Wednesday 26 February 2014

Synthetic Fibers and Fabrics Information


Polyamide synthetic fabric
Image Credit: HiTech Seals | Darco Southern | Mid-Mountain Materials

Fibers and fabrics play a large role in everyday applications. A fiber is a hair-like strand of material. They are the smallest visible unit of a fabric and are denoted by being extremely long in relation to their width (at least 100 times longer than it is wide). Fibers can be spun into yarn and made into fabrics.

Synthetic fibers are a subset of the larger area of textiles. Textiles can be natural or synthetic. Natural fibers include cotton, fur, wool, etc. Regenerated fibers are natural materials that have been processed into a fiber structure. Regenerated fibers such as cellulose and wood pulp are used to make materials such as rayon and acetate. Synthetic fibers are man made from chemicals. They are generally based on polymers and are stronger than natural and regenerated fibers.

Advantages
Disadvantages
Strong
Melt when hot
Thermoplastic
 Use petrol
Resistant to moths and fungi
Non-renewable
Abrasion-resistant
Can be an allergenic
Easy to care for

Low absorbency

Inexpensive

Easily available


 

Identification

It is often easy to identify what type of fiber or fabric a material is by look or touch alone. A variety of tests have been developed to aid in identifying materials. For more information please visit the Industrial Fabric Selection Guide.

How Synthetic Fibers and Fabrics are Made

 Most synthetic fibers go through a similar production process which includes four steps.

1. A chemical process, usually polymerization, prepares and combines the components for the fiber. Polymerization is the formation of macromolecules through repetition of basic units. Initially, the various components are solids and first must be converted to a liquid state to be extruded into fibers. The materials are chemically converted, dissolved, or melted, turning into a thick liquid.

Image Credit: CarletonUvideos

2. A spinning process produces the fiber by passing the thick liquid through a spinneret. A spinneret is a device with hundreds of holes of a specified diameter. The liquid is forced through the spinneret holes and comes out a string liquid filament. The hole in the spinneret determines the diameter of the filament, which is set by the application. The extrusion is dried to a continuous filament fiber.

Spinneret. Image Credit

3. A twisting process twists the filament fiber into a yarn. The filament falls vertically from the spinneret and is caught in a large vacuum nozzle. The vacuum force keeps tension on the line as it is wound around a bobbin.
4. The twisted yarn is packaged and sent to a textile mill.

For information on natural fiber manufacturing, please visit the Industrial Fabric Selection Guide.

Selection Criteria

GlobalSpec allows users to search and select synthetic fibers by several specifications, including end-product type, material properties, features, and applications.

End-Product Types for Synthetic Fibers and Fabrics

Synthetic fibers and synthetic fabrics consist of bulk fibers, yarns, woven cloth or other textile products manufactured from polymer-based materials such as polyamide (nylon), polyester, aramid, or other spun thermoplastics. The end-product is the form of the fiber/fabric when manufacturing is complete. Basic product types include: 
  • Fibers and monofilaments- Single fibers are called filaments and a monofilament is when a single continuous filament is rolled on a spool. A filament bunch is called a strand or end. Bulk chopped fibers or thin, continuous fiber filaments are used typically in composite reinforcement applications, flow-able insulation, or as the key component in woven fabrics, braids, knits, rope roving, or other specialty fabrics.
  • Roving- Roving is made of parallel filaments. Graphite rovings are referred to as tows. Rovings are marked by the number of filaments they contain. Tows are marked by the number of filaments with the most common graphite tows being 3K, 6K and 12K.
  • industrial yarnYarn- Yarn is made of continuous, often plied strands of natural or man-made fibers or filaments. The filament is then twisted to hold fibers together. Image Credit
  • Carded and needle punched, non-woven- Carded yarn has been through the card machine but has not been combed. Because they contain a range of fiber lengths they are low strength, low density, and low cost.
  • Braided products- Braided fabrics are made by crossing a number of strands diagonally so each strand passed alternating over or under one or more of the other strands. These products are used for tubular composite structures, thermal insulation, and in other applications. Image Credit
  • Rope and cordage- Cord is formed by twisting together two or more plied yarns. It can also be defined as a rib on the surface of a fabric. Rope is a heavier and stronger cord. It is made from either natural or synthetic fibers and is available in a wide range of diameters. Rope is made in a two step process; first the yarns are twisted together to form strands and then the strands are twisted together in the opposite direction to form the rope. The alternating direction of the twist at different stages of the rope assembly makes the rope twist stable and resistance to kinks.
  • Webbing- Webbing is strong, narrow fabric that has been closely woven. They are available in a variety of weaves and often found in straps that have to withstand strain (belt, seat belts, suspenders, etc.) Webbing includes ribbons, strapping, and tape. Image Credit
  • Blankets or batts-Blankets or batts (batting) are made of thick layers of woven and/or non-woven fabric sheets. Battings are webs of loose fibers that have usually been carded. Battings are sold in sheets or rolls and used for warm linings and comforter stuffings.
  • Sleeves or wraps- Sleeves or wraps (sleeving) are flexible, fibrous refractory products for insulating pipes, tubes, ducts, and other process components. Image Credit
  • Thread- Synthetic thread includes both monofilaments and multi-fiber filament; a slender, strong strand or cord. Most threads are made by plying and twisting yarns. There is a large variety of yarns available for many different industrial applications.  

