Acrylic fiber acquires an eminent position in the family of synthetic fibers. Acrylic fiber is made from acrylonitrile monomer (vinyl cyanide). Its chemical name is polyacrylonitrile (PAN), has an average molecular weight of ~100,000, about 1900 monomer units. Co-monomer are vinyl acetate or methyl acrylate. Acrylic fiber contains at least 85% acrylonitrile monomer, while in modacrylic the percentage of acrylonitrile must be less than 85% but greater than 35%. Acrylic fiber is known to resemble wool as it gives the same properties as wool fiber like warmth, etc..
This polymer is formed by free radical polymerization in an aqueous suspension. The fiber is produced by dissolving the polymer in a solvent such as N, N – dimethyl-formamide (DMF) or aqueous sodium thiocyanate, passing it through a multi-hole spinneret and coagulating the resultant filaments in an aqueous solution of the same solvent or evaporating the solvent in a stream of heated inert gas. Washing, stretching, drying, and crimping complete the processing.
Acrylonitrile is the raw material that is used to make acrylic fiber. Polymerization is the first step where acrylonitrile is converted to polyacrylonitrile, and this polymerization is called addition polymerization. In next step polymer is dissolved in a solvent. However, the choice of solvent depends upon the method used for spinning. Acrylic is manufactured by either wet or dry spinning method.
In case of dry spinning, the polymer is dissolved in dimethylformamide solvent (volatile) and it forms a solution. And for wet spinning, the polymer is dissolved in dimethylacetamide solvent.
Fibers are texturized to give a light bulky wool-like hand and aesthetics. Acrylic fiber is resistant to acid and sunlight. i.e. Acrylic fibers are unique materials with several unique properties. This fiber has good resistance to acids because the polymer system does not consist of chemical group that would respond to the addition of acids This fiber has high resistance to UV degradation, and to damage from mold, mildew, and micro-organisms. The structure allows the acrylic fibers to develop wool-like bulk and resiliency.
There are four main types of acrylic fabric:
Acrylic fibers have good resistance to acids because the polymer system does not consist of any sort of chemical group that would respond to the addition of acids. Fiber is not much affected by treatment with alkalis and also not harmed by the use of organic solvents. Acrylic fiber is known for certain properties such as being lightweight, soft and insulative. Other properties such as resistance to rot, mildew, and moth make it a tough opponent in front of wool.
Because of these properties and also due to the ease with which modification can be made during synthesis, spinning, and finishing, acrylic fibres have experienced tremendous growth.
Acrylic yarn is “cheap” because it is usually priced lower than its natural-fiber counterparts and it is less soft, and warm than wool and cotton. On the other hand, it is machine-washable, hypoallergenic, and has excellent color fastness. This makes acrylic useful in certain items, like garments that need constant washing. It has good oil and chemical resistance and drying time. However, it is much more flammable than natural fibers.
Some of the major applications of fiber in commercial success:
It is widely used in winter apparel such as sweaters, imitation fur, gloves, socks, hoodies, coats, pants etc. And has replaced wool due to its low price and easy availability. It is also used as knitted yarn.
• Home Textiles:
Blankets, curtains, carpets, and rugs.
• Acrylic fabric is not much used in the industrial sector as it is highly inflammable.
The acrylic fabric has various impacts on the environment:
The acrylic fibers are non-biodegradable, and it is difficult to decompose. They can exist in the environment for about 200 years.
• Production Process:
The manufacturing of acrylic fiber involves the use of toxic chemicals and volatile substances that have the ability to harm the environment. The volatile substance can penetrate into the fields thus harming crop cultivation in terms of yield.
• Environment Pollution:
Acrylic fibres have the ability to pill on washing. The tiny balls of fibres enter the water system during washing and pollute the water and surrounding. These fiber fragments are difficult to filter.
• Health Hazards:
The polymer of acrylic is polyacrylonitrile which is flammable in nature and thus the fabric is finished with a flame retardant to avoid any sort of mishappening. However, there is a certain health risk associated with acrylic fiber that is these polymers are carcinogenic and are responsible for causing cancer and skin-related disorders.
Specialty Chemicals used in Textiles made from Acrylic Fibers
Acrylic fiber acquires an eminent position in the family of synthetic fibers. It replaces wool in major applications, particularly in hand knitting and hosiery garments. The majority of knitting yarns goes into the manufacture of pullovers, sweaters, socks, etc. Blankets and carpets are the other application where acrylic fiber competes with wool because of its high elasticity, colour brilliance, ease of washing, resistance to pilling, and good light and colour fastness. Because of these properties and also due to the ease with which modification can be made during synthesis, spinning, and finishing, acrylic fibers have experienced tremendous growth.
a) Pre-Treatment –
1. Sequestrants – POLLY 43 AS
2. Scouring Agents – POLLY IWA
3. Defoamers – POLLY 1866
1. Levelling Agents – POLLY DFT
2. Washing Agents – POLLY SN
1. Softeners – POLLY ES160