A study on a perfluoropolymer purification and its application to membraneformation

in this work, a study on a perfluoropolymer purification with crossflow MF and UF, using commercial membranes, has been carried out. Copolymers of tetrafluoroethylene (TFE) and 2,2,4trifluoro, 5trifluorometox y 1,3 dioxide (TTD), known commercially as HYFLON(R) AD, are highly transpa rent to light from deep UV to near infrared, so they find applications in o ptic and electronic industries, such as plastic optical fibers (POF), anti- reflective coating and protective pellicles in manufacturing semi-conductor . For the above application, it is often crucial to avoid the presence of b oth suspended and dissolved contaminants in the polymer and polymeric solut ions. Membranes made from this amorphous perfluoropolymer were prepared in flat s heet, tubular and hollow fiber forms. Tests of membrane hydrophobic charact er and of pure gas permeability were carried out. Experimental gas separation data obtained with membranes prepared with TTD- TFE co-polymers and data from the literature on membranes made with co-poly mers of perfluoro2.2dimethyldioxide (PDD) and TFE, commercially known as TE FLON(R) AE revealed an interesting linear relationship between permeation a nd glass transition temperature T-g. The voids volume fraction (Phi(v)) of the above amorphous perfluoropolymers was also estimated from the difference between the experimental polymer de nsity and a theoretical density obtained by simple calculations using the g roup contribution method, (C) 1999 Elsevier Science B.V. All rights reserve d.