Question 45 (Textile Engineering & Fibre Science)
Consider the following assertion [a] and reason [r] and choose the most appropriate answer
[a] Controlled reduction treatments are commercially used for shrink resist finishing of wool
[r] Reduction disrupts the disulphide bonds, which are responsible for wool shrinkage
|(A)||[a] is right [r] is wrong|
|(B)||[a] is right [r] is right|
|(C)||[a] is wrong [r] is wrong|
|(D)||[a] is wrong [r] is right|
Answer / Solution
Frequently Asked Questions | FAQs
What is shrink resistant finish?
Shrink resist finishing is a textile treatment applied to wool fibers or woolen fabrics to minimize or prevent shrinkage during washing or other wet processes. Wool is a natural fiber that has a tendency to shrink when subjected to moisture, heat, or agitation, which can lead to changes in its dimensions and properties. Shrink resist finishing techniques are used to mitigate this natural characteristic of wool and ensure that woolen fabrics maintain their desired shape and size after washing or other wet treatments.
There are several methods used for shrink resist finishing of wool, including:
Resin Treatment: Wool fibers or fabrics can be treated with a resin finish, such as a melamine-formaldehyde or dimethyloldihydroxyethyleneurea (DMDHEU) resin, which forms cross-links with the wool fibers, making them less prone to shrinkage. The resin finish is typically applied by padding, exhaust, or spray methods, and then cured at high temperatures to set the resin.
Chlorine Treatment: Wool can be treated with chlorine-based chemicals, such as sodium hypochlorite or chlorine gas, which modifies the structure of the wool fibers and reduces their ability to shrink. Chlorine treatment is typically carried out in an aqueous solution, and the concentration, temperature, and duration of treatment are carefully controlled to achieve the desired level of shrink resist properties.
Polymer Coating: Wool fibers or fabrics can be coated with a thin layer of a polymer, such as polyethylene, polyurethane, or acrylic, which provides a barrier against moisture and minimizes shrinkage. The polymer coating is typically applied by methods such as coating, spraying, or foaming, and then cured or dried to set the polymer.
Enzyme Treatment: Enzymes, such as protease or amylase, can be used to treat wool fibers or fabrics, which can modify the structure of the fibers and reduce their shrinkage tendency. Enzyme treatment is typically carried out in an aqueous solution at controlled pH and temperature, and the duration of treatment is carefully controlled to achieve the desired level of shrink resist properties.
Heat Treatment: Wool fibers or fabrics can be subjected to controlled heat treatment, such as steam or dry heat, which can relax the fibers and minimize their shrinkage during subsequent wet processes. Heat treatment is typically carried out in specialized equipment that allows for precise control of temperature and duration.
Shrink resist finishing of wool is an important process in the textile industry to ensure that woolen fabrics maintain their shape and size after washing or other wet treatments. The specific method used for shrink resist finishing depends on the desired level of shrink resist properties, the type of wool or woolen fabric being treated, and the requirements of the end-use application.