Fibre Technology I
6 ECTS
Ladok code: AT21FTThe exam is given to: ExamCode:
Date of Re-exam: 2018-04-20 Time: 09:00-13:00 Means of assistance:
Calculators.
Total amount of point on exam:: 50p Requirements for grading:
ECTS: E: 26-30 p, D: 31-35 p, C: 36-40 p, B: 41-45 p, A: 46-50 p.
Additional information:
Attempt any 5 questions out of 6.
Next exam date: Will be announced on Kronox.
The results are for the most part posted within three weeks after the exam, otherwise it’s the following date: Important! Do not forget to write the ExamCode on each paper you hand in.
Good Luck!
Examiner: Phone number:
1 Question#1
a) Write different steps involved for extraction of Flax fibers. (2) b) Write the definitions of following: (4)
1. English cotton count 2. Melt flow index (MFI) 3. Hygroscopicity
c) What do you meant by convolutions of cotton? How Mercerization process is related to this? What will be the effect on final product of fabric of mercerized cotton? (4)
Question#2
a) What the main difference is in partially oriented and fully oriented yarns? (2)
b) How the higher degree of polymerization will affect properties of melt spun fibers? (2)
c) Why do we use spin finish during the production of synthetic fibres? What happens if wrong spin finish will be selected? (2)
d) Which grade of polyethylene (PE) fibres has superior mechanical properties? What is the reason of this uniqueness? What spinning method is used to produce it? (3)
Question#3
a) Write a short description of three basic steps involved in the production of viscose rayon fibers? (3)
b) Why Zinc is used as a modifier in the production of viscose fibers? Write the chemical reaction equation. (3)
c) Given: Polyester granules having density 1013 kg/m3 at room temperature are fed through the piston spinning machine at 260 oC. The PE melt with density 975 kg/m3 at 260 °C started to come out from the spinneret. The melt throughput speed is 60 cm/50 sec and speed of second godet was fixed at 80 m/min. The PE fibers with final diameters of 35 microns were produced with SSDR=4.0. (4)
Calculate:
1. Speed of 1st godet For dtex: D=11.3 √(Tt /ρ) 2. MDR
3. Linear density in dtex For denier: D=9.44 √(Tt /ρ) 4. Linear density in denier
2 Question#4
a) What two precursors are used to produce the carbon fibers? Write the names of three
steps involved to convert these precursors to high-modulus carbon fibers. (3)
b) How the glass fibers are produced? Draw a simplified schematic diagram of the process.
(2)
c) Write the names of all sampling techniques used for testing the textile fibers. (2) d) Write two methods of counting number of twists of yarns? (3)
Question#5
a) What are the different options to manage the textile waste? Which option is least favorable? (3)
b) Write a short description of the effects of following on the properties of melt-spun fiber:
(4)
1. Mol. Wt. 2. MFI 3. SSDR 4. Die swell
c) What are the advantages and disadvantages of melt-electrospinning method? (3) Question#6
a) Which natural fiber is available in filament form? Write the basic steps involved in its production. (3)
b) Draw a schematic diagram of melt spinning process which shows the MDR and SSDR as well. (2)
c) What are the critical parameters which affect the mechanical properties of solution-wet spun fibers? (3)
