Richard Mandell was appointed Thursday as president and chief executive officer of Hampshire Group Ltd., the sweater and sportswear supplier. Mandell, who has been a director of the company since April 2008 and also serves on the boards of Encore Capital Group and Trian Acquisition I Corp., succeeds Michael Culang, who resigned. Additionally, Heath Golden, most recently vice president of administration and general counsel, was promoted to executive vice president and chief operating officer. Efrem Gerszberg’s NAF Acquisition Corp. faces a 5 p.m. deadline today to complete its cash tender offer to take over Hampshire after failing to acquire the 82 percent of Hampshire’s shares necessary to complete the transaction by March 31. Should the deal be consummated, NAF would merge into Hampshire.