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Effect of moisture absorption on the thermal properties of Bombyx mori silk fibroin films
Author(s) -
Agarwal N.,
Hoagland D. A.,
Farris R. J.
Publication year - 1997
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/(sici)1097-4628(19970118)63:3<401::aid-app17>3.0.co;2-2
Subject(s) - fibroin , silk , materials science , sericin , composite material , moisture , absorption of water , thermal , polymer science , absorption (acoustics) , polymer chemistry , thermodynamics , physics
Films of regenerated Bombyx mori silk are strongly affected by absorbed moisture, a phenomenon studied here by differential scanning calorimetry (DSC). Exposure of previously dried films to environments of controlled relative humidity produces test samples of well‐defined equilibrium moisture content. Ultimate moisture uptake is as high as 20–23% (by weight) at 75% relative humidity. The glass transition temperature, T g , drops by 40°C at moisture uptakes as low as 2%, and T g depressions as large as 140°C are observed at higher relative humidity. The moisture‐induced decrease of T g is completely reversible, as a film remoistened and then redried possesses an unchanged T g . Trends in T g with water uptake correspond reasonably well to predictions of a classical thermodynamic theory, indicating that the plasticization effect of moisture on the combined silk‐water system can be satisfactorily explained from macroscopic properties of the constituents without any reference to specific interactions. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 401–410, 1997