Apparatus (100, 101, 102) and die cartridge assembly (18, 44, 45, 47) adapted for use with same for producing fibrous material (212). The apparatus (100) comprises a removably attachable die cartridge assembly (18) that adapts to conventional spunmelt equipment. The die cartridge assembly (18) is removably positionable beneath an extrusion body (10) for effecting formation of fibrous material by fibrillation of polymer films. The cartridge assembly (18) includes at least one polymer passage (19) communicating with a molten polymer source (10) for directing molten polymer onto at least one film forming surface (20, 28) defined by the cartridge assembly (18), and also defines at least one gas passage (222, 22, 30) communicating with a gas source (16) for directing pressurized gas (220) against the molten polymer (210) in the form of a film for effecting formation of the fibrous material (212).