You Do Need power plug adapter while traveling from Saint Barthélemy to Puerto Rico.

Here is Why You Need An Adapter

The outlet and plug type used in Puerto Rico are A and B and in Saint Barthélemy are C and E. This is how they look like.

Saint Barthélemy

In Saint Barthélemy, outlets of type C and E are in use.

Type C

Type E

Puerto Rico

In Puerto Rico, outlets of type A and B are in use.

Type A

Type B