Material Specifications

GlobalSpec allows users to search for synthetic fibers and fabric by the material property, type of material, and features such as blended fiber structures and coated or sized fibers.

Material Properties

In order to determine the polymer to use, key properties of polymer should be identified. These properties include: 
  • Composition and structure- The type of polymer, the amount/length of side chains, and the shape of the polymer. The shape and amount/length of side chains plays an important role in the strength of the polymer.
  • Melting point- The temperature at which the polymer begins to melt. Melt strength is a property which indicates the polymer's ability to withstand drawing without breaking. This is improved with the presence of high molecular weight tail or long chain branches.
  • Modulus- The ability of a material to resist deformation. The property is usually expressed as the ratio of stress exerted on the sample to the amount of deformation.
  • Elasticity and recovery from strain- The elastic limit is the stress at which the uniaxial stress-strain curve becomes nonlinear due to shear yielding or crazing. Shear yielding is the irreversible slipping of molecule chairs and crazing is the formation of low density, crack-like volumes which scatter light (this makes the polymer look white).
  • Tensile- These properties are the most important indication of strength and stiffness of the material. They determine the force necessary to pull the specimen apart, and the deformation before breaking. The tensile modulus is a measure of stiffness calculated based on measured force.
  • Density- The weight per unit volume. Density affects physical properties like stiffness, impact strength, and optical properties.
  • Moisture absorption- The amount of moisture a fiber will absorb from the air at a standard condition of 70°F and a relative humidity of 65%.
  • Dye-ability- The ability of the polymer to absorb and hold on to a dye.
  • Comfort- How the material feels to the user. If the fiber or fabric is going to be used in apparel then the comfort stretch (freedom of movement when wearing the fabric), phase change ability, and hydrophobic nature should be considered.  

Material Type

Synthetic fibers and fabrics are all made from a type of polymer but they each have unique properties and characteristics making them useful for specific applications. The fibers and fabrics may include a variety of materials and may feature a blended, fibrous structure produced by copolymerization. Synthetic fibers that are made of elastomers, fluoropolymers, glass, and fiberglass are also commonly available. Material types for synthetic fibers and synthetic fabrics include:
Fiber Name
Description
Application
Advantages
Disadvantages
Acetate and
triacetate fibers
Acetate
This type of fiber is known as a regenerated man made material.  Acetate is derived from cellulose by reacting purified cellulose from wood pulp with acetic acid and acetic anhydride in the presence of sulfuric acid. Both materials are heat resistant below their melting point.
The largest volume application for acetate fiber is cigarette filters, but it is also widely used in women's wear.The luxurious fibers are available in a wide range of colors and lusters.
They are fast drying are resistant to moths and mildew. Triacetate has excellent sunlight resistance but acetate does not. They are shrink-resistant and wrinkle-resistant.
Disadvantages include poor abrasion resistance, susceptible to attack by household chemicals.
Acrylic and
modacrylic fibers
Acrylic
These fibers are unique among synthetic fibers because they have an uneven surface. The fibers are formed by additional polymerization of at least 85% by weight of acrylonitrile or vinyl chanide.

