| Titanium dioxide has been widely used in various areas because of its excellentproperties such as non-toxic, antistatic, ultraviolet protection, antibacterial, photocatalytic,self-cleaning, etc. It is well known that PET fiber has a great many of advantages due toits high dimensional stability, high strength, flexibility, thermal and chemical stabilities.The higher moisture absorption and antistatic properties can be endowed with the coatingof titanium dioxide through surface modification. At the same time, the antibacterial,ultraviolet blocking and self-cleaning ability of modified PET fiber are also obtained.In this paper, the optimum processing parameters to synthesize the titanium dioxidenanoparticles using different precursors under hydrothermal conditions are determined bythe single factor analysis method. The chemical structure and properties of PET fibersbefore and after treatments are studied by means of scanning electron microscope,transmission electron microscope, X-ray energy dispersive spectroscope, X-ray diffraction,infrared spectroscopy, thermal gravimetric analysis, differential scanning calorimetry,diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy techniques. Theeffects of alkali etching process, addition of dispersants and doping of metal ionscombined with the precursor on the properties of titanium dioxide nanoparticles areinvestigated under hydrothermal conditions. A layer of titanium dioxide is loaded on thesurfaces of PET fibers using tetrabutyl titanate, titanium sulfate and titanium tetrachloridewith or without disperse dye, respectively. The properties of tensile, friction, dye-uptake,K/S value, fiber diameter, density, heat shrinkage rate, the degree of orientation andcrystallinity for PET fibers are measured. The results can be concluded as follows:(1) PET fibers are treated with hot water in different temperature at high pressure fordifferent time. Compared with the original PET fibers, the tensile properties of modifiedPET fibers decrease with increasing temperature or time. The degree of orientation, fiberdiameter and density follow the same rule. However, the friction factor, heat shrinkagerate and crystallinity increase with the increase of temperature or time. The chemicalstructure of modified PET fibers changes little. PET fibers can be processed usingtetrabutyl titanate as the precursor at120°C for3h or using titanium sulfate at theprecursor at140°C for5h. (2) PET fibers are modified with tetrabutyl titanate, titanium sulfate and titaniumtetrachloride as the precursors under hydrothermal conditions, respectively. Titaniumdioxide nanoparticles with pure anatase are prepared using tetrabutyl titanate or titaniumsulfate. Nano-scaled particles in rutile structure are synthesized using titaniumtetrachloride. The photocatalytic activities of TiO2-coated PET fibers are obtained. Theparticle size of as-prepared titanium dioxide with high photodegradation capability isreduced by adding of polyethylene glycol during the processing. The photocatalyticactivities of titanium dioxide nanoparticles doped with silver or nickel ions can beimproved to some extent. The absorption band is expended to the visible waveband. Thethermal stability and chemical structure change a little. After treatment, the degree oforientation of PET fibers decreases, but the heat shrinkage rate and crystallinity increase.(3) PET fibers are treated with tetrabutyl titanate or titanium sulfate as the precursorin the presence of disperse dye by hydrothermal method. A thin film of titanium dioxide iscoated on fiber surface, and synchronously stained with disperse dye. The color fastnessto sun light is improved due to the existence of titanium dioxide coating. Thephotocatalytic activity can be enhanced by doping with silver ion in preparation oftitanium dioxide. The thermal performance and aggregated state structure of PET fibersare not changed. |
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