Exhibit 99.1

                            Explanation of Responses


(2) David Barr's beneficial ownership is based on the direct and indirect
beneficial ownership of these shares by Warburg Pincus Private Equity VIII, L.P.
("WPVIII") and Warburg Pincus International Partners, L.P. ("WPIP"). Prior to
the LLC Distribution (as defined below), as reported by this Form 4, (i) WPVIII
was the direct record owner of 2,211,332 shares of Polypore International, Inc.
Common Stock ("Common Stock") and WPIP was the direct record owner of 2,211,332
shares of Common Stock and (ii) by virtue of their position as the two managing
members of PP Holding, LLC, WPVIII and WPIP may each have been deemed to be the
beneficial owner of an additional 20,884,264 shares of Common Stock.

On May 22, 2008, PP Holding, LLC distributed an aggregate of 10,442,132 shares
of Common Stock to its members (the "LLC Distribution"), including 5,159,775
shares of Common Stock to each of WPVIII and WPIP as well as an aggregate of
122,582 shares of Common Stock to the remaining members, which distribution was
made on a pro rata basis with no consideration being paid to PP Holding, LLC in
connection therewith. Following the LLC Distribution, WPVIII and WPIP are each
direct record holders of 7,371,107 shares of Common Stock and may each be deemed
to be the beneficial owner of an additional 10,442,132 shares of Common Stock of
which PP Holding, LLC is the direct record holder.

Mr. Barr is a general partner of Warburg, Pincus & Co., which is the manager of
Warburg Pincus Partners LLC, which is the general partner of WPVIII and WPIP.
Mr. Barr is also a managing director and member of Warburg Pincus LLC, which is
the manager of WPVIII and WPIP. As such, Mr. Barr may be deemed to have an
indirect pecuniary interest (within Rule 16a-1 of the Exchange Act) in an
indeterminate portion of these shares beneficially owned by WPVIII and WPIP. Mr.
Barr disclaims beneficial ownership of such shares except to the extent of any
indirect pecuniary interest therein. Mr. Barr does not directly own any shares
of common stock.