Finishing Of Silk Fabrics With The Treatment Of Low-temperature Oxygen Plasma And Chitosan

Silk fabric has attracted much attention as its grace luster, soft handle, lightsome andelegant style, health benefits and excellent wearing comfort. But in dress process，there areshortcomings of silk fabric such as bad elasticity, easy to wrinkle, easy to yellowing, poorantibacterial properties，easy to fluffing and so on which largely limit its adhibition. Whilethe material life is becoming richer and richer, ecological and health problems have be-come a widespread focus today, it’s a tide to study and produce silk textiles which benefitsto ecology and health. So to develop silk fabric with good crease resistance and antibac-terial properties has a broad market prospect. In recent years, with the improvement ofperformance requirements of textiles, crease resistant and antibacterial finishing of real silkfabric has turned into a trend in finishing technology.For the poor wrinkle-resistant and poor antibacterial properties, silk fabrics weretreated with low-temperature oxygen plasma before coordinated by chitosan-citric acid so-lution through double-dip-double-nip. Take mechanical property and whiteness test to thefinished fabrics. The results showed that the crease recovery angles improved about50o.The breaking strength and the whiteness declined slightly. Washing resistance was alsoimproved significantly and finishing effect was more lasting and stable.The factors influenced on finishing results were studied and a good anti-crease finish-ing effect was obtained when plasma RF power at80W, treatment time at5min.Weightlessness rate tended to increase with plasma processing time which should be con-trolled well in the practical application in order to avoid the etching effect and damage onthe surface of fabric material.In chitosan solution finishing of silk fabrics, chose chitosan concentration, curing tem-perature and curing time as influencing factors in three levels respectively and took creaserecovery angle, breaking strength and whiteness as evaluation index, undergoing singlefactor experiment and orthogonal experiment respectively. The optimized parameters ofplasma-chitosan process of silk crease resistant finishing were: chitosan concentration0.5%, curing temperature120℃, curing time5min. The antibacterial results of finished silk fabrics respectively: to staphylococcus aureuswas91.6%, to e. coli was93.2%, to Candida albicans was74.1%; After30times of wash-ing, silk fabric still maintained good antibacterial rate to staphylococcus aureus and e. coliwhich was about90%, but poor water resistance of Candida albicans.Through experimental comparison of scanning electron microscopy (SEM) resultamong the original silk fabrics, silk fabrics treated by plasma and by plasma-chitosan, the analysis showed: after low-temprature plasma treatment, silk fiber’s surface became rough due to the etching effect and fiber surface got activation effect. After chitosan finishing of silk fabrics, chitosan was covalent cross-linked with fabricsurface which made yarn of interwoven point was difficult to slip, so the crease recovery angles increased.X-ray diffraction (XRD) experiment was carried out between original silk fabric andfabric treated by plasma and chiotosan. As you can see from diffraction analysis pictures,XRD curves shape were similar and the main characteristic peak closed to the oppositediffraction angle, indicating that the aggregation structure of silk fabric occurred no fun-damental changes when chitosan grafted. And the intensity of XRD curves of silk fabricgrafted chitosan was slightly lower than the original one, which was due to the chitosanmolecule to infiltrate fiber internal amorphous region and occurred grafting reaction, wea-kening the hydrogen bonding interaction between fibroin macromolecules, destroying thewell arrayed molecular chain segments, making silk fiber structure relaxation. So the de-gree of crystallinity of the plasma-chitosan combined crystallinity silk fabric was reduced.Fourier transformation infrared spectrum analysis (FTIR) showed that graft reactiontook place between chitosan and silk fiber, making N element association on silk fibers,but the plasma treatment process introduced no groups in silk fiber macromolecule. Thisshowed that after plasma and chitosan finishing, some disordered structure of macromole-cular chain within silk fibroin presented the trend of β and chitosan molecules combinedwith silk fabric by plasma activation and esterification bridging of citric acid. This conclu-sion was consistent with the scanning electron microscopy (SEM) analysis.After plasma-chitosan treatment, silk fabrics’ physical and mechanical properties and antibacterial properties were greatly improved, as well as its wearability greatly satisfiedpeople’s pursuit of luxury, comfort, and special function of silk fabrics. This experimentprovided the direction for the further exploring and utilization of silk products and im-provement of its wearability.