Study On Watweborne, Microstructure And Self-Assembly Behavior Of Natural Polymer Based On Cellulose

Solvent-based nitrocellulose coatings and solvent-based cellulose acetateadhesives are widely used because of their fast drying as well as excellentperformance of decoration and construction. However, with the increasingdemands of environmental protection, many countries and regions havepromulgated many laws and standards which strictly restrict the volatile organiccompounds (VOC) content of coatings and adhesives. It is a great challenge fortraditional nitrocellulose coatings and cellulose acetate adhesives with a largenumber of organic solvents to meet the requirements of these laws and standards.So how to reduce VOC content has become the bottleneck which greatly restrictsthe application and development of nitrocellulose coatings and cellulose acetateadhesives.The most effective way to solve this problem is to translatesolvent-based coatings and adhesives to waterborne coatings and adhesives withaqueous resin as base material and water as dispersing medium, whose VOCcontent is easily reduced to be zero. Therefore, study on preparation andproperties of waterborne nitrocellulose resin and cellulose acetate resin hasimportant application value and wide market prospect.In this research, a novel self-emulsifying method was designed first.Synthetic formula and technology conditions were determined and optimized byorthogonal experiment, on the basis of which waterborne cellulose esterderivatives emulsions with good peformance were successfully prepared.Emulsion coatings were modified by means of crosslinking modification agents.Microstructure and self-assembly behavior in the film-forming process ofwaterborne cellulose ester derivatives were preliminarily studied. The mainresearch contents and conclusions of this thesis are stated as follows:1.The method of self-emulsification, in which the hydrophilic groups fromcarbamate were introduced into the macromolecular chain of cellulose esterderivatives through its hydroxyl’s reaction activity, was designed by thedetermination of diisocyanate and bis (hydroxymethyl) propionic acid as raw materials. The method is based that hydrophilic group was introduced tomacromolecular chain of cellulose ester derivatives, the emulsion with smallerdiameter particles was self-emulsifying dispersion in the water.2.The effects of various technical parameters on the synthesis yield ofwaterborne cellulose ester derivatives emulsions were investigated and theoptimal processing conditions were found through orthogonal experiment. Thestructure and performance of production were analyzed. It was showed by the IRtest that ammonia ester bonds and hydrophilic groups are both introduced tonitrocellulose and cellulose acetate successfully on the precondition ofmaintaining its main structure and according with the molecule design. Thestability of emulsion is excellent. The mean size of nitrocellulose emulsionparticles is162nm, Zeta potential value of emulsion is-54.49mV. And the meansize of cellulose acetate emulsion particles is113.5nm, Zeta potential value ofemulsion is-49.98mV.3.Coatings of waterborne nitrocellulose emulsion were modified by theaziridine crosslinking agent(ACL) and silane coupling agent(SCL). Films ofwaterborne cellulose acetate emulsion were modified by epoxy resin(EP) andepichlorohydrin(ECH). Effects of different modifier content on stability ofemulsion and water-resistant, thermal stability, mechanical property and otherproperties were studied. So，the best percentage of modifier content was found.4.Effects of influence factors on stability and film-forming property ofwaterborne cellulose ester derivatives emulsion were discussed with themicrostructure and self-assembly behavior in the film-forming process ofwaterborne cellulose ester derivatives as the breakthrough point, stabilitymechanism of emulsion and main factors on film performance were put forward.Effects of emulsion particle size and Zeta potential on stability of emulsion andparticle size and its distribution on the final properties of film were discussed.