Study On Preparation, Structure And Properties Of Wool Fiber With Antibacterial Function

With the development of society and improvement of living standard, the demand for functional textiles is getting higher and higher, which, to some extent, promotes the development of functional textiles. In the future of textile production, functionality will become the decisive factor in development. Natural wool fiber has been widely used for long in human being history. Being lighter, warmer, softer and smoother than other fibers, wool has been known as superior textile material. But natural wool fiber is not antibacterial and wool textiles can provide living space for bacteria, which is harmful to health and environment. Along with their aspiration for new style, people choose functional wool textiles with more favor. Therefore, it becomes an important challenge to make wool fiber antibacterial. Moreover, China is among the main countries for wool production in the world , which provides good opportunities to develop antibacterial wool products.In this paper, the effect of ultraviolet (UV) irradiation on the structures and properties of wool fiber were studied. The mechanism of surface modification of wool fiber by UV irradiation was discussed. Silver-loading nano-SiO2 antibacterial agent (SLS) and chitosan crosslinked Ag-loading nano-SiO2 antibacterial agent (CCTS-SLS) were prepared and discussed in detail with respect to their molecular structures and properties. Antibacterial wool fibers were obtained by grafting SLS and CCTS-SLS antibacterial functional materials. The structures and properties of antibacterial wool fibers and the grafting mechanisms of SLS and CCTS-SLS on wool fiber surfaces were systematically investigated.The morphologies of the samples were observed by scanning electron microscopy (SEM). The structures of specimens were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), infrared spectroscopy (IR) and Fourier transformation Raman spectrometry (FTR). The contents of silver were measured with inductively coupled plasma spectrometry (ICPS) and X-ray photoelectron spectroscopy (XPS). The antibacterial properties of all specimens were tested using alive-bacteria-counting, minimum inhibitory concentration method (MIC), or flask-shaking method. The thermal stability, mechanical properties and friction behaviors were also measured.The main conclusions are as follows:(1) With the increase of UV irradiation time, the crystallinity of wool fiber was continuously declined, along with the increase in the degree of disorder in the molecular structure. Moreover, the force, tensile strength and elongation were decreased. The some active free radicals and dangling bonds were formed on the surface of wool fiber during UV irradiation along with the introduction of a lot of new groups, which can be used for grafting with antibacterial agents.(2) The SLS antibacterial agent was narrowly distributed spherical particles with the mean particle size of 60 nm. They exhibited excellent release property of silver ions and good antibacterial performance against E. coil and S. aureus.(3) The antibacterial wool fiber grafted with SLS under optimized conditions had an antibacterial layer of 200 nm in thickness, which was formed on the wool fiber surface by covalent bonding between SLS and wool fiber. The antibacterial wool fiber showed excellent friction performance and wash resistance property. The improved degree of disorder in the molecular structure during the modification resulted in the good mechanical property and thermal stability. The SLS-wool it was longer and thinner with higher crimp recovery and crimp elasticity, which may be more suitable for processing on conventional textile machinery.(4) The morphologies of CCTS-SLS particles were amorphous, layered and embedded with mean particle sizes of 110 nm, which had the characteristic FTIR bands occurring in CTS and SLS. SLS particles were coated by CCTS layer with the thickness of 4 nm. In addition, the content of silver in CCTS-SLS was similar to that of SLS. CCTS-SLS had excellent release property and antibacterial performance, the same as SLS.(5) The antibacterial wool fiber grafted with CCTS-SLS had good hand-feeling, thus fully exhibiting the excellent characters of wool fibers. The color was closed to that of original wool fiber. CCTS-SLS particles were grafted by covalent bonding on the surface of wool fiber. The degree of order in the molecular structure was similar to that of original wool fiber. Compared with original wool fiber, CCTS-SLS-wool was improved in mechanical, frictional, thermal and antibacterial wash-resistant properties.The surface modification of natural wool fiber was realized using the method of UV radiation. Nano-antibacterial functional materials / fiber interfacial layer came into being in the form of chemical bond combination by grafting reaction, which was clearly different from traditional physical adsorption. This kind of antibacterial functionalization shows many advantages. Firstly, it realizes lasting antibacterial effect, excellent mechanical property and low cost; Secondly, it increases the grade of wool fiber in application and function; Thirdly, it improves the spinnability, serviceability and functionality of wool, thus greatly increasing added value. Finally, it prevents the emissions of contaminated aqueous solution in traditional treatment process and therefore conducive to energy saving, emission reduction and environmental protection. The surface functional modification mechanism of natural wool fiber lays the foundation of the interface structural model between natural fiber and nano-function materials, which, plays an important role of theoretical guidance for the design and manufacture of high-performance fibers.