If your arriving plane is on time, you should have enough time to make this connection, even assuming the worst--that you will have to pick up luggage and recheck. This isn't an interline problem, but one of PVG Airport Baggage policy. Go ahead and try to interline in ORD anyway all the way to SIN, but be prepared to check that PVG luggage belt to make sure your stuff isn't on it. I think the real issue is whether the AA check-in agent will let you board in ORD, as your ticket with them ends in China. With your onward MU ticket, you are perfectly OK to Transit Without Visa per the Chinese--but if you get a clueless ORD AA check-in agent, you might encounter a bit of a battle to convince them.