Anna University B Tech-Fifth Semester
Physical Structure and Properties of Fibres
Time: 3 Hours
Max. Marks: 100
Answer all the Questions
Part A (10 x 2 = 20 marks)
1.Give the chemical structure of cotton fibres.
2.Mention the advantages of using infra red radiation against X ray diffraction method.
3.What is the effect of moisture on fibre density.
4.Define the terms “heat of sorption” and “heat of wetting”.
5.Why cotton gains strength when wetted against viscose rayon.
6.Tenacity of viscose rayon is ______N/Tex.
7.Explain the term elastic recovery.
8.How do you measure the lusture of fibre.
9.Discuss the role of friction in yarn manufacturing.
10.The melting point of polyester is_______deg C.
Part B (5 x 16 = 80 marks)
11. Explain the term thermal conductivity. Give the relevant values of thermal conductivity for cotton, wool, silk, poly propylene.
i) Describe briefly the morphological structure of cotton fibre.
ii)Give the chemical structure of wool and nylon 6.
12.B Give an account of the methods of determining the fibre structure.
13.A Describe the containing powers and the factors influencing the rate of conditioning.
i) What are sorption isotherms. Give the moisture regain values of cotton, wool, polyester and nylon 6.
ii)Discuss briefly the methods of determining the heat of wetting.
14.A. Describe the methods of measuring birefringence of fibres and their merits and demerits. Give the relationship between birefringence and tenacity of fibres.
14.B Give the role of friction in fibre processing. Describe the methods of measuring friction of single fibres.
15.A .What is dielectric constant of a medium. Describe a method to measure electrical resistance of a fibre. What is the effect of relative humidity on the electrical resistance of fibres.
15.B Mention the structural changes that occur in the fibres following heat setting process.