Grape skins and seeds rich in polyphenolic compounds are lowvalue byproducts from the wine-making. The valorization of such byproducts is of great significance. This work presented a novel application of grape seed proanthocyanidins (GSPs) in the dyeing and flame-retardant and antibacterial treatment of silk. The study on adsorption isotherms revealed that multiple interactions occurred between GSPs and silk, including electrovalent bonding, hydrogen bonding, and van der Waals forces. The color depth of silk mainly depended on temperature and GSP concentration. Dyed silk had acceptable color fastness to washing, rubbing, and perspiration. Postmordanting could improve light fastness. Changes in the tensile strength and flexural rigidity of dyed silk were in an acceptable range. A low concentration of GSPs imparted a durable antibacterial function to silk. The biggest highlight of this study was the improved flame retardancy of silk caused by GSP dyeing. GSPs increased the thermal stability and charring ability of silk at high temperatures, and their flame-retardant action worked in the solid phase. Mordanting had no substantial impact on the flame-retardant and antibacterial functions of dyed silk. The present research reveals that the valorization of GSPs for silk processing is feasible.

Cotton has the shortcomings of having no antibacterial, antioxidant and ultraviolet (UV) protection properties, which are of great importance for health protection purposes. In the present study, grape seed extract (GSE) mainly composed of proanthocyanins (tannins) was employed to simultaneously import pale colors and the three aforementioned functions to cotton fabric. The tests on the application conditions of GSE showed that pH and GSE concentration had great impact on the color depth of cotton fabric, and the color hue of dyed fabric could be controlled in the absence of pH regulators due to the weakly acidic nature of GSE solution. The fabric dyed with 10%owf (on the weight of fabric) GSE exhibited an excellent inhibition effect towards Escherichia coli, whereas the one dyed with 20%owf GSE had high antioxidant activity of 97%. The fabric dyed with 5%owf GSE offered excellent UV protection. This study reveals that GSE can be used as a functional finishing agent for health protection in cotton textiles in addition to coloration capability.

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The functionalization of microcrystalline cellulose (MCC) is an important strategy for broadening its application fields. In the present work, MCC was functionalized by phosphorylation reaction with phytic acid (PA) for enhanced flame retardancy. The conditions of phosphorylation reaction including PA concentration, MCC/PA weight ratio and temperature were discussed, and the thermal degradation, heat release and char-forming properties of the resulting PA modified MCC were studied by thermogravimetric analysis and pyrolysis combustion flow calorimetry. The PA modified MCC, which was prepared at 90 °C, 50%PA and 1:3 weight ratio of MCC to PA, exhibited early thermal dehydration with rapid char formation as well as low heat release capability. This work suggests a novel strategy for the phosphorylation of cellulose using PA and reveals that the PA phosphorylated MCC can act as a promising flame retardant material.