Study of Production Process of Acrylic Fiber

Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of ~100,000, about 1900 monomer units. To be called acrylic in the U.S, the polymer must contain at least 85% acrylonitrile monomer.

Acrylic Fibers: Federal Trade Commission Definition for Acrylic Fiber: A manufactured fiber in which the fiberforming substance is any long-chain synthetic polymer composed of at least 85% by weight of acrylonitrile units (-CH2-CH[CN]-)x.

Acrylic fibers

Production of acrylic fibre:

• Production: First U.S. Commercial Acrylic Fiber Production: 1950, DuPont Company.

• The polymer is formed by free-radical polymerization in aqueous suspension. The fiber is produced by dissolving the polymer in a solvent such as N,N-dimethylformamide or aqueous sodium thiocyanate, metering it through a multi-hole spinnerette and coagulating the resultant filaments in an aqueous solution of the same solvent (wet spinning) or evaporating the solvent in a stream of heated inert gas (dry spinning). Washing, stretching, drying and crimping complete the processing. 

Production Process of Acrylic Fiber:

1. The acrylic process is a "one step technology", with the following main characteristics:
2. polymerization in solution. 
3. direct feeding of the dope to spinning.
4. wet spinning.
5. DMF as solvent for both polymerization and spinning.

Production Process of Acrylic Fiber:

  

1.  Acrylic has a warm and dry hand like wool. Its density is 1.17 g/cc as compared to 1.32 g/cc of wool. It is about 30% bulkier than wool. It has about 20% greater insulating power than wool.
2.  Acrylic has a moisture regain of 1.5-2% at 65% RH and 70 deg F.
3. It has a tenacity of 5 gpd in dry state and 4-8 gpd in wet state.
4. Breaking elongation is 15% ( both states)
5.  It has a elastic recovery of 85% after 4% extension when the load is released immediatele
6. It has a good thermal stability. When exposed to temperatures above 175 deg C for prolonged periods some discolouration takes place.
7. Acrylic shrinks by about 1.5% when treated with boiling water for 30 min. 
8. It has a good resistance to mineral acids. The resistance to weak alkalies is fairly good, while hot strong alkalies rapidly attack acrylic.

Some Major Acrylic Fiber Uses:

• Apparel: Sweaters, socks, fleece wear, sportswear and childrens wear. 
• Home Furnishings: Blankets, area rugs, upholstery, outdoor furniture. 
• Other Uses: Craft yarns, sail cover cloth. 
• Industrial Uses: Asbestos replacement; concrete and stucco reinforcement.