There certainly are plastic companies in Santo Domingo, as you mentioned HB, like Plastifab, for instance.
I used to do business with them when I had the juice bar, for containers, but we need to know what the OP is looking for, as the term "polyurethane" could mean different things to different people.
BTW: On another nore... Did you know that polyurethane is considered to be the most versatile of all the plastics?
PS: Can you tell that I used to work in industrial plastics?
A fascinating business, I might add.