Effect of material physical parameters on gas⁃assisted coextrusion swelling for double⁃layer microtubule

doi:10.19491/j.issn.1001-9278.2024.11.015

Abstract

Abstract:

In this study， the traditional micro⁃coextrusion and gas⁃assisted micro⁃coextrusion flow models were established for double⁃layered microtubules. The effects of zero shear viscosity （ $η 0$ ）， relaxation time （ $λ$ ）， and material parameters $ε$ and $ξ$ on the die swell rate were investigated by using a numerical simulation technology. The results indicated that the die swell rate was greatly affected by $η 0$ and $λ$ in the traditional micro⁃coextrusion process. With an increase in the outer melt viscosity， the die swell rate increased from 29.15 % to 43.77 % and then tended to be stable. The die swell rate was less affected by $ε$ and $ξ$ ， and it decreased slightly with an increase in $ε$ and $ξ$ . The die swell rate varied between 37 % and 39 %. However， in the gas assisted co⁃extrusion process， the die swell rate always approached zero when $η 0$ ， $λ$ ， $ε$ and $ξ$ changed， and there was no obvious swelling or deformation phenomenon.

Key words: material physical parameter, double?layer microtubule coextrusion, gas?assisted technology, die swell

CLC Number:

TQ320.66

XIAO Bing, LIU Biao, CHEN Tianrong, JI Haibo, DENG Xiaozhen, XU Fang, ZENG Jiahang. Effect of material physical parameters on gas⁃assisted coextrusion swelling for double⁃layer microtubule[J]. China Plastics, 2024, 38(11): 87-92.

Figures/Tables 17

Fig.1. 2D structure and dimensions of the double⁃layer hollow microtubule

Fig.2. Finite element meshes of the double⁃layer hollow microtubule

	$η 0$ /Pa·s	$λ$ /s	$ε$	$ξ$	$η r$
PP	4 688	0.15	0.18	0.30	0.12
PS	2 700	0.20	0.23	0.18	0.12

	$η 0$ /Pa·s	$λ$ /s	$ε$	$ξ$	$η r$
PP	4 688	0.15	0.18	0.30	0.12
PS	2 700	0.20	0.23	0.18	0.12

Tab.1. Melt properties and PTT model parameters

黏度	第1组	第2组	第3组	第4组
$η 0 A$	2 700	5 400	8 100	10 800
$η 0 B$	2 700	2 700	2 700	2 700

黏度	第1组	第2组	第3组	第4组
$η 0 A$	2 700	5 400	8 100	10 800
$η 0 B$	2 700	2 700	2 700	2 700

Tab.2. Viscosity combination of the two polymer melt

Fig.3. Effect of melt viscosity on the microtubule swell ratio

Fig.4. Effect of melt viscosity on νx

松弛时间	第1组	第2组	第3组	第4组
$λ A$	0.1	0.2	0.4	0.6
$λ B$	0.2	0.2	0.2	0.2

松弛时间	第1组	第2组	第3组	第4组
$λ A$	0.1	0.2	0.4	0.6
$λ B$	0.2	0.2	0.2	0.2

Tab.3. Relaxation time combination of the inner and outer melt

Fig.5. Effect of relaxation time on microtubule swell ratio

Fig.6. Effect of relaxation time on νx distribution

参数	第1组	第2组	第3组	第4组
$ε A$	0.12	0.23	0.46	0.69
$ε B$	0.23	0.23	0.23	0.23

参数	第1组	第2组	第3组	第4组
$ε A$	0.12	0.23	0.46	0.69
$ε B$	0.23	0.23	0.23	0.23

Tab.4. Combination of material parameters ε of the inner and outer layer melt

参数	第1组	第2组	第3组	第4组
$ε A$	0.09	0.18	0.36	0.54
$ε B$	0.18	0.18	0.18	0.18

参数	第1组	第2组	第3组	第4组
$ε A$	0.09	0.18	0.36	0.54
$ε B$	0.18	0.18	0.18	0.18

Tab.5. Combination of material parameters ξ of the inner and outer layer melt

Fig.7. Effect of ε on swell ratio of the microtubule

Fig.8. Effect of ε on νx distribution on the outer melt wall

Fig.9. Effect of ε on νx distribution on the melt interface

Fig.10. Effect of ε on the inner and outer melt swell ratio

Fig.11. Effect of material parameters ξ on the microtubule swell ratio

Fig.12. Effect of ξ on νx distribution on the melt interface

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