| Meta-Aramid Fiber
Nomex
Conex
|
Meta-aramids are perhaps the best known and most widely used specialized fibers. They are valued for their combination of heat resistance and strength, at reasonable cost. In addition they don't ignite, melt or drip. Compared to commodity fibers, meta-aramids offer better long-term retention of mechanical properties at elevated temperatures. |
| Para-Aramid Fiber
Kevlar
Technora
Twaron
|
Due to their highly oriented, rigid molecular structure, para-aramid fibers have very high tenacity, high tensile modulus and high heat resistance. With similar operating temperatures to meta-aramid fibers, they have 3-7 times higher strength and modulus, making them ideal for reinforcement and protective type application. |
| Areal Density |
Mass per Unit Area. Used in weight comparison of composite materials. |
| Breaking Tenacity |
The tensile stress at rupture of a specimen (fiber, filament, yarn, cord, or similar structure) expressed as newtons per tex, grams-force per tex, or grams-force per denier. The breaking tenacity is calculated from the breaking load and linear density of the unstrained specimen, or obtained directly from tensile testing machines which can be suitably adjusted to indicate tenacity instead of breaking load for specimens of known linear density. Breaking tenacity expressed in grams-force per tex is numerically equal to breaking length expressed in kilometers. |
| Burst Strength |
1. The ability of a material to resist rupture by pressure. 2. The force required to rupture a fabric by distending it with a force applied at right angles to the plane of the fabric under specified conditions. Burst strength is a measure widely used for knit fabrics, nonwoven fabrics, and felts where the constructions do not lend themselves to tensile tests. The two basic types of burst tests are the inflated diaphragm method and the ball-burst method. |
| Denier |
A weight-per-unit-length measure of any linear material. Officially, it is the number of unit weights of 0.05 grams per 450-meter length. This is numerically equal to the weight in grams of 9,000 meters of the material. Denier is a direct numbering system in which the lower numbers represent the finer sizes and the higher numbers the coarser sizes. In the U.S., the denier system is used for numbering filament yarns (except glass), manufactured fiber staple (but not spun yarns), and tow. In most countries outside the U.S., the denier system has been replaced by the tex system. |
| Fill
(Also Woof, Weft or Transverse)
|
In a woven fabric, the yarn running from selvage to selvage at right angles to the warp. Each crosswise length is called a pick. In the weaving process, the fill yarn is carried by the shuttle or other type of yarn carrier. |
| Instron Tensile Tester |
A high precision electronic test instrument designed for testing a variety of materials under a broad range of test conditions. It is used to measure and chart the load-elongation properties of fibers, yarns, fabrics, webbings, plastics, films, rubber, leather, paper, etc. May also be used to measure such properties as tear resistance and resistance to compression |
| Linear Density |
Mass per unit length expressed as grams per centimeter, pounds per foot, or equivalent units. It is the quotient obtained by dividing the mass of a fiber or yarn by its length. |
| Liquid Crystal Polymer
Vectran
|
Vectran is a high-performance, thermoplastic, multifilament yarn, melt-spun from liquid crystal polymer. It has exceptional strength and rigidity and is five times stronger than steel and 10 times stronger than aluminum. The combination of high strength, lack of creep, low moisture absorption, negative coefficient of thermal expansion, excellent chemical resistance and good property retention over a broad temperature range make it a good candidate for ropes and cables, electronics, composites and general industrial use. |
| Machine Direction
Also Warp
|
The long direction within the plane of the fabric, i.e., the direction in which the fabric is being produced by the machine. |
| Modulus |
The ratios of change in stress to change in strain following the removal of crimp from the material being tested; i.e., the ratio of the stress expressed in either force per unit linear density or force per unit area of the original specimen, and the strain expressed as either a fraction of the original length or percentage elongation. |
| Packing Efficiency |
Theoretical solid volume divided by actual packed volume and usually expressed as a percentage. Practical upper limit with hydraulic pressure assistance would be ~ 80%. |
| PBO
Zylon
|
