Diffusion coefficients of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in polydimethylsiloxane and low‐density polyethylene polymers

Abstract

AbstractDiffusion coefficients (D) of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were determined by film‐stacking technique in low‐density polyethylene (LDPE) and two types of polydimethylsiloxane (PDMS) (also known as silicone rubber, SR) with the trade names AlteSil™ and Silastic®. The estimated values of D for PCBs and PAHs over a wide range of hydrophobicity were 2–2.5 orders of magnitude lower in LDPE than in SR polymers. Log D (m2 s−1) of PCBs ranged from −10.1 to −10.9 for SRs and from −12.4 to −13.7 for LDPE. For PAHs these ranges were −9.8 to −11.4 for SRs and −11.9 to −13.7 for LDPE. Compared with the D values calculated in water, D were 1–2 and 3–4 orders of magnitude lower in SR and LDPE, respectively. For PAH molecules, D was lower than for PCBs with a similar molecular weight, probably because of their more rigid structure. The range of log D for PCBs in SR was only 0.5 log units (factor of 3.2) versus 1.2 log units (factor of 16) in LDPE. Although compound classes showed different relations, a linear relation of D with total surface area was the most universal. This relation may be used for prediction of D values in SR and LDPE polymers for other organic compounds. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010