GATE (TF) Textile 2005 Question Paper Solution | GATE/2005/TF/66

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

Question 66 (Textile Engineering & Fibre Science)

The density of the sample in g/cm3 will be

[Show Answer]

Option C

Density of amorphous region(\rho_a)=1.335 g/cm3

Density of crystalline region(\rho_c)=1.455 g/cm3

Density of sample(\rho_f)=?

By formula-

Crystallinity( Xcm)=\frac{\rho_c}{\rho_f}\times\frac{\rho_f-\rho_a}{\rho_c-\rho_a}



0.45 \times  0.12 \times \rho_f=1.455 \times (\rho_f-1.335)

0.054 \times \rho_f =1.455 \times \rho_f-1.942

1.942=1.455 \times \rho_f-0.054 \times \rho_f

1.942=1.401 \times \rho_f


\rho_f=1.386 (Ans)

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