Acrylic fibers can be artificial wool because it has the warmth and softness of wool but does not absorb water. It is often used ascold weather fiber for blankets and sweaters.
They have a high resistance to chemical and biological degradation as well as degradation from sunlight. Acrylic is lightweight and strong. 
High heat can melt the fabric.
Aramid and
polyimide fibers
Aramid
Polyimide fiber is spun from the polymer by wet or dry processing techniques. This is done using a polar organic solvent.
Polyimide fabric is flame retardant and can be used in high- temp applications.
These fibers are lighter and tougher than steel.

Carbon and graphite
Carbon or Graphite
These fibers are strong, light, and can be mixed with other materials. Carbon fiber technology converts carbon to graphite to form tightly packed fibers.
The material is used to produce high-quality devices such as golf-clubs and fishing rods and can be used for composites for air crafts and autos.


Elastomeric fibers
Elastomer
They are cross linked natural and synthetic rubbers, spandex fibers (segmented polyurethanes), anidex fibers (cross linked polyacrylates) and the side-by-side biconstituent fiber of nylon and spandex. The fibers can have elongations (400-800%) at break and recover fully and rapidly. 
The term elastomer is derived from elastic polymer, which is also known as rubber.  


Spandex or elastoester
spandex
Spandex is a lightweight manufactured material that can be stretched over 500% without breaking. Elastoester is a substitute for spandex.
It is used when a stretch fiber is needed.
It is a soft fabric that is resistant to abrasion and can resist body oils, perspiration and detergents. It does not have static or pilling problems.

Fluropolymer
 Fluoropolymer
It is a high-performance material that has high strength and durability. Fluoropolymers are resistant to many chemicals and high heat.
They are used in nonstick cook and bake ware.


Nylon
Polyamide
It is an artificial fiber made of polyamide which contains carbon, oxygen, nitrogen, and hydrogen.  The material is also resistant to wrinkling, does not absorb water, and it dries quickly.
Nylon can be used in carpet. High-filament nylon yarns are often blended with spandex and used in athletic apparel, swimwear, and hosiery.
The fiber is durable, strong,resists stains, hides soil, resists mildew and bacteria, prevents static,and is resistant to abrasion.
Disadvantages include: the fabric melts when exposed to high heat, can be uncomfortable to wear next to skin, and absorbs oil and grease.
Polyolefin fibers
Polyolefin fibers
They are produced by chain growth polymerization of olefins (alkenes) and contain greater than 85% polymerized ethylene, propylene, or other olefin units.
Polyolefin fibers are resistant to stains, sunlight, odor and chemicals, mildew, rot, and weather. They are fast drying and have a high wick-ability making them useful for spill cleanup.
The advantages of this material include its strength, ability to float, lightness, and resistance to abrasion.
Disadvantages include problems with static and pilling as well as a low tolerance for high temperature which tends to cause swelling in the presence aromatic and chlorinated hydrocarbons.
Polyester
Polyester
The most important synthetic fiber. They contain at least 85% of polymericester of a substituted aromatic carboxylic acid including, but not restricted to, terephthalic acid and f-hydroxybenzoic acid. The manufacturing process uses melt-spinning so the size and shape can be adjusted for specific applications.  
It is utilized in all types of clothing, home furnishings, and as a reinforcing fiber in tires, belts, and hoses. New insulating polyester fiberfill are used in high-performance outdoor wear.
It's versatile and has low raw material and production costs. Polyester is resistant to abrasion, has the ability to spring back into shape, does not absorb water, and dries quickly.
Disadvantages include, melting when exposed to high heat and it absorbs oils and grease making it difficult to clean. It does attract static electricity,
Polyethylene
polyethylene
It is produced by the formation of an ester bond between terephthalic acid and ethylene glycol.  The material floats, resists chemicals and water, and exhibits superior fiber-to-fiber abrasion.
Polyethylene fibers are used in police and military ballistic vests, helmets and armored vehicles, sailcloth, fishing lines and lifting slings, cut-resistant gloves, and a wide range of safety apparel.
High Molecular Weight Polyethylene (HMWP) is one of the world’s strongest and lightest fibers. Polyethylene fiber is pound-for-pound 10 times stronger than steel.

Polypropylene
Polypropylene
It is a vinyl polymer, similar to polyethylene. The structure has a methyl group attached to every other carbon in the backbone chain.  
Polypropylene is used for indoor-outdoor carpeting because it doesn’t absorb water.


