cellulose composites in the mechanical properties.The optimal conditions were attained by partial dissolution cellulose concentration is 40%ZnCl2 solution,Young’s modulus is about 478 MPa,the tensile strength is about 13MPa,respectively.（2）The cellulose from three different sources of corn stalk rind,eucalyptus and pinus kesiya were partially dissolved by NaOH/Urea regeneration method at low temperature,and the all-cellulose is dissolved in a deionized water environment.The composite material is washed to neutrality.Studies have found that 4wt%,5wt%,6wt%,7wt%,and 8wt%NaOH/Urea solutions have a certain positive impact on the mechanical properties of the all-cellulose composites.The crystallinity index and crystallinity size of cellulose increase with the concentration of NaOH/Urea solution increases and decreases gradually.The best concentration of partially dissolved cellulose is 6wt%NaOH/Urea solution,which has a Young’s modulus of about 7 GPa and a tensile strength of about 33 MPa.（3）Three different paper sheets of corn stalk rind,eucalyptus and pinus kesiya were prepared by partial dissolution in ZnCl2 solutions with concentrations of 10%,20%,30%and 40%respectively,then regenerated in a deionized water environment,and the obtained materials were characterized.It was found that the mechanical properties of all cellulose adhesive materials were poorer than the original cellulose paper.For the all cellulose adhesive material,with the increase of ZnCl2 solutions dosage,the mechanical properties gradually increase.The optimal condition was attained by partial dissolution cellulose concentration is 10%ZnCl2 solution with corn stalk rind,Young’s modulus is about 476 MPa,the tensile strength is about 4.6 MPa,respectively.The optimal condition was attained by partial dissolution cellulose concentration is 30%ZnCl2 solution with pinus kesiya,Young’s modulus is about 67 MPa,the tensile strength is about 1.2 MPa,respectively.The optimal condition was attained by partial dissolution cellulose concentration is 40%ZnCl2 solution with eucalyptus,Young’s modulus is about 110 MPa,the tensile strength is about 0.4 MPa,respectively. |
