Volume 4, Issue 1, Summer 2004 Application of Nanotechnology for high performance textiles Lei Qian Institute of Textile Technology College of Textiles North Carolina State University Juan P. Hinestroza TECS, College of Textiles North Carolina State University ABSTRACT This paper summarizes the recent development of nanotechnology in textile areas including textile formation and textile finishing. Details on two major technical aspects, using nanosize entities and employing specific techniques to create nanosize structure inside textile materials, have been elucidated. A number of nanosize fillers and their resultant performances have been reviewed. Particularly, nanolayer assembly, a new concept of textile surface coating, has been introduced. At the end, perspectives regarding future development of nanotechnology for smart and intelligent textiles have been addressed. Keywords: Nanotechnology, nanosize fillers, nanosize structure, nanoparticles, cellular structure Introduction nanosize particles in a precise and controlled manner in order to build materials with a Nanotechnology is an emerging fundamentally new organization and novel interdisciplinary technology that has been properties. The embryo of nanotechnology is booming in many areas during the recent “atomic assembly”, which was first publicly decade, including materials science, articulated in 1959 by physicist Richard mechanics, electronics, optics, medicine, Feynman. Nanotechnology is called a plastics, energy, electronics, and aerospace. “bottom up” technology by which bulk Its profound societal impact has been materials can be built precisely in tiny considered as the huge momentum to usher building blocks, different from the in a second industrial revolution.1,2 traditional manufacture ― “top down” technology. Therefore, resultant materials The “nano” in nanotechnolgy comes have fewer defects and higher quality. from the Greek word “nanos” that means dwarf. Scientists use this prefix to indicate The fundamentals of nanotechnology lie 10-9 or one-billionth. One nanometer is one- in the fact that properties of substances billionth meter that is about 100,000 times dramatically change when their size is smaller than the diameter of a single human reduced to the nanometer range. When a hair. Nanotechnology endeavors are aimed bulk material is divided into small size at manipulating atoms, molecules and particles with one or more dimension Article Designation: Scholarly 1JTATM Volume 4, Issue 1,Summer 2004 (length, width, or thickness) in the The main function of nanosize fillers is nanometer range or even smaller, the to increase the mechanical strength and individual particles exhibit unexpected improve the physical properties such as properties, different from those of the bulk conductivity and antistatic behaviors. Due material. It is known that atoms and to their large surface area, these nanofillers molecules possess totally different behaviors have a better interaction with polymer than those of bulk materials; while the matrices. Being in the nanometer range, the properties of the former are described by fillers might interfere with polymer chain quantum mechanics, the properties of the movement and thus reduce the chain latter are governed by classic mechanics. mobility. Being evenly distributed in Between these two distinct domains, the polymer matrices, nanoparticles can carry nanometer range is a murky threshold for load and increase the toughness and abrasion the transition of a material’s behavior. For resistance; nanofibers can transfer stress example, ceramics, which normally are away from polymer matrices and enhance brittle, can easily be made deformable when tensile strength of composite fibers. their grain size is reduced to the low Additional physical and chemical nanometer range. A gold particle of 1 nm performances imparted to composite fibers across shows red color. Moreover, a small vary with specific properties of the amount of nanosize species can interfere nanofillers used. Distribution of nanofillers with matrix polymer that is usually in the in polymer matrices through mechanical and similar size range, bringing up the chemical approaches is one of the important performance of resultant system to an aspects leading to high quality of unprecedented level. These are the reasons nanostructured composite fibers. Although why nanotechnology has attracted large some of the filler particles such as clay, amounts of federal funding, research activity metal oxides, carbon black have previously and media attention. been used as microfillers in composite materials for decades, reducing their size The textile industry has already impacted into nanometer range have resulted in higher by nanotechnology. Research involving performances