Isn’t it exactly like nylon 6 vs nylon 66?
It’s hard to draw it out in the comment here but the repeating unit of Kevlar is: [C=O-NH-Ph-NH-C=O-Ph-]
and poly-PABA would be [C=O-Ph-NH-C=O-Ph-NH-]
where I’m using Ph as an abbreviation for a phenyl group.
maybe this will help: https://www.google.com/search?site=&source=hp&q=nylon+6+crystal+structure&udm=2
Isn’t it exactly like nylon 6 vs nylon 66?
It’s hard to draw it out in the comment here but the repeating unit of Kevlar is: [C=O-NH-Ph-NH-C=O-Ph-]
and poly-PABA would be [C=O-Ph-NH-C=O-Ph-NH-]
where I’m using Ph as an abbreviation for a phenyl group.
maybe this will help: https://www.google.com/search?site=&source=hp&q=nylon+6+crystal+structure&udm=2