Influence of the flow rate on the die swell for polymer micro coextrusion process

A numerical model for a polymer double-layer single lumen microtubes coextrusion flow was constructed and the finite element method was used for numerical solution. The distribution of the velocity, pressure, shear rate, etc., were analyzed, as well as the relationship between the normal stress diff...

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Main Authors: Deng Xiaozhen, Ji Haibo, Liu Biao, Liu Qiang, Xiao Bing, Ren Zhong, Xu Fang, Fan Li
Format: Article
Language:English
Published: De Gruyter 2025-06-01
Series:e-Polymers
Subjects:
Online Access:https://doi.org/10.1515/epoly-2024-0107
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author Deng Xiaozhen
Ji Haibo
Liu Biao
Liu Qiang
Xiao Bing
Ren Zhong
Xu Fang
Fan Li
author_facet Deng Xiaozhen
Ji Haibo
Liu Biao
Liu Qiang
Xiao Bing
Ren Zhong
Xu Fang
Fan Li
author_sort Deng Xiaozhen
collection DOAJ
description A numerical model for a polymer double-layer single lumen microtubes coextrusion flow was constructed and the finite element method was used for numerical solution. The distribution of the velocity, pressure, shear rate, etc., were analyzed, as well as the relationship between the normal stress difference, secondary flow, and die swell were explored. Then, the influence of the flow velocity difference on the die swell of the double-layer microtubes was revealed. The research results indicate that, in the traditional coextrusion process, the melts will undergo expansion and deformation after leaving the die. And the velocity difference caused by the increase in the outer layer melt velocity will cause the outer layer to squeeze the inner layer, resulting in an uneven wall thickness of the composite microtubes. In the gas-assisted coextrusion process, the distribution of the velocity, pressure, shear rate, etc., can be effectively improved. However, the extrusion deformation between the melt layers caused by the velocity difference cannot be eliminated. That is, the gas-assisted technology can effectively improve the overall shape and size accuracy of composite microtubes, but cannot solve the problem of uneven wall thickness caused by the velocity difference.
format Article
id doaj-art-b3e5effac97b49d2bbf44eec43a2a8d8
institution DOAJ
issn 1618-7229
language English
publishDate 2025-06-01
publisher De Gruyter
record_format Article
series e-Polymers
spelling doaj-art-b3e5effac97b49d2bbf44eec43a2a8d82025-08-20T02:40:18ZengDe Gruytere-Polymers1618-72292025-06-01251545710.1515/epoly-2024-0107Influence of the flow rate on the die swell for polymer micro coextrusion processDeng Xiaozhen0Ji Haibo1Liu Biao2Liu Qiang3Xiao Bing4Ren Zhong5Xu Fang6Fan Li7Jiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Advanced Electronic Materials and Devices, Jiangxi Science and Technology Normal University, Nanchang, 330038, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaJiangxi Provincial Key Laboratory of Precision Drive and Equipment/School of Mechanical Engineering, Nanchang Institute of Technology, Nanchang, 330099, ChinaA numerical model for a polymer double-layer single lumen microtubes coextrusion flow was constructed and the finite element method was used for numerical solution. The distribution of the velocity, pressure, shear rate, etc., were analyzed, as well as the relationship between the normal stress difference, secondary flow, and die swell were explored. Then, the influence of the flow velocity difference on the die swell of the double-layer microtubes was revealed. The research results indicate that, in the traditional coextrusion process, the melts will undergo expansion and deformation after leaving the die. And the velocity difference caused by the increase in the outer layer melt velocity will cause the outer layer to squeeze the inner layer, resulting in an uneven wall thickness of the composite microtubes. In the gas-assisted coextrusion process, the distribution of the velocity, pressure, shear rate, etc., can be effectively improved. However, the extrusion deformation between the melt layers caused by the velocity difference cannot be eliminated. That is, the gas-assisted technology can effectively improve the overall shape and size accuracy of composite microtubes, but cannot solve the problem of uneven wall thickness caused by the velocity difference.https://doi.org/10.1515/epoly-2024-0107polymer double-layer microtubesgas-assisted micro coextrusiondie swellvelocity differencefinite element method
spellingShingle Deng Xiaozhen
Ji Haibo
Liu Biao
Liu Qiang
Xiao Bing
Ren Zhong
Xu Fang
Fan Li
Influence of the flow rate on the die swell for polymer micro coextrusion process
e-Polymers
polymer double-layer microtubes
gas-assisted micro coextrusion
die swell
velocity difference
finite element method
title Influence of the flow rate on the die swell for polymer micro coextrusion process
title_full Influence of the flow rate on the die swell for polymer micro coextrusion process
title_fullStr Influence of the flow rate on the die swell for polymer micro coextrusion process
title_full_unstemmed Influence of the flow rate on the die swell for polymer micro coextrusion process
title_short Influence of the flow rate on the die swell for polymer micro coextrusion process
title_sort influence of the flow rate on the die swell for polymer micro coextrusion process
topic polymer double-layer microtubes
gas-assisted micro coextrusion
die swell
velocity difference
finite element method
url https://doi.org/10.1515/epoly-2024-0107
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