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Molecular orientation in injection molding
Author(s) -
Tadmor Z.
Publication year - 1974
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.1974.070180614
Subject(s) - materials science , heat transfer , shear flow , orientation (vector space) , relaxation (psychology) , flow (mathematics) , amorphous solid , shear (geology) , front (military) , polymer , molding (decorative) , mechanics , macromolecule , composite material , chemical physics , thermodynamics , chemistry , crystallography , physics , geometry , psychology , social psychology , biochemistry , mathematics , meteorology
A semiquantitative model is proposed to explain the complex molecular orientation distribution, observed in injection moldings of amorphous polymers. The model incorporates flow and heat transfer mechanisms coupled with molecular theories. The orientation in the surface skin is related to steady elongational flow in the advancing front, whereas the orientation in the core is related to the shear flow, behind the front, between two solidyfying layers. Coupled with the elongational and shear‐induced orientations, a molecular relaxation process takes place which is determined by the rate of heat transfer. The bead‐and‐spring macromolecular theory was used to calculate root mean end‐to‐end distances of macromolecules in the various flow fields, as well as the relaxation process.