The solubility of gases and volatile liquids in polyethylene and polyisobutylene at elevated temperatures

摘要

AbstractThe solubility of gases and volatile liquids in low‐density polyethylene (LDPE) and polyisobutylene (PIB) at elevated temperatures has been correlated, using the experimental data available in the literature. In the present study, a Henry's constantKpat a total pressure of approximately 1 atm defined asP1=KPV 10, whereP1is the partial pressure of the solute in the vapor phase andV 10is the solubility (cm3solute/g polymer at 273.2 K and 1 atm), is correlated for nonpolar solutes with the following expressions: (1) For LDPE, ln(1/KP) = −1.561 + (2.057 + 1.438ω) (Tc/T)2; (2) For PIB, ln(1/Kp) = −1.347 + (1.790 + 1.568ω) (Tc/T)2, in which ω is the acentric factor andTcthe critical temperature of the solute. In obtaining the above correlations we have used 27 solutes covering 115 data points for LDPE, and 18 solutes covering 148 data points for PIB. We have calculated values of 1/Kpfrom the literature data reported in terms of the retention volume (V g0), weight‐fraction Henry's constant (H1), activity coefficient at infinite dilution (Ω 1∞), Flory–Huggins interaction parameter (χ), orV 10/Pobtained from high pressure sorption experiments. The correlations obtained in this study permit one to estimate with reasonable accuracy the solubility of gases and volatile liquids in either LDPE or PIB, with information on the acentric factor (ω) and critical temperature (Tc) only. The relationship for LDPE is also applicable for solubilities in high‐density polyethylene. Relationships for the heat of vaporization of solutes from infinitely dilute LDPE or PIB solutions are also derived from the