You Do Need power plug adapter while traveling from Falkland Islands 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 Falkland Islands is G. This is how they look like.

Falkland Islands

In Falkland Islands, outlets of type G are in use.

Type G

Puerto Rico

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

Type A

Type B