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Shear‐induced migration of conductive fillers in injection molding
Author(s) -
Hong ChangMin,
Kim Jongdae,
Jana Sadhan C.
Publication year - 2004
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20215
Subject(s) - materials science , composite material , polypropylene , conductivity , percolation threshold , polystyrene , molding (decorative) , shear (geology) , carbon black , compression molding , volume fraction , electrical conductor , polymer , electrical resistivity and conductivity , mold , chemistry , natural rubber , engineering , electrical engineering
The effect of shear‐induced conductive filler migration on surface and volume conductivity of injection molded articles of polystyrene and polypropylene with carbon black was investigated. It was found that the loss of conductivity was most significant when the mean particle concentration was at or slightly above the percolation threshold. The compounds with mean particle concentration well above the percolation threshold showed no loss at all. The conductivity decreased with the increase of shear rate used in molding. The removal of surface layers by excimer laser led to restoration of the conductivity to the value of well‐mixed, compression‐molded specimens. The thickness of surface layer removed before conductivity was restored was found to be a strong function of the shear rate and the nature of polymer used. Polym. Eng. Sci. 44:2101–2109, 2004. © 2004 Society of Plastics Engineers.