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| Acrylic Fiber |
Acrylic Fiber
Acrylonitrile, the chemical used to create acrylic fibers and from which the general term is derived, was invented in Germany in 1893. Acrylic marketing may make use of its wool-like properties. Terms like virgin acrylic, mothproof, and moth-resistant are appealing to customers, but they don't mean anything because acrylics are naturally moth-resistant and are not recycled.
Production of Acrylic Fiber
Some acrylic fibers are dry-spun or solvent-spun, whilst others are wet-spun. Dry spinning involves dissolving polymers in a solvent, such as dimethylformamide, extruding them into heated air, and then solidifying them by evaporating the solvent. After spinning, the fibers are stretched heated to 3 to 10 times their original length, crimped, and sold as cut staple or tow. Wet spinning involves dissolving the polymer in a solvent, extruding it into a coagulating bath, drying, crimping, and collecting it as a tow for use in the high-bulk process or cutting it into staple and baling it.
Physical Structure of Acrylic Fiber
Acrylic fibers' cross-sectional form changes depending on the spinning process used to create them (Figure 1.1). A dogbone form is produced by dry spinning. Wet spinning gives some fibers a round or lima bean form. Cross-sectional form differences impact physical and visual qualities and play a role in identifying optimal end usage. Round and lima bean forms offer stronger bending stiffness, which helps to resilience, and are suitable for bulky sweaters, upholstery, and blankets. The dog-bone form imparts the softness and shines desired for various applications.
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| Figure 1.1 Acrylic cross-sectional view (a) and longitudinal view (b). |
The only acrylic fibers produced in the United States are staple fibers and tows. Staple fiber is offered in a variety of deniers and lengths to suit various spinning processes. The shrinking potential of acrylic fibers varies. Acrylics were the first to be used to make bicomponent fibers. Imported filament-yarn acrylic textiles are typically used in window coverings. There are certain microfibre acrylics available.
Chemical Composition and Molecular Arrangement of Acrylic Fiber
Acrylic fibers are made of fibers in which the fiber-forming ingredient is any long-chain synthetic polymer containing at least 85% acrylonitrile units by weight.
100% polyacrylonitrile fibers have a compact, strongly aligned interior structure that renders them essentially undyeable. They are an example of a homopolymer, which is a fiber made of only one component. A homopolymer can be shown schematically (where X refers to the ingredient that is polymerized to generate the polymer):
X XXXXXXXXXXXXXX Homopolymer
The majority of acrylics are copolymers, with up to 15% of the repeating units being anything other than acrylonitrile. This results in a more open structure and allows the dye to be absorbed into the fiber. The other repeating units provide dye sites that may be modified for certain dye classes, allowing for cross dyeing. The percentages of other repeating units and how they are arranged in respect to one another will vary. Copolymer fibers are made up of two or more compounds and can be represented as follows (where X refers to one chemical used to make the polymer and W refers to another compound used to make a more open polymer):
XXXWXXXXXXWXXXXXXWXXX Copolymer
The other repeating unit does not form a part of the main molecular chain in graft polymer acrylics. It is a side chain that is connected to the molecule's backbone chain. These molecular chains are more open, have less crystallinity, and are more dye receptive. Some fiber molecules are chemically reactive, whereas others are chemically inert. By grafting reactive groups (Z in the diagram below) onto the backbone of a chemically inert molecule (X in the diagram below), a chemically inert molecule (X in the diagram below) can be rendered reactive.
Copolymer acrylics do not have the same strength as homopolymers or graft polymer acrylics. Because acrylics are largely utilized in clothing and interiors, the diminished strength isn't a big deal.
Properties of Acrylic Fiber
Acrylic fibers are soft, light, warm, and durable. They create easy-to-clean textiles. Acrylics have been dubbed the "warmth without weight" fibers because of their low specific gravity and high bulk. Acrylics have proven effective in previously wool-dominated end applications such as sweaters and blankets. They outperform wool in terms of ease of care and are non-allergenic. Socks, fleece and faux-fur textiles, and craft yarns all use bulky acrylic yarns. Table 1.1 summarises the performance features of acrylic. |
| Table 1.1 Summary of the Performance of Acrylic in Apparel and Interior Textiles |
Aesthetics
Acrylic's visual characteristics are similar to those of wool. Acrylic is visually appealing and has a smooth, pleasant touch. Bulky spun yarns are typically textured to look like wool. Acrylic textiles, more than any other man-made material, closely resemble wool materials.