Polyphenylenebenzobisoxazole (PBO) is another new entrant to the high-performance organic fibers market, and one that holds great promise. Toyobo's Zylon is the only PBO fiber in production, and commercial quantities have only recently come to market. PBO has outstanding thermal properties and almost twice the tensile strength of conventional para-aramid fibers. Its high modulus makes it an excellent candidate for composites reinforcement and structural fabric. Its high Limiting Oxygen Index (LOI) gives PBO more than twice the flame retardant properties of meta-aramid fibers. |
| Peel Adhesion |
The force required to delaminate a structure or to separate the surface
layer from a substrate. Peel adhesion is the unusual
measure of the strength of the bond between a fabric
and a coating, for instance. |
| Permeability |
The state or quality of being penetrable by fluids or gases. Units are usually normalized for comparison to other materials; volume/unit area @ 1 atm differential pressure through a given thickness |
| Polyethylene, High-Density (HDPE)
Spectra
Dy-neema
|
HDPE fibers offer strength similar to that of para-aramids. HDPE fibers are known as Dyneema throughout the world, except in North America, where the process is licensed to AlliedSignal and is known as Spectra. Light in weight, the fiber has a specific gravity of only 0.97. Tough yet lightweight products can be made, including rope and cordage that floats as well as soft and semi-rigid body armor, and cut-resistant materials. |
| Polyimide Film
Kapton
Kinel
Upilex
Upimol
Vespel
|
Normally infusible, colored (often amber) high performance polymers with predominantly aromatic molecules of high thermal stability. They have excellent high temperature properties and radiation resistance, inherently low flammability and smoke emission, low creep and high wear resistance. They have moderately high water absorption and are prone to hydrolysis and attack by alkalis and concentrated acids. A widely used form is Kapton® film, made in thicknesses from 0.008 to 0.125mm. It has been used successfully in field applications where the environmental temperatures were as low as -269°C and as high as 400°C. Polyimide film can be easily fabricated by a wide variety of techniques, including die cutting, punching and thermoforming. Applications include electrical insulation and thermal insulation. |
| Scrim |
1. A lightweight, open-weave, coarse fabric; the best qualities are made with two-ply yarns. Cotton scrim usually comes in white, cream, or ecru and is used for window curtains and as backing for carpets.
2. Fabric with open construction used as back fabric in the production of coated or laminated fabrics.
|
| Selvage Or Selvedge |
The narrow edge of woven fabric that runs parallel to the warp. It is made with stronger yarns in a tighter construction than the body of the fabric to prevent raveling. A fast selvage encloses all or part of the picks, and a selvage is not fast when the filling threads are cut at the fabric edge after every pick. |
| Tenacity |
The tensile stress when expressed as force per unit linear density of the unstrained specimen (e.g., grams-force per denier or newtons per tex). |
| Tensile Strength |
1. In general, the strength shown by a specimen subjected to tension as distinct from torsion, compression, or shear. 2. Specifically, the maximum tensile stress expressed in force per unit cross-sectional area of the unstrained specimen, e.g., kilograms per square millimeter, pounds per square inch. |
| Tex |
1. A unit for expressing liner density, equal to the weight in grams of 1 kilometer of yarn, filament, fiber, or other textile strand.
2. The system of yarn numbering based on the use of tex units.
|
| Urethane |
The name of a group of organic chemical compounds or resins built from isocyanate, a very reactive-material that liberates gas during reaction to produce foams of various types. Two types of compounds that react with isocyanate to form foam are polyesters and polyethers. Polyurethanes are used for foams and in other compounds in fiber form. The polyester variety should not be confused with polyester fibers. |
| Warp
Also Machine Direction
|
1. The set of yarn in all woven fabrics, that runs lengthwise and parallel to the selvage and is interwoven with the filling.
2. The sheet of yarns wound together on a beam for the purpose of weaving or warp knitting.
|
| Yarn Number |
A relative measure of the fineness of yarns. Two classes of systems are in
use:
(1) Direct yarn number (equal to linear density) is the mass per unit length of yarn. This is used for manufactured filament yarns.
(2) Indirect yarn number (equal to the reciprocal of linear density) is the length per unit mass of yarn. This system is used for cotton, linen, and wool-type spun yarns.
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