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Birefringence prediction of optical media
Author(s) -
Fan Bingfeng,
Kazmer David O.,
Bushko Wit C.,
Theriault Richard P.,
Poslinski Andrew J.
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.20073
Subject(s) - birefringence , materials science , polycarbonate , flow birefringence , isothermal process , composite material , mold , polystyrene , viscoelasticity , flow (mathematics) , stress (linguistics) , optics , polymer , mechanics , thermodynamics , linguistics , philosophy , physics
The flow and thermally induced birefringence of injection‐compression molded optical media such as compact discs and digital video discs is predicted by applying a stress‐optical rule to the flow and thermally induced stresses, which are estimated with a viscoelastic material model integrated into a non‐isothermal compressible flow simulation. The resulting model considers flow and cooling induced molecular orientation, and the transient effect of thermal stress and pressure. Contrary to previous research for polystyrene, the validated results indicate that, for polycarbonate, the magnitude of the thermally induced birefringence is comparable to the flow induced birefringence. Simulation results of the flow and thermally induced in‐plane birefringence for compact‐disc‐recordable moldings with an optical grade of polycarbonate compared well with experimental observations at different mold and melt temperatures. Both simulation and experiments indicate that mold and melt temperatures have a significant effect on the level of birefringence; increasing mold or melt temperature significantly reduces the birefringence. Polym. Eng. Sci. 44:814–824, 2004. © 2004 Society of Plastics Engineers.