Heft 68 LENZINGER BERICHTE - Dezember 1989 (A presentation at the 28th International Man-Made Pibres Congress, Dor nbirn/Austria, September 20-22, 1989) Dr. Ludwig Rebenfeld, TRIIPrinceton, Princeton, New Jersey, USA The Role of Fiber Physics and Chemistry in Textile Properties The textile process owes its enormous versatility to the iact that fabric properties tan be affected or manipulated either by selection of fiber type or by finishing treatments. The textile industry now has available a large number of fiber types that tan be selected on the basis of their Chemical and physical properties. The major categories of man-made textile fibers are based on a relatively smal l number of polymers, specifically cellulose, Polyester, Polyamide or nylon, acrylic, and polyolefin. Yet within each of these polymer types, it IS possible to produce a wide range of fibers by designing molecular structure and morphology, and also by controlling fiber dimensions, particularly crossectional shape and linear density or fineness. One might say that this approach to the design of fabric properties is based on fiber physics. There are also available many finishing treatments of textile fabrics, particularly those based on cotton and man-made cellulosi c fibers, to impart fabric properties such as water and soil repellency, crease resistance and durable press, dimensional stability, and a wide range of tactile and aesthetic characteri stics. This approach to the optimization of the Performance characteristi cs of textile materials is based primaril y on textile chemistry. Yet, as will be emphasized in this lecture, neither fiber physi cs nor textile chemistry alone will achieve optimal fabric Perfor mance, the two approaches must be used cooperatively. Die Vielseitigkei t des Textilprozesses ist zurückführbar auf die Tatsache, daß Textileigenschaften sowohl durch Fasereigenschaften als auch durch Avivagebehandlungen beeinflußt werden können. Der Textilindu- strie stehen viele Fasertypen zur Verfügung. Obwohl nur wenige Poly- mertypen. wie zum Belspiel Cellulose, Polyester, Polyamide, Polyacryl und Polyolefin, benützt werden, besteht die Möglichkeit, die Eigen- schaften der Faser durch Anderungen der Molekularstruktur und M or- phologie über einen breiten Bereich zu modifizieren, Die Dimensionen der Fasern, z.B. der Durchmesser und der Faserquerschnitt, haben ebenfalls ei nen wichtigen Einfluß. Man könnte diesen Weg zur Beherr- schung der Textileigenschaften als die Methode der Faserphysik be- zeichnen Die Möglichkeit der Optimierung der Textileigenschaften, hauptsäch- lich für Cellulosefasern, besteht auch durch Textilveredlung. Wasser- und schmutzabstoßende Eigenschaften, Formbeständigkeit, Knitterfe- stigkeit, bügelfreie und andere Eigenschaften können durch Avivage- behandlungen erreicht werden. Di e Textilch emie bietet also ebenfalls einen vielseitigen Weg zu Textilien mit Hochleistungseigenschaft en. Die Textilche mie muß jedoch in Verbindung mit der Faserphysik betrachtet werden. htroduction The textile pro cess owes its enormous versatility to the fact that fabric properties tan be affected or manipulated in many different ways. At the very least, the physical properties of textiles depend on the inherent properties of the individual component fibers, on the geometric arrangement of the fibers in the yarns and fabrics, and on a wide r ange of mechanical and Chemical finishing treatments to which textile fabrics are normally subjected. In the design of fabrics with desired functional and aesthetic properties, it is necessary to consider all of these factors, and to understand the subtle interrelationships among them. Inherent Fiber Properties A convenient and useful classification of fiber properties is shown in table 1. In addition to the two principal natura1 fibers, cotton and wool, the te xtile industry now has available a large 14 number of man-made fibers that tan be selected on the basis of their geometric, physical, and Chemical properties. There are several varieties and types of both cotton and wool, so that it is possible to have some Variation in their properties, but these are generally restricted to geometric characteristics and are limited ovE?r narrow ranges. In the case of man-made fibers, only of geometric characteristics but also of physical and Chemical properties. This is achieved by selection of polymer type and by design of molecular structure and morphology through control of processing conditions. Table 1: Classification f fiber pmperties Classification of Fiber Properties Geometrlc Physical Chemical Length average vakJe dislribution Cross seclion area average value distriwtion shape Crimp 1requency fcmn ChXity linear bulk Thermal melting point transitions conductivity decompoaition Optical birefringence refractive Index luster and color Ek!,iCd ,eSlStlVlly dielectric constanl Response to ecids alkalies oxidalion reduction heai Sorption rnoisI”re dyes olher chemicals Swelling anisotropy Surface friction roughness Meohanlcel lenslon compreesion torsion bending shear lt is noteworthy that the major categories of man-made fibers are based on a relatively small number of polymer types, specifically cellulose, Polyester, Polyamide, acrylic, and poly- olefin. Yet, due the versatility of man-made fiber production technologies, it is possible to make available fibers for the textile iridustry that cover wide ranges in all of the principal properties. Karn and Fabric Structure The functional and aesthetic properties of textiles are strongly dependent on the geometric arrangement of the component fibers in the yarn and on the geometric arrangement of the yarns in the fabric. In spun yarns, such factors as the degree of fiber parallelization, the twist level, and hairiness will strongly influence yarn strength, bending rigidity, b ulkiness an d other physical properties that will affect fabric Perf ormance. Also in continuous filament yarns, the arrangement of the filaments i n the yarn structure will influence the ultimate characteristics of the fabric. Similarly, the geometric arrangement of the yarns in the fabric, i.e.,the weave Pattern and knit construction, will affect fabric Performance. In nonwovens, the geometric arrangement of the fibers not only in the plane of the fabric but also in the transverse direction, as well as the nature of the interfiber bonding mechanism, will determine fabric properties. lt is irnportant to understand that any given fibe r type, with its unique combination of inherent geometric, physical and Chemical properties, tan be used to produce fabrics with a wide range of performante characteristics by manipulation of the textile processing conditions that control the geometric rrangement alf fibers in yarns and of yarns in fabrics.
