Modacrylic

Overview

A modified acrylonitrile-based fiber category, chemically distinct from ordinary acrylic.

Feel and behavior

Soft and versatile, including pile structures.

Where you find it

Faux fur, wigs, pile fabrics and protective blends.

Source and geography

Modacrylic is made from acrylonitrile, a petrochemical monomer, copolymerized with a large share of halogen-containing comonomers such as vinyl chloride or vinylidene chloride, plus minor comonomers that supply dye sites. It is used in faux fur and pile fabrics, synthetic wigs, flame-resistant workwear and underwear blends, mattress fire barriers and specialty ion-exchange fibers. Acrylonitrile itself is hazardous: it showed clear carcinogenic activity in a US National Toxicology Program mouse study, so monomer control in polymer plants matters.

Worth knowing

• Kaneka states that some Kanekalon hair fibers can be curled with hot water at about 70 to 90 C, avoiding hot tools.
• A 2016 simulated flash fire study measured about 12 micromoles per square centimeter of acid deposition under a medium modacrylic blend coverall, compared with 0.9 for FR cotton and nylon.

Types, grades and fabrics

Types and grades

Modacrylic types differ mainly in comonomer and additive content. Kaneka's Kanekalon modacrylic, introduced in 1957, is described by the producer as a copolymer of about 60 percent acrylonitrile and 40 percent vinyl chloride, used for wigs and hair products; some grades are designed so curls can be set with hot water at about 70 to 90 C. Kaneka's Protex is a modacrylic line marketed for flame-resistant fabrics. Other modacrylics are made for faux fur and pile fabrics, where fibers of different shrinkage are blended to create layered textures. Fiber fineness, cross-section and crimp vary widely between products, and heat-resistant wig fibers are separate formulations that should be identified on the label.

Fabrics and products

Modacrylic is used in wigs, hair extensions and doll hair, where it mimics human hair. It is the base of many faux fur and deep pile fabrics for coats, trims, toys and blankets. In protective clothing, it is blended with cotton or lyocell in shirts, coveralls and base layers designed to meet flame-resistance and arc-flash standards, such as ASTM F1506 for electrical workers and NFPA 2112 for flash fire protection. It also appears in mattress fire barriers and upholstery.

Buying and care

How to judge quality

For wigs, check the fiber type and whether it is labeled heat-friendly or heat-resistant; standard modacrylic can frizz or melt with styling tools. Good wig fiber should look even, soft and not overly shiny. For faux fur, look for dense, even pile, a backing that does not show through, and a label stating fiber content. For flame-resistant workwear, look for garment labels citing ASTM F1506, NFPA 2112 or NFPA 70E, with arc ratings in cal/cm2; these come from testing finished garments, not just fiber content. Beware of 'fire-resistant' claims without a stated standard.

Care in detail

For modacrylic garments and faux fur, wash in cool water on a gentle cycle or by hand with a mild detergent, and avoid hot water and hot dryers, which can shrink or mat the fibers. Air dry, shaking faux fur gently and brushing the pile once dry. Do not iron, or use only the lowest setting through a cloth. For wigs, wash in cool water with products made for synthetic hair, detangle with a wide-tooth comb from the ends upward, and dry on a wig stand. Use heat tools only on wigs labeled heat-friendly, and follow the maker's temperature limits. Launder flame-resistant workwear exactly as its label specifies; makers commonly warn against chlorine bleach and fabric softeners.

Care at a glance

Follow the complete product’s care label. Blends, dyes, finishes and construction can change suitable washing, drying and storage.

Environmental and social footprint

Modacrylic is made from acrylonitrile, a hazardous monomer, with chlorinated comonomers such as vinyl chloride, a recognized carcinogen, so monomer control in production is essential. Flame retardancy often depends on antimony compounds in addition to the halogen content. When it burns, modacrylic releases hydrogen chloride: a 2016 study in Burns, co-authored by Kaneka researchers, found higher acid deposition on skin traps with modacrylic blend coveralls than with FR-treated cotton and nylon in simulated flash fires, but concluded the levels were not enough to cause skin corrosion. Faux fur avoids animal welfare issues but sheds synthetic microfibers and does not biodegrade. Recycling options are limited because of blends and halogen content.

Tradeoffs

Origin, processing inputs, labor, product construction and useful lifetime all need specific evidence. The name alone does not establish responsible production.

A useful question to ask: What exact material, product form and documented producer stand behind this name?

Science

Data sheet

Engineered organic polymer

Polymer chemistry and fiber-forming conditions determine the starting material.

Structure and chemistry

Modacrylic chains are random copolymers in which acrylonitrile units, with polar nitrile side groups, alternate with chlorine-bearing units from vinyl chloride or vinylidene chloride. The halogen content separates it from acrylic: the US definition requires less than 85 percent but at least 35 percent acrylonitrile units. Halogens, often combined with antimony compounds, give flame resistance by interfering with gas-phase combustion. Cross-sections vary widely between trade names, from round and bean shapes to dog-bone, horseshoe and lobular forms, and forensic infrared spectra reveal the comonomer, dye-site termonomers, solvent residues and flame-retardant additives.

