Flow-induced alignment in injection molding of fiber-reinforced polymer composites

Papathanasiou, T. D.; Kuehnert, Ines; Polychronopoulos, Nickolas D.

doi:10.1016/b978-0-12-818574-2.00001-4

Cited by 8 publications

(2 citation statements)

References 173 publications

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“…This intricate interplay creates a feedback loop that may result in a scenario where a single gate predominantly controls the packing. This phenomenon, known as “underflow” or “backflow,” 26 causes internal displacement of the weld surface, also impacting the fiber orientation at the weld line.…”

Section: Resultsmentioning

confidence: 99%

Investigation of microstructural and mechanical properties of weld lines in injection‐molded short glass fiber‐reinforced polyamide 6

Mokarizadehhaghighishirazi,

Buffel,

Lomov

et al. 2024

Polymer Composites

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This research investigates the impact of weld lines on the mechanical properties and fracture behavior of injection‐molded unfilled and glass fiber‐reinforced polyamide 6 (PA6). The study aims to predict the weld line strength by analyzing the composite's microstructure at the weld line and investigating the influence of injection molding parameters. While weld lines had minimal effects in unfilled PA6 thanks to the matrix's high healing capability, composite samples showed reduced mechanical properties due to unfavorable fiber orientation at the weld line. Fracture surfaces revealed a bell‐shaped structure linked to the ‘underflow’ process caused by flow imbalances during injection molding. This phenomenon impacts fiber orientation at the weld line, affecting mechanical properties. The ‘underflow’ is simulated using Autodesk Moldflow®, predicting enhanced fiber alignment along the flow direction. Regarding processing parameters, both melt and mold temperatures showed negligible impacts, while enhanced mechanical properties were observed at elevated packing pressures. The analysis of fracture surfaces showed intensified “underflow” with increased packing pressure. A relationship is established between weld line strength and fiber orientation at the weld line, potentially serving as a predictive tool for estimating weld line strength.Highlights Weld lines in unfilled PA6:Negligible impact on the mechanical properties. In the PA6 composite: significant drop due to unfavorable fiber orientation. Fracture behavior of the composite: Bell‐shaped weld line linked to “underflow.” Melt and mold temperature: minor effect; packing pressure enhances properties. Correlation established between the weld line strength and fiber orientation.

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Section: Resultsmentioning

confidence: 99%

Investigation of microstructural and mechanical properties of weld lines in injection‐molded short glass fiber‐reinforced polyamide 6

Mokarizadehhaghighishirazi,

Buffel,

Lomov

et al. 2024

Polymer Composites

View full text Add to dashboard Cite

show abstract

“…Injection molding is a process that heats and melts polymers, metals, and other materials and uses pressure to inject them into the mold for cooling molding. 34,35 H. Massé et al 34 included an overview of the injection molding process, the primary characteristics of the ow patterns during lling that were relevant to bre orientation, and a review of experimental observations of bre orientation in injection-molded parts, 25 Injection molding 4 1.8 26 --PEEK 26 Selective laser sintering 0.5 3.15 107 7.7 × 10 −9 -PEEK 27 Hot pressing molding 3 3.07 106.2 0.1 -PEKK 28 Spark plasma sintering 5 --16.4 -PEKK 29 Hot pressure molding 2 3.07 186 --PEKK 30 Electromagnetic molding 3.8 ----including bre orientation around weld lines. Finally, an outline of modeling techniques used in the prediction of bre orientation in injection molding is presented.…”

Section: Injection Moldingmentioning

confidence: 99%