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Formation mechanism of hierarchically crystalline structures under coupled external fields in multi-melt multi-injection molding: Simulation and experiment.

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Title: Formation mechanism of hierarchically crystalline structures under coupled external fields in multi-melt multi-injection molding: Simulation and experiment.
Authors: Chen, Li-Bo1 (AUTHOR), Huang, Yan-Hao1 (AUTHOR), Liu, Lei1 (AUTHOR), Zhao, Xin1 (AUTHOR), Liu, Zheng-Ying1 (AUTHOR), Yang, Wei1 (AUTHOR), Yang, Ming-Bo1 (AUTHOR) yangmb@scu.edu.cn
Source: Composites: Part B, Engineering. May2020, Vol. 188, pN.PAG-N.PAG. 1p.
Subjects: Crystal structure, High density polyethylene, Finite volume method, Crystal morphology, Crystal lattices, Interface structures, Phononic crystals
Abstract: In order to clarify the formation mechanism of hierarchically crystalline structures in multi-melt multi-injection molding (M3IM), the structures around the interface were examined, as well as the shear fields and temperature fields were simulated by 3D finite volume method (3D-FVM) and volume of fluid (VOF) method. It is found that theoretically isotactic polypropylene (iPP) tends to form highly oriented superstructures when subjected a critical shear rate of about 1200 s−1 and a cooling rate of 12.5 °C⋅s−1 in the second penetration process of M3IM, while high density polyethylene (HDPE) shows some otherwise in critical conditions to form oriented morphologies in the penetrated layer, i.e., cooling rate of 10 °C⋅s−1 is inadequate for HDPE shish-kebab structures fabrication even though the shear rate surpasses 1200 s−1. This work constructs a bridge between coupled external fields analyzing which involves a multiphase interface and complicate crystal morphologies prediction under multiple melt flow in a facile way. Image 1 • Coupled external fields around the interface were simulated. • Hierarchically crystalline structures around the interface were examined. • Relationship between external fields and structural hierarchy were established. • Critical forming conditions of oriented superstructures were established. • Great significance for predicting possible crystal morphologies. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:In order to clarify the formation mechanism of hierarchically crystalline structures in multi-melt multi-injection molding (M3IM), the structures around the interface were examined, as well as the shear fields and temperature fields were simulated by 3D finite volume method (3D-FVM) and volume of fluid (VOF) method. It is found that theoretically isotactic polypropylene (iPP) tends to form highly oriented superstructures when subjected a critical shear rate of about 1200 s−1 and a cooling rate of 12.5 °C⋅s−1 in the second penetration process of M3IM, while high density polyethylene (HDPE) shows some otherwise in critical conditions to form oriented morphologies in the penetrated layer, i.e., cooling rate of 10 °C⋅s−1 is inadequate for HDPE shish-kebab structures fabrication even though the shear rate surpasses 1200 s−1. This work constructs a bridge between coupled external fields analyzing which involves a multiphase interface and complicate crystal morphologies prediction under multiple melt flow in a facile way. Image 1 • Coupled external fields around the interface were simulated. • Hierarchically crystalline structures around the interface were examined. • Relationship between external fields and structural hierarchy were established. • Critical forming conditions of oriented superstructures were established. • Great significance for predicting possible crystal morphologies. [ABSTRACT FROM AUTHOR]
ISSN:13598368
DOI:10.1016/j.compositesb.2020.107770