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The rheology and mold flow of polyester sheet molding compound
Author(s) -
Lee L. J.,
Marker L. F.,
Griffith R. M.
Publication year - 1981
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.750020412
Subject(s) - extensional viscosity , materials science , sheet moulding compound , composite material , rheology , molding (decorative) , shear (geology) , viscosity , shear flow , mold , transfer molding , extensional definition , composite number , shear rate , shear viscosity , mechanics , geology , paleontology , physics , tectonics
Flow properties of sheet molding compounds (SMC) were measured by several rhemeters. Shear viscosities of SMC paste can be fitted by the Carreau viscosity equation and reduced to a single master curve by plotting the reduced shear viscosity (η/η 0 ) against reduced shear rate ( \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} η 0 / T ). The deformation fo glass filled compounds under extensional forces. When the shear forced was applied, the compound defomed like a deck of cards being slid. It behaved essentially like a laminate of many layers. On the other hand, SMC compounds elongated much less before sample failure occurred under the extensional flow. The extensional viscosity was much higher than the shear viscosity. This phenomenon was explained by a solid composite theory and theories developed from local shear flows between adjacent fibers. The flow of SMC compounds during molding showed that the surface layers flowed further than the inner layers when the mold surfaces were hot. This casued inner plies to show through at the surface and resulting in some wavy glass orientation. This phenomenon was explained equalitatively by a heat penetration model.

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