What is Acrylic Fibre?
Acrylic is a synthetic polymer fibre made from a combination of chemicals, primarily acrylonitrile and a few other monomers. Acrylic fibres are known for their softness, lightweight, durability, and ability to retain their shape and color after washing. It has great affinity with acid dyes. Acrylic fibres are spun from polymers that are made from monomers containing a minimum of 85% by mass acrylonitrile in the chain.
Youngest among the major synthetic fibres is polyacrylonitrile. Acrylic is a generic name given to fibres which have a chemical base of acrylonitrile (at least 85%) plus a minor constituent which has been copolymerized to increase the dye affinity of the fibre. It is the minor component of the fibre which gives individuality to the fibre.
Acrylic fibres are commonly used in the textile industry for a variety of applications such as apparel, upholstery, and carpets. Acrylic fibers can be blended with other fibres like wool or cotton to enhance their properties.
Acrylic fibers are also known for their resistance to fading, mildew, and insects, making them an excellent choice for outdoor fabrics. Additionally, acrylic fiber can be easily dyed, allowing for a wide range of colors and shades.
Properties of Acrylic Fibre:
Physical properties of acrylic fibre:
Physical properties of acrylic fibre is given in below table.
|Tensile Strength||0.7-1.6 GPa|
|Elastic Modulus||2.6-3.6 GPa|
|Elongation at Break||10-50%|
|Flammability||Melts and drips, may self-extinguish|
|Abrasion Resistance||Moderate to good|
|Chemical Resistance||Resistant to acids and alkalis|
Chemical properties of acrylic fibre:
Acrylic fibre has the following chemical properties:
- Chemical resistance: Acrylic fibres are resistant to most acids and alkaline solutions. They are also resistant to bleaches and oxidizing agents.
- Hydrophobicity: Hydrophobic in nature, which means they do not absorb moisture readily. They can, however, hold onto moisture that is present in the atmosphere.
- Thermal stability: Have good thermal stability and can withstand temperatures up to 160-250°C without melting.
- Resistance to sunlight: Have good resistance to sunlight, and they do not degrade or fade easily when exposed to UV radiation.
- Solubility: Acrylic fibres are insoluble in water and most organic solvents.
- Flammability: Flammable and can melt and drip when exposed to heat. They may self-extinguish when the heat source is removed.
- Resistance to microorganisms: They are resistant to mildew and other microorganisms.
- Chemical modification: Acrylic fibres can be chemically modified to enhance certain properties or to produce different types of fibres.
Mechanical properties of acrylic fibre:
Acrylic fibres have the following mechanical properties:
- Tensile strength: Have good tensile strength, ranging from 0.7 to 1.6 GPa, which is similar to wool fibres.
- Elasticity: Highly elastic, with an elastic modulus of 2.6-3.6 GPa. They can stretch up to 10-50% of their original length before breaking.
- Abrasion resistance: Moderate to good abrasion resistance and can withstand wear and tear.
- Flexural strength: Good flexural strength, which means they can withstand bending and twisting without breaking.
- Fatigue resistance: Acrylic fibres have good fatigue resistance, which means they can withstand repeated loading without breaking.
- Impact resistance: These fibres have good impact resistance, which means they can withstand sudden impacts without breaking.
- Creep resistance: Have low creep resistance, which means they may deform over time when subjected to constant load or stress.
Manufacturing Process of Acrylic Fibre:
Acrylic fibre manufacturing is a complex process that involves several steps to create fibres with the desired properties and characteristics. Production flow chart of acrylic fibre is given below.
Flow chart of acrylic fibre manufacturing
Briefly describe above steps of acrylic fibre production:
1. Polymerization: The first step in acrylic fibre manufacturing is polymerization, which is the process of combining two or more chemicals to create the acrylic polymer. This process typically involves heating the reactants in a reaction vessel, under specific conditions of temperature, pressure, and time. The resulting polymer is a viscous liquid that can be further processed to create fibres.
2. Filtration: Once the polymerization is complete, the mixture is filtered to remove any impurities or unreacted chemicals. This step is critical to ensure the purity and quality of the final product, as any impurities or contaminants can affect the performance and properties of the acrylic fibres.
3. Spinning: After filtration, the polymer is spun into fibres using a process called spinning. The polymer is melted and extruded through a spinneret, which is a metal plate with many small holes. The molten polymer is forced through the holes, creating long, thin strands of acrylic fibre.
4. Drawing/Heat: The spun fibres are then stretched or drawn, which aligns the polymer chains and increases the strength and durability of the fibres. Drawing can be done either by mechanical means, such as using rollers or pulling devices, or by heating the fibres to a specific temperature and then stretching them. The heat also sets the fibres, locking in the molecular structure.
5. Crimping: The drawn fibres are then crimped to create a more natural, fluffy texture. Crimping is done by adding a twist to the fibres, which creates a series of waves or curls. This step gives the acrylic fibres a more voluminous and comfortable feel, making them ideal for use in clothing and other textiles.
6. Cutting: Finally, the crimped fibres are cut to the desired length, typically ranging from a few millimeters to several centimeters. The length of the fibres determines their end use, with longer fibres used for heavier textiles and shorter fibres used for lighter fabrics.
Application / Uses of Acrylic Fibre:
Acrylic fibre is a versatile synthetic material that has a wide range of uses across various industries. Here are some common uses of acrylic fibre:
a) Clothing and textiles: Acrylic fiber is used with wool to manufacture sweaters. Besides, acrylic fibres are used for making knitwears, sportswear, blankets, flocked velvets and simulated fur fabrics, dress materials and suitings, wigs, childreen’s wear, underwear, swim-suits, pullovers, draperies etc.
b) Home furnishings: They are used in the production of a variety of home furnishing products like carpets, rugs, and upholstery. They are resistant to stains, fading, and wear and tear, making them ideal for high-traffic areas like living rooms, hallways, and bedrooms.
c) Industrial textiles: These fibres are used in a range of industrial applications due to their resistance to moisture, chemicals, and UV radiation. They are used in products like awnings, sails, and outdoor gear like tents, backpacks, and sleeping bags.
d) Medical textiles: Acrylic fibres are used in the production of medical textiles like wound dressings, surgical gowns, and masks due to their hypoallergenic properties, softness, and resistance to bacteria and mold.
e) Craft materials: They are also commonly used in crafting and DIY projects like knitting, crocheting, and weaving due to their affordability, versatility, and availability in a range of colors and textures.
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