Modacrylic fibre is a modified acrylic fibre.

Modacrylic fibre is a man-made (manufactured) fibre in which the fibre forming substance is any long chain synthetic polymer composed of less than 85% but at least 35% by weight of acrylonitrile monomer units. (-CH2CH[CN]-)x. Modacrylic fibres are made from resins that are copolymers (combinations) of acrylonitrile and other materials, such as vinyl chloride, vinylidene chloride or vinyl bromide. These substances are added to the fibre to give it better flame-retardant properties. Modacrylic fibres are either dry spun or wet spun.

The first modacrylic (modified acrylic) fibre, Dynel® was introduced in 1949; many later followed but the only one still in production at the end of the twentieth century is SEF [Solutia]. The resilient modacrylic fibres have an irregular cross section and fair elastic recovery (79-99% at 2% elongation). SEF has a low moisture regain of 2.5%. It will maintain its properties to temperatures of 190C (375F). Modacrylic fibres are resistant to sunlight, bleaches and are considered non-allergenic.

These fibres are produced in both staple and tow forms. They can also be made in various lengths, crimp levels and deniers. The shrinkage of Modacrylic can also be controlled so that good imitations of ‘Fake Fur’ can be made where all of the fibres are slightly different lengths.

A modacrylic is a synthetic copolymer. Most of its properties are similar to acrylics. Modacrylic fibre is inherently flame resistant. Although it burns when directly exposed to flame, it doesn’t melt or drip and is self-extinguishing when the flame is removed. Modacrylic is widely used in high performance protective clothing, such as firefighting turnout gear, because flame resistance is combined with other desirable textile properties such as durability and good hand feel. Garments of modacrylic fabric have good resistance to wrinkling when worn; can be permanently pleated and creased by heat-setting; and are often machine washable, requiring moderate temperature and special care to avoid setting wrinkles.

Because modacrylic fibres are fire resistant and self-extinguishing, they are commonly used in children’s sleepwear. Modacrylics are soft, strong, resilient, and dimensionally stable. They can be easily dyed, show good press and shape retention, and are quick to dry. They have outstanding resistance to chemicals and solvents, are not attacked by moths or mildew, and are nonallergenic. Among their uses are in apparel linings, furlike outerwear, paint-roller covers, scatter rugs, carpets, and work clothing and as hair in wigs.

Modacrylic fibre’s durability is comparable to wool, that is, its abrasion resistance and tenacity is rather low. Modacrylic fibre is chemical resistant. It retains its strength in concentrated acid/alkaline environments, which is useful for certain types of industrial filtration. Modacrylic is also on the extreme negative end of the triboelectric scale, and when combined with another more positive fibre such as polypropylene, results in a triboelectric media with improved filtration efficiency. If modacrylics are ironed, temperature settings must be low and steam should be avoided.

The major manufacturer and suppliers of modacrylic fibres are Kaneka and Aramid HPM.

Characteristics of Modacrylic Fibre



Easy to dye to bright shades

Abrasion resistant

Flame resistant

Quick drying

Resistant to acids and alkalies

Shape retentive

The low softening temperatures of modacrylic fibres allow them to be stretched, embossed and moulded into special shapes. The fibres may be produced with controlled heat shrinkage capacities. When fibres of different shrinkages are mixed in the surface of a pile fabric, the application of heat develops fibres of different lengths, producing a surface that resembles natural fur.

Properties of Modacrylic Fibre


General Properties
Chemistry35% acrylonitrile / 65% vinylidene chloride
Size3 denier x 51mm cut length
Crimp Level3.8 crimps/cm
Moisture3.5% (typical)
Tensile Strength (Tenacity)Fair – Good
Abrasion ResistanceFair – Good
Static ResistanceFair – Poor
Heat ResistanceFair
Wrinkle ResistanceGood
Resistance to SunlightExcellent
Flame ResistanceDoes Not Burn

Thermal Properties

LOI28 to 32

Mechanical Properties

Strength2.6 cN/den (dry)
Elongation28% (dry)


Application of Modacrylic Fibre

 Modacrylic fibres are used, alone or in blends, in fabrics for various application as follows:
Apparel: Dresses, suits, sportswear, deep-pile coats, trims and linings, simulated fur, wigs and hair pieces, children’s sleepwear, career apparel.

Fabric: Fleece, knit-pile fabric backings, nonwovens

Home Furnishings: Awnings, blankets, carpets, flame-resistant draperies and curtains, scatter rugs

Other Uses: Filters, industrial fabrics, paint rollers, stuffed toys, and chemical-resistant clothing.

 Precaution for Modacrylic Fibre
Dry-cleaning or fur-cleaning process is suggested for deep-pile garments. For washable items:

Machine wash in warm water and add fabric softener during the final rinse cycle.

If dryer is used, use low setting and remove articles as soon as tumbling cycle has stopped.

If ironing is required, use low setting. Never use a hot iron. (For specific instructions, refer to garment’s sewn-in care label.)




Article by Ms. Hetal Mistry

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