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Competitive sorption of water vapor and CO 2 in photocrosslinked PVCA film for a capacitive‐type humidity sensor
Author(s) -
Matsuguchi Masanobu,
Maeda Nozomi,
Sakai Yoshiro
Publication year - 2001
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.10062
Subject(s) - sorption , water vapor , relative humidity , adsorption , langmuir , langmuir adsorption model , vapor pressure , analytical chemistry (journal) , chemistry , humidity , freundlich equation , quartz crystal microbalance , materials science , chromatography , thermodynamics , organic chemistry , physics
The sorption behavior of water vapor and CO 2 gas in photocrosslinked poly(vinyl cinnamate) (PVCA) film was examined at 30°C under atmospheric pressure. Both the water sorption isotherm and the CO 2 sorption isotherm obtained with quartz crystal microbalance (QCM) method obeyed the simple Langmuir's equation. Water vapor/CO 2 mixed‐gas sorption isotherms were also obtained. Total amount of sorbed mixed gases was clearly influenced by the partial pressure of water vapor ( p w ) and CO 2 gas ( p c ) in the atmosphere. A modified Langmuir's equation based on a dual‐site model was employed for predicting the competitive adsorption isotherm, and the isotherm was clearly described by the equation. The theoretically estimated amount of adsorbed water at the constant p w decreased slightly with increasing p c . The effect of this phenomenon on the sensitivity of the capacitive‐type relative humidity sensor was examined. As expected, the electrical capacitance of the sensor at the constant relative humidity decreased because of the coexistence of CO 2 gas. However, the influence was quite small in the CO 2 concentration range in the ordinary environment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 401–407, 2002