Polyphenylene sulfide (PPS)
PPS fibers
It is a specialty fiber characterized with high resistance to thermal and chemical attack as well as resistance to heat, solvents, acids and alkalis, mildew, UV light, and abrasion.  
PPS can be used for home interior, automobile, filter bag cloth for a coal-fired boiler, electrical insulation, and as filter material for liquid and gas.  


Polyvinyl chloride (PVC)/ Vinyl
Vinyl
These fibers have a polyethylene hydrocarbon backbone with a substituted functional group to determine the physical and chemical properties of the fiber.  
PVC fibers have low success in the textile industry because of their low softening point.
They do not burn, and they resist many chemicals.

Vinyon fiber or Vinal
Vinyon is composed of 85% vinyl chloride
polymerize monomer units. Vinal fibers are at least 50% vinyl alcohol units in which at least 85% of the units are combined vinyl alcohol and acetyl cross linked units.
Application of vinyon is limited because it dissolves easily in organic solvents. Vinal resembles cotton and high strength and abrasion resistance making it useful in many applications.   
The fibers have a high chemical resistance. They are also resistant to water.
Vinyon does not burn; the fabric will melt at relatively low temperatures.
Rayon/Lyocell
 Rayon
This includes textile fibers and filaments composed of regenerated cellulose, excluding acetate. It is produced from naturally occurring polymers. The fiber is sold as artificial silk and it has a serrated round shape with a smooth surface.
Rayon is used in fashion, furnishings, sanitary products, diapers, and medical supplies.

A disadvantage is that is loses 30-50% of its strength when wet, has poor resistance to abrasion, expensive, and stretches and shrinks more than cotton.

Blended Fiber Structure

Blended fibers are manufactured from a mixture of two or more different type of fibers. Mixing fibers allows manufactures to form new textile yarns with distinct advantages. Each fiber retains its separate set of physical and aesthetic characteristics inherent in its design but the fabric acquires new characteristics depending on the type and percent of fibers used. Blends utilize the advantages of all the fibers to counteract the disadvantages of a single fiber. Synthetic fibers can be blended with natural fibers to create a material that is stronger, but more comfortable.

Coated or Sized Fabric

Coated fibers are tightly woven or knit-based fabric that is coated on one or both sides with a synthetic or natural elastomer.  The selection of fiber and fabric for coating depends on the application. Coating is used to enhance the strength, abrasion resistance, stiffness, thermal stability, water repellency and air permeability of the fabric. This technique is often seen in applications such as in life rafts and diving suits. Woven, knit, tufted, and non-woven fabrics are used in coating. There are many materials that can be used for the coating and there are several options available for applying the coating.

 

Sized fibers have been treated to reduce the hairiness around the fiber. It is part of a slashing process and reduces the hairiness that would interfere with the weaving process. This protects the yarn from yarn-to-yarn and yarn-to-loom abrasion as well as increasing the strength of the yarn so it can make it through the loom without breaking. If the process is done incorrectly, the long hair fibers around the yarn will be glued to the adjacent yarns and the strands will be damaged when they put through the loom. Proper sizing requires the size film, which can be a variety of polymers, to coat the yarn surface without excessive penetration into the body of the yarn bundle. 

Fiber Specifications

Fibers are extremely long individual strands of material. When many fibers are combined they create a fabric.
There are different requirements based on the fiber's application. Two general application categories are apparel/domestic and industrial. For industrial applications the fiber must have a tenacity of 7-8 graddenier, have 8-15% elongation at break, a modulus of elasticity of 80 graddenier or more conditioned and 50 graddenier when wet, as well as a zero strength temperature of 250°C or above. 

Fibers have their own set of specifications which should be considered in order to produce a fabric for an application. These specifications include thickness, width, length, and weight.

Thickness

Synthetic fibers can be extruded to different thicknesses called a denier. Thickness of a fiber also refers to its diameter or distance across the fiber's cross section. Synthetic fibers have a uniform diameter because it can be controlled during the manufacturing process. The opening in the spinneret is responsible for the diameter of the fiber. Very small openings produce fine filament fibers. Denier relates to the fineness of the fiber. For example a (12) - denier monofilament is used for sheer pantyhose, and a circular double-knit fiber is 140-denier.

Thickness can also be calculated by taking the square root of the ratio of ply/count.

Width

The overall width refers to the outer diameter or cut width of a roll of fabric of textile material.

Length

Fabrics and textiles are sold in roll form at varying lengths, many in excess of one mile.

