Exhibit 99.1

                            Explanation of Responses

(2) Prior to the LLC Distribution (as defined below), as reported by this Form
4, (i) Warburg Pincus Private Equity VIII, L.P. ("WPVIII") was the direct record
owner of 2,211,332 shares of Polypore International, Inc. Common Stock (Common
Stock") and (ii) by virtue of its position as one of two managing members of PP
Holding, LLC, WPVIII may 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 WPVIII, 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 is the direct record holder of
7,371,107 shares of Common Stock and may 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.

The sole general partner of WPVIII is Warburg Pincus Partners LLC, a New York
limited liability company ("WPP LLC"). Warburg Pincus & Co., a New York general
partnership ("WP"), is the sole member of WPP LLC. Warburg Pincus LLC, a New
York limited liability company ("WP LLC"), manages WPVIII. Charles R. Kaye and
Joseph P. Landy are each Managing General Partners of WP and Co-Presidents and
Managing Members of WP LLC. The members of WP LLC are substantially the same as
the partners of WP. By reason of the provisions of Rule 16a-1 of the Securities
Exchange Act of 1934, WP, WP LLC, WPP LLC, Mr. Kaye and Mr. Landy may be deemed
to be the beneficial owners of Common Stock held by WPVIII. Each of WP, WP LLC,
WPP LLC, Mr. Kaye and Mr. Landy all disclaim beneficial ownership of all shares
of Common Stock except to the extent of any indirect pecuniary interest therein.