Effect Of Organic UV Absorber/Nanoparticle Feeding On Silk Dyeing Performance Of Silkworm

Silk has many excellent properties,but it has disadvantages such as poor UV resistance and yellowing,etc.The addition of new functional substances to silkworms is expected to obtain new functional silk protein/functional composites from the source.Existing studies have shown that the addition of UV absorbers to silkworms can improve the UV resistance of silk,the addition of nanoparticles to silkworms can improve the mechanical properties of silk,and the addition of substances will have a certain effect on the secondary structure and crystalline structure of silk.In this study,we propose to investigate the dyeing properties of silk fibers modified by the addition of2%mass fraction of organic UV absorbers（2,2’,4,4’-tetrahydroxybenzophenone,4-dimethylaminobenzoic acid and 3,4-dimethoxycinnamic acid）and nanoparticles（nano-Ti O₂,nano-Cu O and nano-Cu）at different mass to silkworms based on previous studies.The effects of the addition of UV absorbers on the antioxidant properties of modified silk and the effect of UV shielding agents on the color stability of silk fibers against sunlight were investigated in order to provide a more complete study of the additive feeding method and also to provide a reference for the practical application of modified silk.The conclusions obtained from this study are as follows:（1）The chemical structure of the UV absorber and the change of the secondary structure of silk caused by the addition of food can affect the dyeing performance of silk.The results showed that the dyeing rate and dyeing color depth（K/S value）of the acid and reactive dyestuff on the silk fibers modified by the addition of food were higher than those of the blank group,and the addition of the UV absorber selected in this paper can significantly improve the dyeing performance and washing color stability of silk fibers.（2）The 2%mass fraction of nanoparticles combined with mulberry leaf feeding can enhance the dyeing performance and washing color stability of silk fibers.In contrast,0.1%mass fraction of nanoparticles had less effect on the dyeing performance,indicating that the concentration of nanoparticle feeding affected the structure of silk fibers to different degrees,thus affecting the dyeing performance of silk fibers.（3）The dyeing kinetics and thermodynamic mechanism of Acid OrangeⅡon silk fibers were investigated,and the results showed that the dyeing process of Acid OrangeⅡon silk fibers of all groups was in accordance with the quasi-secondary adsorption kinetic equation,which was Langmuir-type adsorption,and the dyeing process was exothermic,so the lower temperature was more suitable for dyeing silk fibers.The adsorption equilibrium saturation amounts q_e at 60℃were 0.28 g/kg,0.72 g/kg and0.75 g/kg higher than those of the blank group,and the maximum values q_m of the adsorbed dyes were 12.02 g/kg,17.30 g/kg and 19.42 g/kg higher than those of the blank group,respectively.The q_e of 2%nano-Ti O₂ and nano-Cu O additive modified silk fibers were 0.04 g/kg and 0.95 g/kg higher than the blank group,and the q_m were5.31 g/kg and 14.58 g/kg higher than the blank group,respectively.（4）All the three UV absorbers could enter the silk through additive feeding,and the leaching in ethanol was limited.The antioxidant results showed that the ability of 1g of additive-modified silk to scavenge 2,2-biphenyl-1-picrylhydrazyl（DPPH）radicals was 1.2 times,1.6 times and 1.1 times higher than that of the blank group silk,respectively;the ability of scavenging 2,2-biazo-bis（3-ethyl-benzothiazole-6-sulfonic acid）diammonium salt（ABTS）radicals was 2.5 times,2.3 times and 1.2 times higher than that of the blank group silk,respectively.（5）Ultraviolet shielding agent additive feeding of brood silkworms can significantly improve the color stability of silk fibers against sunlight.