Nylon-6,6 is made from two monomers each of which contain 6 carbon atoms - hence its name.
One of the monomers is a 6 carbon acid with a -COOH group at each end - hexanedioic acid.The other monomer is a 6 carbon chain with an amino group, -NH2, at each end. This is 1,6-diaminohexane (also known as hexane-1,6-diamine).
Simple amides are easily hydrolysed by reaction with dilute acids or alkalis. Hydrolysis is faster at higher temperatures. Hydrolysis by water alone is so slow as to be completely unimportant. Kevlar is rather more resistant to hydrolysis than nylon is.
If you spill something like dilute sulphuric acid on a fabric made from nylon, the amide linkages are broken. The long chains break and you can eventually end up with the original monomers - hexanedioic acid and 1,6-diaminohexane.
Because you produce small molecules rather than the original polymer, the fibres are destroyed, and you end up with a hole!