From source to yarn

Acrylonitrile and the halogenated comonomer are copolymerized, and the polymer is dissolved in a polar organic solvent to make the spinning dope. Filaments are formed by wet spinning into a coagulation bath or by dry spinning, then washed, drawn, crimped and cut to staple. For pile and faux fur, fibers of different fineness and shrinkage are blended so that heat treatment after knitting creates layered, fur-like surfaces. Flame-retardant additives may be incorporated in the polymer; one study added coated zinc hydroxystannate to an acrylonitrile and vinylidene chloride copolymer and reached a limiting oxygen index of 33.2 percent.

Performance in use

Modacrylic's main value is flame behavior: it shrinks away from flame and self-extinguishes rather than sustaining combustion, which is why it is blended with cotton or lyocell for flame-resistant workwear and underwear. Knitted blends of 55 percent modacrylic, 15 percent polyacrylate and 30 percent lyocell met a limited flame spread criterion with afterflame and afterglow under 2 seconds. It has low moisture uptake, so cellulosic partners add absorbency. Heat is its practical weakness: it shrinks, stiffens or glazes at relatively low ironing temperatures, an effect exploited in pile finishing but damaging in garments.

How it is identified

Burn tests are indicative only: modacrylic shrinks from the flame, burns reluctantly, self-extinguishes and leaves an irregular hard black residue with an acrid smell. Microscopically, some modacrylics cannot be told from acrylic, while others show unusual shapes. FTIR microscopy reveals the chlorinated comonomer. A solubility test helps: a forensic laboratory found that a 90:10 dimethylformamide and ethanol mixture correctly separated 59 of 60 acrylic and modacrylic samples.

History

Timeline

1. 1949Union Carbide introduced Dynel, the first modacrylic fiber. [2]
2. 1957Kaneka introduced Kanekalon modacrylic, which it describes as about 60% acrylonitrile and 40% vinyl chloride. [3]
3. 2016A full-size flash fire simulation measured acid deposition on skin traps under modacrylic blend coveralls. [4]
4. 2022California public health scientists reported modacrylic containing vinyl chloride and antimony, with fiberglass, in mattress cover fire barriers. [5]

Modacrylic developed alongside other mid-twentieth-century manufactured fibers. Its composition enabled textile roles different from conventional acrylic sweater yarn.

The deeper record

Modacrylic grew out of acrylonitrile copolymer chemistry, when copolymerizing acrylonitrile with chlorinated monomers produced fibers that would not sustain a flame. It found a durable niche in wigs and doll hair, where a forensic survey of commercial synthetic wigs identified modacrylic as the most common fiber type, and in deep-pile faux fur. More recently it has become a staple of affordable flame-resistant clothing blended with cotton or lyocell. Its use in mattress fire barriers drew scrutiny when California public health scientists found modacrylic containing vinyl chloride and antimony, alongside fiberglass, in mattress cover sock layers.

Labeling and law

Under 16 CFR 303.7, modacrylic is a manufactured fiber whose fiber-forming substance is a long-chain synthetic polymer composed of less than 85 percent but at least 35 percent by weight of acrylonitrile units. EU labels must use a fibre name from Annex I of Regulation (EU) No 1007/2011. Faux fur must be labeled by its actual fiber content, and 'flame resistant' or 'inherently flame retardant' claims should be supported by test results for the finished product. Trade names such as Protex are not generic names.

This describes what rules and standards cover. It is not legal advice; jurisdiction, product form and current rule text control.

Frequently asked

Is Kanekalon modacrylic?

Kanekalon is Kaneka's brand of synthetic hair fiber. The company describes its Kanekalon modacrylic as a copolymer of about 60 percent acrylonitrile and 40 percent vinyl chloride, introduced in 1957. Kaneka also sells other hair fibers, so check which product a wig uses.

Can you use a curling iron on a modacrylic wig?

Only if it is labeled heat-friendly or heat-resistant, and then at the maker's temperature limit. Standard modacrylic can frizz, shrink or melt under hot tools. Some Kanekalon grades are designed to set curls in hot water at about 70 to 90 C instead.

Why is modacrylic used in flame-resistant clothing?

Its halogen content makes it self-extinguishing: it shrinks from flame and stops burning when the source is removed. Blended with cotton or lyocell, it can meet standards such as ASTM F1506 and NFPA 2112 for arc flash and flash fire protection.

Is faux fur made of modacrylic?

Many faux furs are modacrylic or modacrylic blended with acrylic or polyester. Modacrylic's heat shrinkage lets makers create layered, fur-like pile. The fiber content label should state the exact mix.

Sources

• Museum of Fine Arts, Boston: Manufactured-fiber reference
• Science and Justice: Is it a modacrylic fibre? (1999)
• Journal of Forensic Sciences: A simple solubility test for the discrimination of acrylic and modacrylic fibers (2014)
• Forensic Science International: Cross-sectional shapes and FTIR profiles in synthetic wig fibers (2017)
• International Journal of Environmental Research and Public Health: Fiberglass and other flame-resistant fibers in mattress covers (2022)
• eCFR: 16 CFR 303.7, Generic names and definitions for manufactured fibers
• Kaneka: KANEKALON modacrylic (producer source)
• Mackay et al. (2016), Burns: Assessment of dermal hazard from acid burns with fire retardant garments in a full-size simulation of an engulfment flash fire
• PIP Global: FR shirts, vests and coveralls dual certified to NFPA 70E and NFPA 2112
• MFA Boston CAMEO: Modacrylic fiber
• MFA Boston CAMEO: Dynel

Cite this page

Chaos. (2026). Modacrylic. In Fibers of Earth: An independent textile atlas. https://www.hendrickresearch.com/fibers/materials/modacrylic/