Research Of Waterborne Polyurethane Modified By Butyl Acrylate/Acrylonitrile And Nanosilica

In this paper, polyether type of waterborne polyurethane emulsions were prepared bythe method of prepolymerization, modified by butyl acrylate/acrylonitrile and nanosilicarespectively. The main research results were summarized as follows:1. Study on synthesis and properties of polyether type of waterborne polyurethaneemulsions based on toluene diisocyanate(WPU)WPU were synthesized from toluene diisocyanate(TDI), polyether glycol(N220),dimethylolpropanoic acid (DMPA),1,4-butanediol(BDO) as the main raw materials.Theeffects of amount of DMPA, total mole rate of–NCO/-OH on the properties of emulsion,water resistance and mechanical properties of membrane were investigated by FTIR,particle size analyzer, and Differential Scanning Calorimetry(DSC) and so on. Theexperimental results showed that with the increasing of DMPA content, stability, viscosityof emulsion increased, but the average particle size decreased, the dispersivity of particlesize become narrower, the tensile strength of film increased, but the elongation at break andthe resistance to water decreased. With increasing the value of R, stability, viscosity ofemulsion decreased, but the average particle size increased, the dispersivity of particle sizebecome wider, the tensile strength of film and the resistance to water increased, but theelongation at break decreased. The best WPU can be obtained by the following preparationsteps: The PU-1in which the total mole rate of–NCO/-OH was1.2and the content ofDMPA was6.0wt%, was neutralized by triethylamine(TEA). The obtainedanionomer was allowed to disperse into demonized water with vigorous stirring andthe polymer chain was extended by reacting with ethylene diamine(EA).2. Study on synthesis and properties of poly(butyl acrylate-acrylonitrile)/waterbornepolyurethane hybrid emulsionsDouble bond-end capped polyurethane emulsions were prepared with PU-1and2-hydroxyethyl acrylate(HEA). Using synthesize double bond-end capped polyurethaneemulsions as the seed emulsions, adding butyl acrylate and acrylonitrile(by the weight ratio:1:1), poly(butyl acrylate-acrylonitrile)/waterborne polyurethane hybrid emulsions weresynthesized by free radical copolymerization. The effects of content of monomers on theproperties of hybrid emulsions and membrane were characterized by FTIR,TGA andTEM.The results showed with the increasing of monomers content, the stability of hybrid emulsions decreased, but the average particle size increased, the resistance to water andheat-resistance of film were improved, the tensile strength increased at first and thendecreased, but the elongation at break decreased. When the content of monomers was40wt%, the overall performance of hybrid emulsions were execellent.3. Study on preparation and surface modification of nanosilicaNanosilica spherical particles were prepared by the St ber method. Then nanosilicawas modified by coupling agent grafting method and TDI activation method respectively.The results of Fourier transform infrared spectroscopy(FTIR), thermal gravimetricanalysis(TGA) and transmission electron microscopy(TEM) showed that the nanosilicaparticles were spherical structure and combined with the grafted organic via chemicalbonds and a larger grafting ratio was obtained via TDI activation method.4. Study on preparation and properties of nanosilica/waterborne polyurethanecompositesUsing the formula of preparation PU-1, nanosilica/waterborne polyurethanecomposites were synthesized by means of mechanical blending and in situ polymerization.The influence of content of nanosilica on performance of nanosilica/waterbornepolyurethane composites were characterized by FTIR, viscosity testers and TGAand so on.The result showed that with the increasing of nanosilica content, thestability of hybrid emulsions increased gradually, heat-resistance of film were improvedgradually, the tensile strength and the elongation at break increased at first and thendecreased, water absorption decreased at first and then increased.When the content ofnanosilica was5wt%, the water absorption of film was7.3%at the lowest value.