Research On Anti-UV And Anti-yellowing Properties Of Silk Fabrics With Nano-TiO₂ And RE/Nano-TiO₂ Composite

Silk fabric is favored by people for its good wearing properties.However,silk fabric tends to be yellow and breakable under the circumstances of UV,moisture and Oxygen, affecting it's wearing properties and beauty.The purpose of this thesis is to improve the anti-UV and anti-yellowing ability of silk fabric by UV-resistance functional finishing with UV blocking agents nano-TiO₂ and RE/nano-TiO₂ composite.The thesis studied the influence of dispersant's category,dosage and pH value of solution to the dispersion property of nano-TiO₂.The stability of dispersed solution was characterized by using sedimentation volume experiment.The dispersion property of nano-TiO₂ was characterized by Laser Size Analyzer and TEM.The results showed that when pH value of solution was 6～7,PAAS had better dispersion property than other dispersants.The optimum amount of PAAS was 0.075 gram(the amount of nano-TiO₂ was 1.2g).In the thesis,orthogonal experiments and single-factor experiments were adopted to study the anti-UV and anti-yellowing functional finishing of silk fabrics with nano-TiO₂ and RE/nano-TiO₂ composite and preferable finishing process were studied.The results showed that the preferable finishing conditions of finished silk fabrics with nano-TiO₂ were dosage of nano-TiO₂ 25g/L,dipping temperature 30℃and dipping time 40min.In the same dipping temperature and dipping time,the preferable finishing conditions of finished silk fabrics with RE/nano-TiO₂ composite were dosage of nano-TiO₂ 25g/L,dosage of rare earth 4g/L,pH value of solution 5.Finished at the preferable finishing conditions,UPF of silk fabrics respectively reached to 41.97 and 100.64,the decline ratios of whiteness of the finished silk fabrics are 5.49%and 2.8%respective,about one-fourth and half of the original silk fabrics.It was obvious that the anti-UV and anti-yellowing properties of the silk fabrics treated with RE/nano-TiO₂ composite were best,better than the other two finished silk fabrics.The thesis also compared structure and other properties of finished silks with the original silk fabrics.The crystallinity of finished silk fabrics descended.The breaking strength of warp slightly descended,while weft was opposite.The breaking elongation both of warp and weft increased.The handfeel,elastic restoring force, drapablility and permeability of the finished silk fabrics were better than the original silk fabrics.The thesis also tested and compared anti-UV property of the rare earth(RE), nano-TiO₂ powder,RE/nano-TiO₂ composite and their finished silk fabrics in order to study their anti-UV mechanism.The results showed that rare earth powders have a high reflect effect on ultraviolet radiation.Nano-TiO₂ powder and RE/nano-TiO₂ composite powder had the good UV absorption property,and the smaller reflection.The finished silk fabrics with RE had both performance of reflect and absorb UV,but its UV shielding property was worse than the other two finished silk fabrics.The silk fabrics with nano-TiO₂ absorbed UV mainly.The finished silk fabrics with RE/nano-TiO₂ composite had strong absorption of UV radiation,which depended on the nano-TiO₂ for UV absorption and the catalytic role of rare earth,with very low UV transmittance and excellent UV shielding performance.