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Self‐interference flow of an isotactic polypropylene melt in a cavity during injection molding. I. Effect of the self‐interference flow on the properties
Author(s) -
Dai Wenli,
Liu Pengsheng,
Wang Xiayu
Publication year - 2003
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.12052
Subject(s) - materials science , melt flow index , composite material , ultimate tensile strength , shrinkage , polypropylene , molding (decorative) , mold , izod impact strength test , tacticity , flow (mathematics) , modulus , injection moulding , polymer , mechanics , polymerization , physics , copolymer
The self‐interference flow (SIF) of a melt in a cavity during injection molding is introduced. It comes from two streams of the melt being split by a patented mold gate called a twin gate. The effects of this flow on the static and dynamic mechanical properties, thickness distribution, and shrinkage in the transverse direction (TD) of injection‐molded isotactic polypropylene parts are discussed. SIF has an influence on the static mechanical properties, especially the impact strength. There are slight increases in the tensile strength and Young's modulus and an increase of approximately 70–90% in the impact strength in comparison with the properties of samples obtained by a conventional flow process with a common pin gate. Dynamic mechanical thermal analysis studies show an increase in the storage modulus for SIF samples. Results obtained from research into the effect of the mold temperature and injection pressure on the impact strength show that the impact strength of SIF specimens has a weaker dependence on the mold temperature and injection pressure. In addition, the flow brings a more uniform thickness distribution and a smaller shrinkage in the TD to SIF samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2784–2790, 2003