Study Of Polyurethane Modified By Dispersible Titania/Graphene Oxide Composite

Waterborne polyurethane is short for “WPU”. It is one of the most commonly leather finishing agents.It has many excellent unique properties. If the inorganic particles were added to the waterbornepolyurethane, the nanoparticles/polymer matrix nanocomposite will be obtained.The obtainednanocomposite not only can keep the excellent properties of film-forming material itself, but also canendow the finished coating some new properties, such as: waterproof, breathable, self-cleaning,antibacterial mouldproof, flame retardancy and good physical and mechanical properties. In this paper, thedispersible nano-TiO₂, titanium oxide/graphene oxide nanocomposite, functionalized graphene oxide weremixed with industrial water-based polyurethane emulsion through apposite methods.The inorganic nanoparticles/water borne polyurethane （WPU） composite material were successfully obtained by a simple way.（1） Water-soluble anatase TiO₂nanocrystals were prepared with tetrabutyl titanate and ethylene glycolby a simple sol–gel method. Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD）,Thermogravimetry-Differential Thermal Analysis （TG-DTA）, X-ray photoelectron spectroscopy（XPS）, Transmission electron microscope （TEM） and UV–vis were used to study the structure andproperties of water-soluble anatase TiO₂nanocrystals. The TiO₂/EG-WPU complex coatings weresynthesized by adding TiO₂/EG into waterborne polyurethane. The results showed that TiO₂/EGnanocomposites could be well dispersed in waterborne polyurethane. The TiO₂/EG greatly improvedthe solvent resistance, ultraviolet resistance and wear resistance of the waterborne polyurethane, and italso improved the heat resistance of the waterborne polyurethane（2） Graphite oxide（GO） was synthesized from natural graphite powder by a modified Hummersmethod. Graphite oxide was respectively reduced by ethanol amine （MEA）, diethanolamine （DEA）,triethanolamine （TEA） and hydrazine hydrate.The reduced materials were named as MNS, DNS, TNSand GNS.Fourier infrared spectrometer （FT-IR）, X-ray diffraction （XRD）, Thermal analyzer （TGA）,X-ray photoelectron spectroscopy （XPS） and Scanning electron microscope （SEM） were used to studyand compare the structure and properties of MNS, DNS, TNS and GNS. MNS/WPU, DNS/WPU,TNS/WPU and GNS/WPU composite coatings were synthesized by adding these four reducing agentsinto waterborne polyurethane. The results showed that the reduction effect of ethanol amine and diethanolamine was not as well as triethanolamine and hydrazine hydrate. It could be concluded thatthe reducing power were GNS> TNS> MNS> DNS.Reduced materials were added to thepolyurethane material in order to test their frictional resistance,and the results were TNS/WPU>DNS/WPU> MNS/WPU> GNS/WPU.（3） Herein we obtained a titania/graphite oxide （TiO₂/GO） nanocomposite with titaniumtetrachloride（TiCl4） and graphite oxide, using a facile in-situ composite method. The structures andproperties of the nanocomposites were characterized by Fourier transform infrared spectroscopy（FTIR）, X-ray diffraction （XRD）, Thermogravimetry-Differential Thermal Analysis （TG-DTA）, X-rayphotoelectron spectroscopy （XPS）, Transmission electron microscope （TEM） and Scanning electronmicroscope （SEM）. FTIR and XPS tests that the structural layer of graphite during the oxidationprocess bonds to a large number of functional groups and parts of these stable functional groups bondschemically to TiO₂nanoparticles. XRD results show that the peak of the graphite oxide disappearsafter combining with TiO₂nanoparticles. Ultraviolet absorbance spectra show that the UV absorptionpercentage of the waterborne polyurethane presents rising trend with the increasing content of graphiteoxide in polyurethane, and it seems that there exists an optimal additive concentration at which thebest absorbance is achieved. From the experiments, it has been found that TiO₂/GO nanocompositescan be well dispersed in water. TiO₂/GO-WPU complex coatings were prepared by adding TiO₂/GO towaterborne polyurethane （WPU）. The results show that the ultraviolet resistance, the wear resistanceand the thermal stability of the waterborne polyurethane were greatly improved with the addition ofTiO₂/GO nanocomposite.