and generated new market nanotechnology to improve performances or interest. to create unprecedented functions of textile materials are flourishing. These research Carbon Nanofibers and Carbon endeavors are mainly focused on using Nanoparticles nanosize substances and generating nanostructures during manufacturing and Carbon nanofibers and carbon black finishing processes. nanoparticles are among the most commonly used nanosize filling materials3,4. Carbon Nanotechology in Manufacturing nanofibers can effectively increase the Composite Fibers tensile strength of composite fibers due to its high aspect ratio, while carbon black Nano-structured composite fibers are in nanoparticles can improve their abrasion the area where we see the early blooming of resistance and toughness. Both of them have nanotechnology, while many other high chemical resistance and electric applications are still way off future. Those conductivity. Several fiber-forming composite fibers employ nanosize fillers polymers used as matrices have been such as nanoparticles (clay, metal oxides, investigated including polyester, nylon and carbon black), graphite nanofibers (GNF) polyethylene with the weight of the filler and carbon nanotubes (CNT). Besides, from 5% to 20%5,6. nano-structured composite fibers can be generated through foam-forming process, other than using nanosize fillers. Article Designation: Scholarly 2JTATM Volume 4, Issue 1,Summer 2004 into polyproprene before it is extruded. As a result, polyproprene with clay nanoparticles by weight percentage of 5% can be colored Clay Nanoparticles by acid dyes and disperse dyes.9 Clay nanoparticles or nanoflakes are Metal Oxide Nanoparticles composed of several types of hydrous aluminosilicates. Each type differs in Nanosize particles of TiO2, Al2O3, ZnO, chemical composition and crystal structure. and MgO are a group of metal oxides that Clay nanoparticles possess electrical, heat possess photocatalytic ability, electrical and chemical resistance and an ability of conductivity, UV absorption and photo- blocking UV light. Therefore, composite oxidizing capacity against chemical and fibers reinforced with clay nanoparticles biological species. Intensive researches exhibit flame retardant, anti-UV and anti- involving the nanoparticles of metal oxides corrosive behaviors. For example, have been focusing on antimicrobial, self- nanoparticles of montmorillonite, one of decontaminating and UV blocking functions most commonly used clay, have been for both military protection gears and applied as UV blocker in nylon composite civilian health products 6. Nylon fiber filled fiber. The mechanical properties with a clay with ZnO nanoparticles can provide UV mass fraction of only 5 % exhibits a 40% shielding function and reducing static higher tensile strength, 68% greater tensile electricity of nylon fiber. A composite fiber with nanoparticle of TiO2/ MgO can provide self-sterilizing function 18. Carbon Nanotubes Carbon nanotube (CNT) is one of the most promising building blocks existing. Its higher strength and high electrical conductivity are not comparable by carbon nanofibers. CNT consists of tiny shell(s) of graphite rolled up into a cylinder(s). With 100 times the tensile strength of steel at one- sixth weight, thermal conductivity better than all but the purest diamond, and modulus, 60% higher flexural strength, and electrical conductivity similar to copper, but a 126% increased flexural modulus7. In with the ability to carry much higher addition, the heat distortion temperature currents, CNT seems to be a wonder (HDT) increased from 65oC to 152oC. material. Nanosize clay flakes are arranged densely and alternately than the therefore, the Generally, CNTs are classified into composite material has barrier performance single-walled carbon nanotube (SWNT) and to water, chemicals or other harmful multi-walled carbon nanotube (MWNT). species.7,8 They are usually made by carbon-arc discharge, laser ablation of carbon, or Another function of clay nanoparticles is chemical vapor deposition. The potential to introduce dye-attracting sites and creating applications of CNTs include conductive dye-holding space in polyproprene fibers, and high-strength composite fibers, energy storage and energy conversion devices, known as non-dyeable fiber due to its 10,11 structural compactness and lack of dye- sensors, and field emission displays. attracting sites. Nanoparticles of montmorillonite are modified with One of the successful examples of CNT quaternary ammonium salt and then mixed composite fiber is the SWNT- polyvinyl Article Designation: Scholarly 3JTATM Volume 4, Issue 1,Summer 2004 alcohol fiber with fiber diameters in One of the approaches is to make use of micrometer range produced by using a thermodynamic