Functionalization Of Silk Fabric Treated With The Extracts From Dioscorea Cirrhosa Tuber

Gambiered Guangdong silk with unique performance is of great value in history and culture,and its manufacture is a typical example of the application of tannins to the chemical processing of textiles.At present,there have been little reports on the research on the structures and properties(particularly functions)of Gambiered Guangdong silk by modern analytical techniques,and the application of plant tannins for textile processing purposes.In the light of the water-soluble,non-toxic,cheap and available,and abundant characteristics of plant tannins as well as the eco-friendliness and high exploitation value for the application of plant tannins to the wet processing of textiles,in this work,the color characteristics,structures,chemical compositions,and functionalities of Gambiered Guangdong silk were firstly studied by means of instrumental characterization and analysis.The good flame retardancy of Gambiered Guangdong silk was found for the first time.Based on this new discovery,the condensed tannin extract from Dioscorea cirrhosa(DC)tubers was successfully applied for the first time to the flame retardant treatment of silk textiles by an impregnation technique,in the absence of metallic salts and other flame retardants;in this section,the investigations were focused on the application conditions of DC extracts,and the flame retardancy and flame retardant mechanism of treated silk fabrics;additionally,the antibacterial and antioxidant functions of treated silk fabrics were evaluated.Subsequently,six metallic salts were used in the post-mordanting of the silk fabrics treated with DC extracts;the objectives of this research were to achieve the simultaneous dyeing and functionalization of silk textiles,and to address the issues present in silk fabrics treated with DC extracts,e.g.,monotonous color,poor rub fastness and terrible light fastness.Finally,the silk fabrics treated with DC extracts were subjected to the treatment of polyethyleneimine for the purpose of the further improvement in flame resistance.The important conclusions were drawn as follows:(1)The coating of condensed tannins from Dioscorea cirrhosa tuber and the subsequent iron salt mordanting had no impact on the crystalline structure of silk fiber,but significantly changed the morphological structure,chemical compositions and thermal stability of silk fabric.The exposure of the tannin-coated fabric to sunlight made silk fabric become darker due to the oxidation of tannins.Iron mainly distributed on the face side of silk fabric,and its complexation with condensed tannins gave the face side a glossy black appearance.Interestingly,the good flame retardant,waterproof and antistatic properties of the fabric were unexpectedly found.Tannin coating acted as a char forming agent during combustion,and accordingly it imparted good flame retardancy to silk fabric.The blocking of the grooves between the fibers by coated tannin and tannin-iron complexes made silk fabric waterproof.In addition,Gambiered Guangdong silk exhibited excellent antibacterial,antioxidant and UV protection properties;the antibacterial and antioxidant activities were attributable to the phenolic hydroxyl groups of condensed tannins present in silk.(2)The application of DC extracts to silk fabrics in weakly acidic medium conferred durable flame retardancy,durable antibacterial activity and oxidation resistance to silk fabric.Nevertheless,the silk fabrics treated with DC extracts at various concentrations had a reddish brown appearance from pale to dark,poor rub fastness and terrible light fastness.(3)The silk fabrics treated with DC extracts displayed dark colors after the post-mordanting with ferrous and ferric salts,showed dark reddish brown colors after the post-mordanting with titanium sulfate,and had no evident change in color hue after the post-mordanting with aluminum sulfate,potassium fluotitanate and potassium flurozate.The post-mordanting imparted more different colors to silk fabric,remarkably improved the rub and light color fastness of silk fabric,and increased the flame retardancy of silk fabric to some extent.(4)After subjected to the polyethyleneimine treatment,the silk fabrics treated with DC extracts exhibited further enhanced flame retardancy,and improved color fastness.