Last Updated: June 30, 2026
What Is Modacrylic Fiber?
Modacrylic fiber is a synthetic fiber made from modified acrylonitrile polymers containing between 35% and 85% acrylonitrile by weight. It belongs to the acrylic fiber family but is classified separately because of its unique composition and inherent flame-resistant properties. When a fabric needs flame resistance, softness, and warmth at the same time, modacrylic often enters the conversation. It has been used in protective apparel, interior textiles, fake fur, wigs, blankets, and other specialty products. The fiber was first manufactured commercially in 1949, and its place in the fiber family was separated from acrylic in 1960. Even now, the generic name acrylic is sometimes used in the global industry to refer to modacrylic as well.
Background and Classification
Modacrylic fibers were first manufactured commercially by Union Carbide Company in 1949 before the production of acrylics. Because the composition of modacrylics is similar to that of acrylics, both fibers were at first included in the acrylic classification, but in 1960 the FTC ruled that a separate generic category should be established for modacrylics. Increasingly, though, the generic name acrylic is used in the global industry to refer to modacrylic as well.
According to the Federal Trade Commission, modacrylic fibers are manufactured fibers in which the fiber-forming substance is any long-chain synthetic polymer composed of less than 85 percent but at least 35 percent by weight acrylonitrile units, except when the polymer qualifies as rubber.
Modacrylic is a synthetic polymer of modified acrylonitrile. It is known for its fire resistance, soft hand, and warmth.
Modacrylics are the economically most important modification of PAN. According to DIN 60.001, they consist of at least 50 percent and less than 85 percent by mass of polyacrylonitrile. Halogen contents of 25 to 35 percent are common.
Manufacture of Modacrylic fiber
Modacrylic fibers are made from copolymers of acrylonitrile with other compounds, such as vinyl chloride, vinylidene chloride, or vinyl bromide. The manufacturing process for modacrylic is similar to that for acrylic. The polymer formed in the polymerization reactor is dissolved in an appropriate solvent, dry or wet spun, then drawn and cut into staple lengths. Varying degrees of crimp may be added to the fiber depending on its projected end uses.
Some modacrylics are made by polymerizing the components, dissolving the copolymer in acetone, pumping the solution into a column of warm air, and stretching while hot. The solvent, acetone, is easy to reclaim and recycle.
Properties of Modacrylics
Physical Properties
The cross section of modacrylic fibers is dog-bone or slightly irregular in shape. The longitudinal appearance usually shows some striations, or it may have a grainy effect. The specific gravity of modacrylics is 1.3, which is comparable to wool, so the fibers feel light but also have good insulating qualities.
Modacrylics have an attractive appearance similar to that of acrylic. Luster varies from a soft, matte luster that resembles wool to a brighter luster that resembles the shiny guard hairs of fur. Modacrylics are poor conductors of heat.
Mechanical Properties
Modacrylics are similar to acrylic fibers in their mechanical properties. Strength is low, similar to that of wool; modulus and elongation are slightly higher than acrylics. Modacrylics have good recovery from stretching and bending. Abrasion resistance is similar to acrylic, and elastic recovery is superior to that of acrylic.
Modacrylics are soft, warm, and resilient with a tendency to pill. They pill more quickly, are more sensitive to heat, mat more readily, and are not as resilient as acrylics. They exhibit moderate resiliency and good dimensional stability.
Chemical Properties
The absorbency of the fibers is low, and the moisture regain is between 1.5 and 3.5 percent. With this regain, the stain resistance to waterborne soil is fairly good.
A significant advantage of modacrylic, which determines many product end uses of the fiber, is its flame resistance. Modacrylic fabrics will burn when placed in a direct flame but will self-extinguish as soon as the flame is removed. The other monomers in the acrylonitrile polymer contain chlorine or bromine, which retard burning. Inclusion of amounts of these monomers greater than 15 percent in the polymer is necessary to confer flame resistance to the fiber, hence the distinction drawn between modacrylic and acrylic fibers.
Modacrylics were the first inherently fire-resistant synthetic fibers; they do not support combustion, are very difficult to ignite, are self-extinguishing, and do not drip. The LOI value of modacrylic fibers is 26 to 31, which is significantly higher than that of PAN. However, toxic chlorinated hydrocarbons are released in the event of fire.
The melting point of modacrylics is low, about 370°F to 410°F. They are more heat sensitive than acrylics. If modacrylic fabrics are ironed, very low temperature settings must be used. If a dryer is used, temperatures should be set for low or no heat.
Chemical resistance of modacrylics is good. Dry-cleaning solvents will not affect them adversely. Some modacrylics may be discolored by strong bases, but their resistance to acids is good to excellent. Modacrylics are resistant to acids, weak alkalis, most organic solvents, mildew, and moths. They have very good resistance to sunlight and flame.
