The injection molding process is successfully applied to the production of polymer parts in several fields, from transportation to biomedice. Short processing times and high dimensional accuracy are the main factors promoting its diffusion. Fast cavity heating cycles contribute to enhancing the part accuracy at the micrometrical level, duration, and the mechanical properties. The advantages of cavity temperature modulation lead to a great interest in process simulation in the presence of a heating device. However, only a few works focus on the prediction of morphology development during the process. In semicrystalline parts, the morphology is composed of spherulites at the core and fibrils at the surface; the fibrils formation is marginally explored, although determining the mechanical performances. In this work, a two-step approach is proposed to predict fibril formation in the case of a well-characterized polypropylene. The first step describes temperature and flow fields during the process; the second step adopts the outputs of the first one for describing fibril formation. Several temperature cycles are selected for the cavity surface, and two pressures are selected for the packing stage. The simulation outputs for temperature, pressure evolutions, and morphology distributions, successfully compare with the experimental findings.

Prediction of Morphology Distribution within Injection Molded Parts Obtained with Fast Cavity Heating Cycles: Effect of Packing Pressure

Speranza, V;Liparoti, S
;
Pantani, R
2022

Abstract

The injection molding process is successfully applied to the production of polymer parts in several fields, from transportation to biomedice. Short processing times and high dimensional accuracy are the main factors promoting its diffusion. Fast cavity heating cycles contribute to enhancing the part accuracy at the micrometrical level, duration, and the mechanical properties. The advantages of cavity temperature modulation lead to a great interest in process simulation in the presence of a heating device. However, only a few works focus on the prediction of morphology development during the process. In semicrystalline parts, the morphology is composed of spherulites at the core and fibrils at the surface; the fibrils formation is marginally explored, although determining the mechanical performances. In this work, a two-step approach is proposed to predict fibril formation in the case of a well-characterized polypropylene. The first step describes temperature and flow fields during the process; the second step adopts the outputs of the first one for describing fibril formation. Several temperature cycles are selected for the cavity surface, and two pressures are selected for the packing stage. The simulation outputs for temperature, pressure evolutions, and morphology distributions, successfully compare with the experimental findings.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11386/4806713
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