Study On Cellulose Sponge Using Ionic Liquid As Solvent

The sponge is one of the most common items and the essential consumables in our daily life, which can be widely used in the fields of the suit liner, cleaning, filtration, padding, shock absorption and sound insulation etc. Currently, the main chemical components of traditional sponges are organic synthetic polymers, such as polyurethane, polyester, poly(vinyl alcohol)(PVA) etc. The production technologies of traditional sponges are quite mature, but there are still some obvious drawbacks, such as high resource and energy consumption, difficult degradation of abandoned sponges, not easy to recycling, serious environmental pollution and so on. As one of green resources, biodegradable natural cellulose has aroused people’s widespread concern. Instead of organic synthetic polymer, cellulose can be used as the main ingredients to prepare cellulose sponge, which can have many advantages:renewable raw material resource, higher hydrophilicity, favourable water absorption rate and sewage suction abilities, easy to dry, no environmental pollution, and so on. Therefore, the preparation of cellulose sponge is good in practical applications and ecological benefit. Recently, it was just at the beginning of the research on sponges prepared by cellulose at home and abroad. Besides some patents, the research on cellulose sponges using ionic liquid as solvent is rarely reported.Therefore, in this thesis, cellulose sponges were prepared by using ionic liquid1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as the solvent, cotton pulp as raw material, absorbent cotton as the reinforcing cellulose, and using physical pore forming method or physical pore forming&chemical foaming method, respectively. The effects of different factors on the morphological structure and properties of cellulose sponge were investigated. On this basis, the difference of structure and properties between our own cellulose sponge samples and several commercial sponges were compared, and the development prospects and market applications of cellulose sponge using ionic liquids as solvent were also proposed.In this thesis, cellulose sponges were firstly prepared by using physical pore-forming agent as pore-forming system and the morphological structure and properties of cellulose sponges were characterized by means of SEM, WXRD, centrifuge, universal material testing machine, sclerometer etc. The results showed that among three kinds of cellulose sponges prepared by using sodium chloride, anhydrous sodium carbonate and anhydrous sodium sulfate as the pore forming agents respectively, the cellulose sponge prepared by using anhydrous sodium sulfate as pore forming agent showed the better water adsorption, moisture retention capacity and mechanical properties, as well as more homogeneous and regular pore structure. With the increase of the content of the pore forming agent, the porosity of cellulose sponge was further improved, and the water adsorption and moisture retention capacity, and softness of cellulose sponge also increased, whereas the tensile strength of cellulose sponge decreased. Moreover, more reinforcing cellulose had a less effect on the pore structure of cellulose sponge, but the water adsorption and moisture retention capacity, and tensile strength of cellulose sponge could be improved in some degree. With the increase of the total content of cellulose, the tensile strength of cellulose sponge increased, whereas the water adsorption and moisture retention capacity and softness decreased.In order to get larger pore in the cellulose sponge, the chemical foaming agent was added into the pore-forming system besides physical pore-forming agent, by which foamed cellulose sponge was prepared. The morphological structure and properties of cellulose sponge, prepared by using p-toluenesulfonhydrazide or diethyl azodicarboxylate as chemical foaming agent, were compared with cellulose sponge prepared without chemical foaming agent. The results showed that after the addition of chemical foaming agent, the cellulose sponge could form the larger pore structure, and its porosity, the water adsorption and moisture retention capacity, and softness were improved. Compared with diethyl azodicarboxylate, p-toluenesulfonhydrazide was lower-cost, relatively stable and controllable during foaming process, and the prepared cellulose sponge showed more and larger pore structure, as well as better water absorbability, moisture retention capacity and softness. Under the conditions of this thesis, the sponge with better overall performance could be prepared when the content of pore-forming agent and chemical foaming agent were3times and4%of the mass of cellulose/[Bmim]Cl solution respectively. Compared with the cellulose sponge without chemical foaming agent, the porosity of cellulose sponge could reach to about97.8%, and the water adsorption and moisture retention capacity were increased about80%and50%, respectively, and softness of cellulose sponge was also improved in some degree.Based on the above work, the morphological structure and properties of our own cellulose sponges, prepared by using physical pore forming method or physical pore forming&chemical foaming method respectively, were compared with several commercial sponges including PVA cleansing sponges and polyurethane, PET cleaning sponges. The results showed that the morphological structure, the water adsorption and moisture retention capacity, the tensile strength and the thermal properties of the two own cellulose sponges could reach the relevant requirements of market. In addition, the porosity and moisture retention capacity of the two own cellulose sponges were significantly better than the four market sponge products. Therefore, it can be seen that cellulose sponge using ionic liquid as the solvent has a good market application prospect.