Question

What method is commonly used for the estimation of the percentage of Spin finish?

• A. Kjeldhal
• B. Methyl Alcohol
• C. Isopropyl Alcohol
• D. Ethyl Alcohol

Hint:

Remember the following laboratory methods: \[ \begin{array}{|c|c|} \hline \textbf{Test} & \textbf{Common Method/Agent} \hline Spin Finish Estimation & \text{Isopropyl Alcohol (IPA)} \hline Protein/Nitrogen Analysis & \text{Kjeldahl Method} \hline \end{array} \] For textile engineering examinations, remember the simple association: \[ \boxed{ \text{Spin Finish} \Longrightarrow \text{Isopropyl Alcohol (IPA)} } \]

Answer 1

The Correct Option is C

Concept: Spin finish is a thin layer of lubricant and antistatic chemicals applied to synthetic fibres during manufacturing. It reduces fibre-to-fibre and fibre-to-metal friction, minimizes static electricity, and improves the running performance of fibres during spinning, drawing, and weaving. The amount of spin finish present on a fibre is expressed as a percentage of the fibre weight. To determine the spin finish content, the finish is extracted from the fibre using a suitable solvent, and the percentage is calculated from the loss in weight. Among the various solvents available, Isopropyl Alcohol (IPA) is the most commonly used because it effectively dissolves spin finish without damaging the fibre.

Step 1: Understand the purpose of spin finish.
Spin finish is applied to synthetic staple fibres in order to \[ \begin{aligned} &\bullet\ \text{Reduce friction between fibres,} &\bullet\ \text{Reduce static electricity,} &\bullet\ \text{Improve fibre cohesion,} &\bullet\ \text{Facilitate smooth spinning and processing.} \end{aligned} \] Since excessive or insufficient finish affects yarn quality, its percentage must be estimated accurately.

Step 2: Identify the commonly used estimation method.
The estimation of spin finish is generally carried out by solvent extraction. Among the commonly used solvents, \[ \boxed{\text{Isopropyl Alcohol (IPA)}} \] is preferred because
• It efficiently dissolves spin finish oils.
• It evaporates easily after extraction.
• It does not significantly affect the fibre structure.
• It provides reliable and reproducible results. Hence, the estimation of spin finish percentage is commonly carried out using Isopropyl Alcohol.

Step 3: Examine each option.
Option (A): Kjeldhal The Kjeldahl method is used for the estimation of nitrogen or protein content and is not applicable for determining spin finish. \[ \boxed{\text{Incorrect}} \] Option (B): Methyl Alcohol Although methanol is an industrial solvent, it is not the standard solvent used for spin finish estimation. \[ \boxed{\text{Incorrect}} \] Option (C): Isopropyl Alcohol Isopropyl Alcohol is the standard solvent used for extracting and estimating spin finish from synthetic fibres. \[ \boxed{\text{Correct}} \] Option (D): Ethyl Alcohol Ethyl alcohol is not commonly employed for routine spin finish estimation. \[ \boxed{\text{Incorrect}} \]

Step 4: Write the final answer.
Thus, the commonly used method for estimating the percentage of spin finish employs \[ \boxed{\text{Isopropyl Alcohol (IPA).}} \] Therefore, \[ \boxed{\text{Option (C) is the correct answer.}} \]