Environmental Properties
The resistance to deterioration from light is fairly good. Neither moths nor mildew attack modacrylics. Age has no apparent effect.
Modacrylic is resistant to natural degradation. The concerns expressed for acrylic generally apply to modacrylic. Modacrylic is more sustainable compared to acrylic. Modacrylic is produced only using dry spinning and the solvent, acetone, is easy to reclaim and recycle. Modacrylic is used in small quantities.
Other Properties
Modacrylics have good dimensional stability. However, their sensitivity to heat may result in some shrinkage if they are dried in a dryer at high temperatures. The resistance to abrasion of modacrylic fibers is moderate.
Uses of Modacrylic Fiber
The use of modacrylic in interior design is limited. Polyester has become the fiber of choice in most former modacrylic applications. Modacrylic is still used as a blend percentage in upholstery and drapery textiles.
The major areas of use for modacrylic fibers include pile and fleece fabrics for apparel and blankets. Flame-resistant draperies and curtains, paint roller covers, and filters are also made from modacrylics. In past years modacrylic was used extensively as the outer fur-like fabric for stuffed toys, as well as in such specialty uses as airline blankets. Despite the advantages of flame resistance and washability, however, its use is declining in favor of polyester that has been treated with a flame retardant.
Because these fibers have a low softening temperature and a high thermal shrinkage potential, a variety of texturizing treatments can be applied to simulate the textures and characteristics of fur fibers. Many fake fur fabrics are made from modacrylic fibers. The combination of good resilience with abrasion resistance makes modacrylic fibers especially suitable for use in high-pile fabrics, where they can simulate luxurious furs. They are also used in some industrial fabrics that take advantage of their flame resistance and good chemical resistance.
Modacrylic fibers are used in applications where environmental resistance is needed or where flame retardancy is necessary or required by law or building codes. End uses include outdoor fabrics, awnings, and marine applications; protective apparel, such as shirts and trousers for electric line personnel; interior textiles, such as upholstery, window-treatment fabrics, and blankets; and technical applications such as filters, paint rollers, and stuffed toys. Because of its heat sensitivity, modacrylic is used to produce realistic fake furs and wigs or hairpieces that can be curled with a curling iron. Many modacrylics are mass-pigmented rather than dyed.
Trademarks and Special Products
The Kaneka Corporation of Japan makes a modacrylic fiber called Kanecaron, which is used in fake fur products, and Kanekalon, for wigs and stuffed toys. S.E.F.® (self-extinguishing flame) is one trade name.
Modacrylic fibre, Teklan, is a copolymer made with equal weight proportions of vinylidene chloride and acrylonitrile and some small but critical quantities of other ingredients. The fabric made from this is flame proof, passing standards like British Standard 3120. Some special properties of this fibre and fabric include flame proof, good abrasion resistance, resistance to photodegradation, resistance to microbial attack, and low shrinkage in boiling water. It is used for making T-shirts and children’s clothing.
MAC fibers are used, among other things, for protective clothing, children’s and nightwear, and as imitation fur, pure and in blends. Wig hair can also be made from MAC. Modacrylics are particularly suitable for home textiles in public buildings due to their flame retardant properties.
Care Procedures
Deep-pile garments must be cleaned professionally to avoid crushing or altering the appearance of the pile. Other modacrylic fabrics are machine washable, but special care should be taken to avoid exposing them to very high temperatures because of their heat sensitivity. Stuffed toys with modacrylic exteriors can usually be washed and air dried. Low dryer temperatures must be used, and ironing should be done with only a warm, not hot, iron. Some modacrylic fibers are discolored by the use of chlorine bleaches.
Modacrylics can be washed or dry cleaned with special care. The heat-sensitive fibers shrink at 250°F and stiffen at temperatures over 300°F. For machine-washing, use warm water and tumble dry at a low setting. The lowest iron setting should be used. Some furlike fabrics are dry cleanable; some require special care in dry cleaning, no steam, no tumble or tumble only on cold; and some should be cleaned by a furrier method.
Modacrylics are more sensitive to loss of appearance from improper care than the acrylics. The precautions regarding steam cleaning discussed with acrylics also apply to modacrylics.
Conclusion
Modacrylic fibers stand out mainly because of their flame resistance, soft hand, and warmth. Their low absorbency, fair chemical resistance, and light weight make them useful in protective apparel, interiors, and imitation fur. At the same time, heat sensitivity and careful laundering remain the main limits. Even with changing market preferences, modacrylic will likely continue to hold a place in niche textiles where self-extinguishing performance is needed.
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor to Wikipedia.