All acrylic or acrylic blend apparel and interior goods are appealing. Because of delustering, uneven cross-sectional fiber form, and fiber crimp, their luster is matte. Because these items are virtually typically made of staple fibers, they retain their wool-like look. Bulky yarns and bicomponent fibers contribute to the wool-like look and texture even more.
Durability
Acrylics have a modest level of durability. They are not as durable as nylon, polyester, or olefin fibers, but their strength is enough for clothes and interiors. The dry tenacity ranges from 2.0 to 3.0 g/d. Abrasion resistance is modest as well. At 35%, breaking elongation is moderate to high. When the fiber gets moist, it elongates. Acrylic fibers have moderate overall durability, equivalent to wool and cotton.
Acrylics and acrylic mixes used in interior textiles are long-lasting. They provide adequate abrasion resistance for upholstery materials. Depending on the product, they are tough enough to survive laundry, dry cleaning, and absorbent powder cleaning. Pilling can occur with staple fiber textiles. Low-pilling fiber variations are available, and various fabric treatments help to decrease pilling.
Acrylic is extensively used in tarpaulins and awnings because of its great weather resistance. In terms of durability, Table 1.2 compares acrylic to wool.
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| Table 1.2 Comparison of the Durability of Acrylic with Wool |
Comfort
Acrylic provides a modest level of comfort. Acrylic fibers have a less uniform and indented surface than other synthetic fibers (Figure 1.2). Acrylics are somewhat pleasant due to their uneven surfaces, despite their low absorbency (moisture regain of 1.0 to 2.5 percent). Rather than collecting moisture and becoming wet to the touch, acrylic fibers drain moisture to the fabric's outer surface, where it evaporates more quickly and cools the body.
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| Figure 1.2 Acrylic magnified 3000× shows a pitted and irregular surface. |
Another feature that contributes to the comfort of acrylics is that the fibers and yarns may be manufactured with a lot of bulk. Acrylic fibers with a latent shrinkage potential may be manufactured and will keep their bulk indefinitely at room temperature. The resultant thick materials offer moderate thermal retention, which means they keep body heat well and keep you warm in cold weather. Bulky knit sweaters are a common example.
The yarn and fabric structure can be changed to provide a warmer or cooler product. Acrylics are more comfortable than nylon and polyester in general, but they are not as pleasant as cotton in hot, humid weather or wool in cold or chilly, humid weather.
Acrylic has a specific gravity close to that of nylon. As a result, the textiles are both lightweight and long-lasting. This implies that thick acrylic sweaters are not as weighty as wool sweaters. Acrylic blankets are lighter than wool blankets of comparable weight.
Appearance Retention
Acrylic has a modest level of appearance preservation. Acrylic fibers have a moderate resilience and elastic rebound, which means they resist wrinkling throughout use and maintenance. They have a considerable degree of dimensional stability. When exposed to high temperatures acrylics shrink and steam; the fibers do not fare well in hot, humid situations.
Acrylic fibers, unlike nylon and polyester, cannot be heat-set because when heated, acrylic decomposes and discolors. However, certain acrylics may contain built-in pleats or wrinkles that are unaffected by typical wear or maintenance. The crease or pleats can be eliminated with the careful use of heat and/or steam.
Acrylic is also distinct from nylon and polyester in that garments may shrink or stretch somewhat during care. Acrylics pill because the fibers fibrillate, or break when subjected to abrasion.
If acrylic or acrylic blend items are properly cared for, the bulk properties remain permanent. Acrylic, unlike certain fabrics, is less likely to mat. Colors are permanent when some upholstery, drapery, and awning materials are solution-dyed. Solution-dyed acrylic awning textiles are popular for completing window exteriors, entryway, and outdoor entertainment spaces.
Care
Acrylic may be dry-cleaned, machine-washed, or cleaned with absorbent powder. However, due to acrylics' differ, it is extremely crucial to follow the recommendations on the care labels. The care of acrylic is compared to that of wool in Table 1.3. Because of the polymer composition, production processes, and fiber alterations, there are various fundamental acrylic fibers with somewhat different qualities.
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| Table 1.3 Comparison of Care for Acrylic and Wool |
Acrylic is resistant to most chemicals, except for strong alkalis and chlorine bleaches. This is not unexpected given that nitrogen-containing fibers are often vulnerable to alkali and chlorine degradation. Acrylic textiles, except for furlike textures, offer good wash-and-wear properties. They do not wrinkle if handled correctly and the care instructions are followed.
