The effect of the most popular plasticizer on the

2022-08-06
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Effects of plasticizers on the surface structure and properties of cellulose films (Part I)

Abstract: natural fibroin films are directly dried without any treatment. The films are brittle and curly, and have little effect. Using glycerol as plasticizer to change the flexibility of chitin film, the flexible shell can be equipped with chitin with different diameters, also known as chitin. The effects of different plasticizing conditions on the surface structure and properties of cellulose film and the plasticizing mechanism of glycerol were studied. Through mechanical property test, surface morphology observation and infrared spectrum analysis, the research shows that glycerol changes the flexibility of cellulose membrane to a certain extent, but at the same time, it makes the mechanical properties of cellulose membrane worse, and the plasticized membrane is easy to lose glycerol and the plasticizing effect is weakened after washing

key words: plasticizer cellulose film infrared spectrum plasticization mechanism

cellulose is a biodegradable polymer, which has excellent neutral energy in use, and can be rapidly decomposed into low molecules under the action of microorganisms after being discarded. Cellulose is a widely existing renewable natural resource in nature. According to expert statistics, hundreds of millions of tons of cellulose can be produced by stripping plants every year when the oil pump is started, which is unmatched by oil. If this precious resource can be effectively and fully utilized, it will bring great benefits to mankind

today, when the ecological environment has been damaged and environmental protection has become a common concern of the international community, the utilization and development of cellulose has become a research topic for scientists at home and abroad, and the production of various membranes from plant cellulose has been included in the development object. Compared with synthetic polymer films, cellulose films have higher dimensional stability, good processability, and are non-toxic, harmless and biodegradable. However, the cellulose film without plasticizing treatment is brittle, curly and easy to tear, which can be said to have little effect. It has been reported that the toughness of the regenerated cellulose membrane from copper ammonia can be improved by blending with casein. Kaimins added triethylphenylammonium hydroxide to cellulose as plasticizer, which can significantly reduce the phase transition temperature of cellulose. The plasticizing effects of glycerol monoethers and diethanolamine derivatives on cellulose membranes have also been reported. They believe that the world-renowned supplier of market research and industry analysis of advanced and intelligent materials, n-tech, released the 2015 (2) 020 color changing material market analysis report. The addition of plasticizers promoted the relaxation process of the amorphous area of cellulose, but these research results were not used in industrial production

the usual method of plasticizing cellulose membrane is to treat it with glycerol aqueous solution, and glycerol plays a role in plasticizing in this process. The concentration of glycerol, plasticizing time and temperature of plasticizing bath all have certain effects on the cellulose membrane, but the change of temperature has little effect on the membrane properties. In order to investigate the effect of glycerol plasticizing treatment on the surface properties and structure of cellulose membrane, glycerol was also used to plasticize and dry the cellulose membrane, and experiments were carried out under different conditions

1 experiment

1.1 sample preparation

prepare 5% (mass fraction, the same later)) cellulose film-forming solution, scrape the film on the glass plate by tape casting method, and use 2mol/L acetic acid as coagulation bath to prepare cellulose film. Plasticize the film with water, 5%, 15%, 25%, 30%, 50% glycerol/water solution at 35 ℃ for 30rain. The plasticized cellulose films are recorded as NN (n=0, 1, 2, 3, 4, 5, 6). Under the condition that the concentration of 30% glycerin aqueous solution and the temperature of plasticizing bath are constant at 35 ℃. When the plasticizing time t is changed, the plasticized cellulose film is recorded as TT (t=0, 5, 10, 30, 60, 18O). The prepared cellulose film is naturally dried and ready for use

2 test and analysis

2.1 effect of glycerol concentration

the membrane was immersed in different concentrations of glycerol aqueous solutions, and then dried at room temperature. From the magnified photos under the microscope in Figure 1, it can be seen that the cellulose membrane, plasticized by 5% and 10% glycerol aqueous solutions, has a curly surface, tight edge shrinkage and brittle film; Plasticized by 20% glycerin solution, the film is smooth and glossy, although there are slight wrinkles on the surface; After treated with 30% glycerin aqueous solution, the film surface was smooth, smooth, glossy and felt better. However, when the concentration of plasticizing bath is higher than 50%, the natural drying time of the membrane is longer and it is difficult to dry

Table 1 lists the effect of glycerol aqueous solution concentration on the mechanical properties of the membrane. It can be seen that the tensile strength of the film decreases and the elongation at break increases after plasticization. The film strength decreased with the increase of glycerol concentration. When glycerol was increased from 0% to 10%, the film strength decreased most obviously

2.2 effect of plasticizing time

the membrane is diffused in glycerin solution, and there is a process of water and glycerin exchange. In the actual process, some people have been immersed for 24 hours to obtain good results. In order to improve the work efficiency and shorten the work time, 30% glycerin solution is used to conduct the immersion experiment at 35 ℃ to determine the water flux and cutoff rate of the treated membrane. The data results are listed in Table 2, After soaking for a period of time, the interception performance is improved in varying degrees, but the change of water flux is not very obvious

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