Five grams of 1.5 denier polyester fibre of density 1.39 g/cm3 is packed in a cylinder of 30 mm diameter with perforated ends to make a fibre plug of 20 mm length.
Question 71 (Textile Engineering & Fibre Science)
Percentage porosity of the plug would be approximately
(A) | 25 |
(B) | 50 |
(C) | 75 |
(D) | 100 |
[Show Answer]
Option C is correct.
Given in the question-
Fineness of polyester fibre=1.5 denier
Fibre density()=1.39 g/cm3
Total weight of fibre(m)=5gm
Packed in a cylinde,diameter(D)=30 mm
To make fibre plug,length(l)=20 mm
% Porosity of plug=?
As we know,
Mass=volume x density
Total weight of fibre=Volume of cylinder x density of cylinder
M=V X dy
5=Area of cylider x length of plug x dy
dy=353.86 x 1000 g/m3
dy=353.86 x 1000/1000000 g/cm3
dy=0.354 g/cm3
By formula-
Porosity%=1-Packing coefficient
Packing coefficient=Density of cylinder(yarn)/density of fibre
Packing coefficient=dy/df
Packing coefficient=0.354/1.39
Packing coefficient=0.255
Now,
Porosity=1-0.255
Porosity=0.745
Percentage Porosity=74.5
=75 (Ans)