Some objects created from high-bulk yarns of bicomponent fibers must be machine-dried after washing to restore their form. They may be overly huge or malformed if they are blocked, dried flat, or drip-dried. Rewashing and tumble drying should return the item to its original form.
Acrylics can be dry-cleaned in some cases. However, the finish is lost from some materials, resulting in a harsh feel. As a result, care labels should be observed. Acrylics are resistant to moth damage and mildew and have good sunshine resilience.
It is especially vital for electric blankets made of acrylic to follow the prescribed care methods for acrylic or acrylic mix goods. Dry cleaning should never be used on electric blankets. Dry-cleaning chemicals damage the protective coating on the blanket's wiring, posing a danger of electric shock or fire. Interior fabrics such as drapes, upholstery, and area rugs should not be steam cleaned because acrylics can shrink.
Acrylics with antimicrobial and antifungal properties are employed in clothing, interior design, and technological applications. Nursing uniforms, shoe liners, socks, upholstery, sportswear, room-dividing drapes in hospitals and nursing homes, surgical barrier materials, and technological filters are among the products available.
Sustainability of Acrylic Fiber
Acrylic is resistant to natural degradation sources such as molds, mildew, rot, and many chemicals. Because acrylic is made from petrochemicals, there are worries about drilling in sensitive areas, oil spills, and the disposal of dangerous chemicals.
Acrylic is created from chemicals that must be processed extensively before being polymerized to form acrylic. To promote sustainability, wet- or dry-spun fibers require solvent recycling. Wet-spun acrylics must also be cleaned and dried to remove chemicals from the coagulating bath. Different varieties of acrylic are created from somewhat different basic materials; possible environmental concerns vary based on the raw ingredients and manufacturing procedures employed.
When compared to polyester, acrylic consumes around 30% more energy and significantly more water during manufacture. Acrylic is not a recyclable material. Chemical finishing is not an issue with acrylics because they may be tailored for specific end purposes. Acrylics may be colored; however, the disposal of dye leftovers is an issue.
Uses of Acrylic Fiber
Acrylic is an insignificant fabric in terms of use. Although acrylic is more commonly used in clothing, it is also employed in interior design and some technological applications. Acrylic knitted clothing products include fleece materials, sweaters, and socks. Acrylic fleece materials are occasionally utilized in active athletics. Coats, jackets, linings, and soft plush animals are made from acrylic pile fabrics and colorful furs. Antistatic acrylics are utilized in computer-clean room attire.
Craft yarns, another key application for acrylic fibers, are frequently constructed of a larger denier (5 to 6 denier). These yarns are used to knit or crochet many sweaters, vests, baby clothes, and afghans. Acrylic yarns are also utilized in crafts such as weaving, embroidery, and knitting.
Upholstery materials have a wool-like look and can be flat-woven fabrics or velvets with high stain resistance and durability. Acrylic drapery textiles are resistant to sunshine and corrosion. Acrylics are utilized in both lightweight and heavyweight blankets. Acrylic or acrylic blend rugs appear more wool-like than other synthetic fibers. Acrylic blankets and area rugs require less maintenance and cost less than wool.
Awnings and luggage, tarpaulins, boat, and other outdoor furniture, tents, vehicle coverings, carbon fiber precursors, filtration textiles, sandbags, and office room dividers are all examples of technical uses for acrylics due to their chemical and abrasion resistance and strong weathering qualities. When contacted to chemicals, fibers with high chemical resistance, such as acrylic, lose little or no physical structure or fiber characteristics. Many technological goods employ acrylic as an asbestos substitute fiber. Acrylic awnings can resist years of exposure to the sun, wind, and rain without fading, breaking, hardening, peeling, or decaying. Oasis, a cross-linked superabsorbent acrylic, is used in nonwoven filters to extract water from fuels, solvents, and other organic liquids, as well as meatpacking and gaskets and seals.
Types and Kinds of Acrylic Fiber
Acrylic is also known by the trade names BioFresh, Creslan, Wear-Dated, MicroSupreme, and Weatherbloc. Fiber variations are created that are customized to a certain end purpose. A list of possible fiber and yarn types may be found in Table 1.4.
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| Table 1.4 Types and Kinds of Acrylic Fibers and Yarns |
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