Question

Calculate the feed ratio of adipic acid and hexamethylene diamine that should be employed to obtain a polyamide of approximately 15,000 molecular weight at 99.5% conversion. What is the identity of the end groups of this product? Do the same calculation for a 19,000-molecular-weight polymer.

Answer 1

Answer:

r= 0.9949 (For 15,000)

r=0.995 (For 19,000)

Explanation:

We know that

Molecular weight of hexamethylene diamine = 116.21 g/mol

Molecular weight of adipic acid = 146.14 g/mol

Molecular weight of water = 18.016 g/mol

As we know that when  adipic acid  and hexamethylene diamine react then nylon 6, 6 comes out as the final product and release 2 molecule of water.

So

$M_{repeat}=146.14+166.21-2\times 18.106\ g/mol$

$M_{repeat}=226.32\ g/mol$

So

Mo= 226.32/2 =113.16 g/mol

$M_n=X_nM_o$

Given that

Mn= 15,000 g/mol

So

15,000 = Xn x 113.16

Xn = 132.55

Now by using Carothers equation we know that

$X_n=\dfrac{1+r}{1+r-2rp}$

$132.55=\dfrac{1+r}{1+r-2\times 0.99r}$

By calculating we get

r= 0.9949

For 19,000

19,000 = Xn x 113.16

Xn = 167.99

By calculating in same process given above we get

r=0.995