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Studies on the steady and dynamic rheological properties of poly(dimethyl‐siloxane) filled with calcium carbonate based on superposition of its relative functions
Author(s) -
Xu Xiaoming,
Tao Xiaole,
Gao Chuanhua,
Zheng Qiang
Publication year - 2007
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.27256
Subject(s) - superposition principle , rheology , materials science , shear modulus , polydimethylsiloxane , time–temperature superposition , calcium carbonate , volume fraction , percolation (cognitive psychology) , composite material , percolation threshold , shear rate , percolation theory , thermodynamics , polymer , chemistry , physics , conductivity , quantum mechanics , neuroscience , biology , electrical resistivity and conductivity
The steady and dynamic rheological properties of hydroxyl‐terminated polydimethylsiloxane filled with calcium carbonate were investigated by varying the filler volume fraction (Φ) from 0 to 18.2 vol %. The results reveal that there exists a “percolation threshold” (Φ c = 3.6%) for the suspensions, below which both the “Cox‐Merz” and modified “Cox‐Merz” rule are competent over the whole shear regions. However, these two rules breakdown and a characteristic plateau appears in low frequency regions for suspensions with Φ > Φ c . The reasons for this can be ascribed to the contributions of nonhydrodynamic forces and formation of percolated filler network structure with increasing Φ. Moreover, using a concentration‐dependent parameter, B (Φ), superposition curves of dynamic complex modulus (| G *|) and shear stress (τ) for all suspensions were obtained through shifting | G *| curves along the ordinate and τ functions along the abscissa using different B (Φ) as shifting factor. Unfortunately, the reasonable superposition range is restricted in the high ω or $\dot \gamma$ regions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008