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Morphology and mechanical properties of injection molded articles with weld‐lines
Author(s) -
Kim Jin Kon,
Song Ju Ho,
Chung S. T.,
Kwon T. H.
Publication year - 1997
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.11665
Subject(s) - weld line , materials science , ultimate tensile strength , welding , elongation , perpendicular , composite material , fiber , line (geometry) , flow (mathematics) , mechanics , geometry , mathematics , physics
Abstract The effect of weld‐lines on the morphology and mechanical properties of injection molded articles made of neat poly(butylene terephthalate) (PBT) and glass fiber‐reinforced PBT was investigated. The weld‐line was introduced to a molded article by using a rectangularly shaped insert inside a mold cavity, and tensile specimens were prepared at various positions through the entire molded article. The weld‐line position was further checked by a short‐shot experiment. Although the maximum tensile stress for specimens of neat PBT with a weld‐line is almost the same as that without a weld‐line, the maximum tensile stress and the elongation at break for fiber‐reinforced PBT with a weld‐line were found to be about half of those without the weld‐line. This is attributed to the fact that the fibers near the weld‐lines are oriented parallel to the weld‐line direction (or perpendicular to the tensile force direction) due to stretching flow. Finally, we compared experimental results of flow pattern and fiber orientations with numerical simulations. We found that the predictions of flow fronts and fiber orientations are in good agreement with experimental results.