Break Load (Rope/Fiber)

Breaking strength is the maximum tensile load or force that a rope, cord, webbing, or fabric will hold before breaking. Breaking strength is multiplied by a safety factor to determine the actual operating or working load of the rope or textile product. 

Fabric Specifications

Selecting synthetic fibers and synthetic fabrics requires an analysis of dimensions, properties, structural features, and applications. 

Operating Temperature

  Operating temperature is the maximum temperature at which fibers can be used continuously, without the degradation of structural or other required end-use properties. 

Fabric Strength

Fabric strength is the load per inch-width that a fabric can withstand before breaking. 

Weight

Fabric weight is the weight per unit area of woven or non-woven fabric, textile or cloth.

Thermal Characteristics

Fibers and fabrics have unique responses in the presence of heat. Heat can hurt or help the fiber or fabric, but when used correctly, heat can help fiber soften, melt, or decompose. Heat can also give fiber the ability to heat set, function properly at elevated temperatures, and function at room temperature after exposure to high temperatures.

Thermal Conductivity- Thermal conductivity is the linear heat transfer per unit area through a material for a given applied temperature gradient. Heat flux (h) = [thermal conductivity (k)] x [temperature gradient (Δ T)]

Electrical Resistivity

Resistivity is the longitudinal electrical resistance (ohm-cm) of a uniform rod of unit length and unit cross-sectional area. Resistivity is the inverse of conductivity.

Synthetic Fiber and Fabric Features

In terms of structural features, some synthetic fibers and synthetic fabrics include:
  • Chemical/fuel resistant- Materials are designed to resist damage caused by acids, alkalis, general chemicals, fuel and oils.These materials are used to seal fuel or oil tanks.
  • Electrically conductive- Textiles or fabrics include fibers with high electrical conductivity or low electrical resistivity. Often, conductive filler is added to increase conductivity. Products are used in electronic, anti-staticor electrostatic discharge (ESD) applications.
  • Electrical insulation/dielectric- Dielectricfibers, fabrics, and textiles are electrically insulating. Dielectric materials are used to form a barrier or isolator between electrical or electronic components.
  • Flame retardant fabrics- Flame retardant products reduce the spread of flames or resist ignition when exposed to high temperature, or insulate the substrate and delay damage. A UL 94 rating indicates that the material is flame retardant in accordance with Underwriters Laboratories, Inc.(UL) Flame Class 94V-0 or other equivalent ISO standards.
  • Hydrophilic/absorbent- The surfaces of hydrophilic materials absorb water. They are often used when high absorbency (many times the basis weight of the material) is important.
  • Sound proofing/insulation- Sound proofing or acoustic insulation materials are used to form a barrier or isolator between components and sources of noise or vibration.This category includes foam material products used for diffusing sound without causing a large degree of attenuation.
  • Thermal insulation/fireproofing- Thermal insulation materials provide a barrier between a component and a heat source.
  • UL approved/listed- Materials meet applicable standards from Underwriters Laboratories, Inc. (UL).
  • Hydrophobic/waterproof- Waterproof materials do not dissolve or degrade when exposed to water. The fabric may still absorb water if the product is hydrophilic and has open porosity.
  • Weather/UV resistant- Plastic or elastomer foams are resistant to ultraviolet (UV) light or sunlight. Some non-UV resistant foam will crack, yellow, or degrade on exposure to UV light.Weather resistant materials can withstand exposure to the elements, such as wind, rain, snow dust, humidity, heat, cold, and other weather conditions. 

Applications

Synthetic fibers and synthetic fabrics are used in a variety of industries and applications, including: aerospace, apparel or clothing, architecture and construction, automotive and transportation, chemical processing, electrical, electronic, filtration, marine, and medical. Specialized products can also be used to control electrostatic discharge (ESD) and provide shielding from electromagnetic interference (EMI) and radio frequency interference (RFI).

2 comments:

  1. Thank you for sharing the information.

    It is very unimaginable the world without fibers as fibers are the materials which, are used in almost every sector of the world not only to manufacture textile but, for various types of household or an industrial products like cords, firehose, nets, ropes, webbings etc.

    Fibers is made up of various chemicals and one such chemical is polyester yarn which is spun and different types of products are being manufactured. Many companies are using fibers to manufacture high and small scale industrial products and one such company is Fiberpartner ApS who is manufacturing different materials like nets, ropes, pvc coated materials etc.

    ReplyDelete