SOLUTION SPINNING OF FIBERS WITH ORIENTED POROSITY

The preparation of porous fibers from the quasi-ternary system poly(me thyl methacrylate)/poly(ethyl methacrylate)-1-butanol is based on the combination of different liquid-liquid demixing processes that interfe re with the vitrification process. Polymer-polymer demixing takes plac e at high temperature and interferes at lower temperature with polymer -solvent demixing and the vitrification of some of the formed phases. When these processes take place during extrusion, porous ''composite'' fibers are obtained. They consist of fibrils of poly(methyl methacryl ate) coated with poly(ethyl methacrylate), and these fibrils are separ ated by micrometer-sized channels that extend along the fiber axis. Th e formation of these fibers is discussed within the framework of the p hase behavior of the quasi-ternary system. (C) 1996 John Wiley & Sons, Inc.