Assisted permeation through surface fluorinated polymers

The permeation rates of constituent components of toluene and methanol mixt ures through surface fluorinated, fluoroxidized and unmodified HDPE was mea sured using a new how through chamber, GC-based technique. The polymer syst ems demonstrated assisted permeation wherein the presence of one component increased the permeation rate of a second minor component. The presence of 1000 ppm of methanol in the solvent mixture increased the permeation rate t hrough the fluoroxidized composite by over an order of magnitude. For the u nmodified HDPE, the activity adjusted toluene permeability (P-toluene) rema ined virtually constant, independent of the methanol concentration. Swellin g due to the presence of toluene in the plastic for the unmodified HDPE cas e increased the methanol permeability by three orders of magnitude. The P-t oluene for the surface fluoroxidized composite was determined to be 1.5+/-0 .4x10(-7) cm(2) s(-1) (cm Hg)(-1) and the P-toluene for the surface fluorox idized layer was found to be 1.1+/-0.4x10(-9) cm(2) s(-1) (cm Hg)(-1), an 8 50-fold decrease in permeability relative to the untreated HDPE. The long t erm P-toluene for the fluorinated composite was found to be 0.6+/-0.3x10(-7 ) cm(2) s(-1) (cm Hg)(-1) (C) 2000 Elsevier Science S.A. All rights reserve d.