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Experimental determination of concentration‐dependent carbon dioxide diffusivity in LDPE
Author(s) -
Tendulkar J.,
Upreti S. R.,
Lohi A.
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.29059
Subject(s) - thermal diffusivity , low density polyethylene , thermodynamics , isothermal process , carbon dioxide , mass transfer , diffusion , work (physics) , polymer , materials science , gaseous diffusion , polyethylene , chemistry , organic chemistry , physics , composite material , electrode
In this work, we experimentally determine the concentration‐dependent diffusivity of carbon dioxide in low‐density poly(ethylene) (LDPE). For this purpose, experiments are carried out to obtain pressure‐decay data for isothermal diffusion of the gas in the polymer. Based on a detailed mass transfer model, variational calculus is used to establish the conditions necessary to yield the concentration‐dependent diffusivity that enables the model‐predicted mass of absorbed gas in polymer to match with the experimental counterpart. A computational algorithm is implemented to solve the model and the conditions and obtain the diffusivities. Determined at 120 and 130°C for four different pressures in the range 0.352 to 1.232 MPa, the diffusivities are strong unimodal functions of gas concentration in polymer and of the order 10 −9 m 2 s −1 . Mathematical correlations are developed to calculate the diffusivity at a given temperature, pressure, and gas concentration. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009