# GATE (TF) Textile 2005 Question Paper Solution | GATE/2005/TF/67

The apparent crystallinity of a PET sample by ensity method is foudn to be 45%. The density of amorphous and crystalline PET sample is 1.355 and 1.455 g/cm3 respectively.

###### Question 67 (Textile Engineering & Fibre Science)

If the void volume of the above sample is 0.5%, the true crystallinity of the sample is

Option B
This will be calculated by crystalline region void volume.

Given-
Density of amorphous region( )=1.335 g/cm3

Density of crystalline region( )=1.455 g/cm3

Density of sample( )=1.386 g/cm3

Original Volume of crystalline region( Final volume of the crystalline region(Vc1)=Original Volume of crystalline region(Vc)-Original Volume of crystalline region x void volume %

Final volume of the crystalline region(Vc1)= Final volume of the crystalline region(Vc1)=0.6838 cm3/gm

Final density of the crystalline region( Final density of the crystalline region( Final density of the crystalline region( g/cm3

Crystallinity( Xcm)= Crystallinity( Xcm)= Crystallinity( Xcm)=0.43

Crystallinity( Xcm)%=0.43 x 100

Crystallinity( Xcm)%=43

Crystallinity( Xcm)%=45 (Ans)