Preparation and properties of the hottest chitosan

Research on the preparation and properties of chitosan/cellulose fiber composite paper

release date: Source: China paper making, China paper magazine

1 research background

the rapid development of takeout, e-commerce and other emerging industries has not only brought convenience to human life, but also accelerated the large-scale use of plastic packaging materials. If not controlled, the white pollution caused by waste plastics will seriously endanger the earth on which we live. The global total consumption of plastic is about 400 million tons every year, and only 10% of plastic packaging can be effectively recycled. The rest of waste plastic enters the natural environment, forms micro plastics under the action of natural forces, and then enters the human body through the food chain, directly endangering people's lives and health. It is reported that a person will eat 5g of micro plastic every week, which is equivalent to eating a credit card. With the national development and Reform Commission and other nine departments jointly issuing the notice on Solidly Promoting plastic pollution control, China's plastic ban has entered the implementation stage, and the need to find biodegradable packaging materials to replace plastics is imminent

as a renewable and degradable bio based polymer packaging material, paper is widely used in packaging all kinds of goods, especially in the express industry, which is the largest packaging material. In the context of China's plastic ban, the voice of "replacing plastic with paper" is rising day by day, which will gradually become a new trend and bring development opportunities for further expanding the application of paper in the packaging field. By "replacing plastic with paper", we can effectively alleviate the white pollution caused by petroleum based plastic packaging materials and micro plastics. China's material science and technology industry started late, and promote the sustainable development of human society in the future. Compared with petroleum based plastics, paper still has many shortcomings in performance (such as low strength, poor water resistance, light fastness, low folding resistance, etc.), which hinders its further promotion in the field of packaging. Therefore, by combining paper with bio based polymer materials to prepare paper-based composite packages with excellent performance, the former needs to use rougher abrasive materials to ensure that the polishing process has a larger polishing rate. The solution is to improve all aspects of paper. In 2016, the sales of small household appliances increased by nearly 12% year-on-year, so that it can meet the needs of packaging materials

2 paper introduction

in this paper, chitosan is filled in the pores of paper to form a dense structure through impregnation process, and then chitosan/cellulose fiber composite paper with excellent comprehensive properties is prepared through alkali treatment. The effects of fiber type and impregnation amount on the transparency, haze, tensile strength, elastic modulus, toughness and folding resistance of composite paper are explored, The reason why the composite paper has excellent optical and mechanical properties is analyzed from the perspective of structure. Finally, the effect of alkali treatment on the water resistance of chitosan/cellulose fiber composite paper is studied

2.1 optical properties of chitosan/cellulose fiber composite paper

this paper combines the high transmittance of chitosan with the high scattering properties of wood pulp fiber through the impregnation process, giving the composite paper excellent transmittance and light scattering properties. When the mass ratio of chitosan to cellulose fiber is 3:2, the light transmittance and haze in the visible light region reach more than 88%

2.2 mechanical properties of chitosan/cellulose fiber composite paper

in addition to excellent c-corrugated shrinkage, light transmittance and light scattering properties, the composite paper also shows excellent tensile strength, elastic modulus and folding resistance. The relatively soft chitosan in the composite paper fills the pores between the fibers as a continuous phase, and forms a strong hydrogen bond force with the fibers, so that the excellent mechanical properties of the fibers themselves can be effectively transferred to the composite paper; At the same time, the evenly interlaced fibers are used as the reinforcing phase, which limits the spread of cracks in the composite paper and gives it higher tensile strength and toughness. When the mass ratio of chitosan to cellulose fiber is 3:2, the tensile strength of the composite paper can reach 75 MPa, the toughness is 7.7 mj/m3, and the folding resistance is more than 5000 times

2.3 water resistance of chitosan/cellulose fiber composite paper

in the process of alkali treatment, the cationic primary ammonium radical in chitosan is transformed into neutral primary amino group, which weakens the swelling of chitosan, thus giving the composite paper good water resistance. When the composite paper is completely immersed in water, its saturated water absorption reaches 43.9%, its thickness increases only 12.5%, and the retention of wet tensile strength can reach 38%

3 conclusion

① when the mass ratio of chitosan to cellulose fiber is 3:2, the transmittance and haze in the visible light region reach more than 88%

② when containing 40% Eucalyptus fiber, the composite paper has the best tensile strength (75 MPa), toughness (7.68 mj/m3) and folding resistance (more than 5000 times)

③ after saturated water absorption, the thickness of the composite paper only increases by 12.5%, and can retain 38.1% of the wet tensile strength

chitosan/cellulose fiber composite paper is made from natural biopolymer materials, showing excellent optical, mechanical and good water resistance, which is expected to meet the needs of human society for sustainable bio based packaging materials and help the national green development strategy

article information: Li Guanhui, Mo Qiyong, Hu Wen, Hou Gaoyuan, Xie Hong, Zhang Dejian, Cui Jinyi, Fang Zhiqiang Preparation and properties of chitosan/cellulose fiber composite paper [j] China paper, 2020,39 (11):