Question

PROBLEMS 1. Explain why the ratio of the density of the crystalline regions, Pa, to the density of the amorphous regions, P, is larger for nylon-6,6 than for isotactic polystyrene. L! nit roll in which the

Answer 1

There are two main points for crystalline regions in a polymer

1. straight chain and regular spaced side groups facilitate more crystalline region
2. crystalline regions are more densely packed compared to amorphous region

From the above facts it is clear that being a straight chain polymer nylon 6,6 having higher ρ_c than ρ_a. Same is happened with isotactic polystyrene as this is also a straight chain polymer. But when we compare the ratios of ρ_C to ρa for both case it is higher for nylon 6,6 because it is having smaller side groups and hence it can arrange themselves more compactly giving higher value of ρ_c. but in case of isotactic styrene which is having bigger side group (benzene ring) on same side cannot arrange them more compactly hence giving less ρ_C value compared to nylon 6,6.

for more information

isotactic: side groups on same side

atactic : no regular manner for side groups

syndiotactic: alternate arrangement of side groups

$//img.homeworklib.com/questions/c4118780-6fbe-11ea-a51d-79635e6ccfeb.gif?x-oss-process=image/resize,w_560$

Here compared to isotactic and atactic syndiotactic will give more ρ_C value as this can pack more densely