Study on difference of single⁃side and double⁃side gas⁃assisted technology in polymer microtubule co⁃extrusion molding

doi:10.19491/j.issn.1001-9278.2023.08.008

Abstract

Abstract:

The gas⁃assisted technology was applied for the polymer extrusion molding of a hollow double⁃layer microtubule， and the finite element method was used to analyze and study the microtubule co⁃extrusion molding process. Four different co⁃extrusion numerical models were established， which included the traditional microtube co⁃extrusion， gas⁃assisted microtube co⁃extrusion， single inner wall gas⁃assisted microtube co⁃extrusion， and single outer wall gas⁃assisted microtube co⁃extrusion. The differences in die swell rate， velocity distribution， pressure distribution， and shear rate distribution were studied. The results indicated that the double⁃side gas⁃assisted technology effectively improved the extrusion swell， uneven velocity distribution， uneven shear rate distribution， excessive pressure drop， and other problems during the hollow double⁃layer microtube extrusion process. However， the gas⁃assisted micro co⁃extrusion with a single inner wall cannot resolve the problems caused by the traditional micro co⁃extrusion， and its extrusion expansion rate was 105.41 %. The gas⁃assisted micro co⁃extrusion with a single outer wall can lead to extrusion shrinkage， and there is no improvement effect on the shear rate distribution and pressure drop.

Key words: double?layer microtubule co?extrusion molding, gas?assisted technology, single side gas?assisted extrusion, die swell

CLC Number:

TQ320.66

DENG Xiaozhen, LIU Biao, XIAO Bing, JIANG Shiyu, CHEN Tianrong. Study on difference of single⁃side and double⁃side gas⁃assisted technology in polymer microtubule co⁃extrusion molding[J]. China Plastics, 2023, 37(8): 55-60.

Figures/Tables 9

Fig.1. Geometric model of double⁃layer cylindrical microtubule and finite element model

材料

无穷剪切

黏度/Pa·s

零切黏度/

Pa·s

松弛

时间/s

非牛顿

指数

材料

参数

Tab.1. Melt parameters and Bird⁃Carreau model parameters

Fig.2. Extrusion results from different extrusion modes

Fig.3. Section view along z⁃axis at the die outlet

Fig.4. Velocity distribution at the die exit outlet

Fig.5. Velocity distribution in x direction at 5.5 mm of z⁃axis

Fig.6. Flow velocity distribution along z⁃axis

Fig.7. Shear rate distribution along x⁃axis

Fig.8. Pressure distribution of outer layer of the melt

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