Preparation And Properties Of Waterborne Polyurethane Stabilized By Nanocellulose

Waterborne polyurethane(WPU)is a new type of material that rejects the traditional toxic organic solvent and uses water as the dispersing medium,which is safe and environmentally friendly.Besides,it inherits the excellent performance of traditional solvent based polyurethane and is loved and paid close attention to by the society.With the development of society and the continuous improvement of people's awareness of environmental protection,the development concept of green environmental protection arises at the right moment.Waterborne polyurethane,as a new type of safer and environmentally friendly material,has come into people's sight and become the development direction of polyurethane industry.In order to maintain good emulsion stability,a large number of hydrophilic groups are usually introduced to meet the needs,but this also makes the performance of waterborne polyurethane decline,which still needs to be further improved.In addition,when hydrophilicity is not enough for the stability of waterborne polyurethane,small molecular surfactants are introduced as the emulsifier of waterborne polyurethane to meet the needs of emulsion stability.Small molecular surfactants reduce the properties of the material at the same time,they have certain toxicity,which is contrary to the concept of green and environmental protection of waterborne polyurethane.Therefore,the development of a more green environmental protection,excellent performance of waterborne polyurethane is imminent.In order to improve the existing problems of waterborne polyurethane,on the one hand,choose natural polymer fiber as raw materials,preparation,controlled by different methods for different nano cellulose as emulsifier,waterborne polyurethane,based on the thought of Pickering emulsion with nano cellulose parents,the nano cellulose as the nanoparticles in Pickering emulsion,in the process of emulsified polyurethane adsorption on the surface of polyurethane microspheres,increase the hydrophilic emulsion,realize the stability of the emulsion;On the other hand,nanocellulose has excellent properties such as high stress and biocompatibility,and has abundant hydrophilic groups on the surface,and has good dispersion stability in water,which can be used as nanocellulose filler to strengthen waterborne polyurethane.In this paper,polytetrahydrofuran ether diol(PTHF)and isoflurone diisocyanate(IPDI)were selected as the main reaction monomers,and 2,2-dihydroxymethylpropionic acid(DMBA)was used as the hydro PHILIC chain extender.In polyurethane pre emulsifying process adding nano cellulose as emulsifier,different methods under different content of nano cellulose effect on the properties of waterborne polyurethane,and through the centrifugal emulsion,measuring the tensile properties of the film for its characterization,the results showed that in different ways under different reaction degree,size and surface charge different nano fiber,including the preparation of nano cellulose in hydrochloric acid content was 0.5%,can stable aqueous polyurethane emulsion more than six months,while making the tensile strength of the polyurethane film improved,compared to more traditional emulsifier,water resistance was improved.In addition,the subsequent addition of methyl cellulose and tannic acid gives the waterborne polyurethane a dry and redispersible property.