Bubble morphological evolution and surface defect formation mechanism in the microcellular foam injection molding process

Zhang, Lei; Zhao, Guoqun; Dong, Guohai; Li, Shuai; Wang, Guilong

doi:10.1039/c5ra07512b

Cited by 25 publications

(8 citation statements)

References 51 publications

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“…However, the stress perpendicular to the melt-draw direction increases as the melt-draw ratios increase. The EVOH island structure gradually changes from a spherical shape to an elliptical shape, and the deformation parameter ( D ) of EVOH islands in the annealed PP/EVOH hollow fibers are obtained by the following equation where L is the long axis of EVOH islands along the draw direction and S is the short axis of the EVOH islands perpendicular to the draw direction.…”

Section: Resultsmentioning

confidence: 99%

Structure Regulation of Polypropylene/Poly(ethylene-co-vinyl alcohol) Hollow Fiber Membranes with a Bimodal Microporous Structure Prepared by Melt-Spinning and Stretching: The Role of Melt-Draw Ratio

Luo

Sun

Gao

et al. 2021

Ind. Eng. Chem. Res.

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High-performance polymeric hollow fiber membranes fabricated by a green and sustainable route have become the direction of the future. The bimodal microporous structure was green formed via melt spinning−stretching in the polypropylene (PP)/poly(ethylene-co-vinyl alcohol) (EVOH) hollow fiber membranes (PP/EVOH-HFMs) for improving the porosity and retaining the rejection performance. The relationship between the PP lamellar microstructure, the two-phase interface area, and the EVOH island morphology in PP/EVOH hollow fibers and the bimodal microporous structure in PP/EVOH-HFMs under different melt-draw ratios was established. The pore size of the bimodal microporous structure was controlled by regulating the melt-draw ratio. Small micropore sizes increased from 95 to 183 nm, and large micropore sizes decreased gradually from 3916 to 1054 nm with the melt-draw ratios increased. The porosity and pure water flux of PP/EVOH-HFM reached the maximum when the melt-draw ratio was 6000%. Moreover, the models of phase morphology and microstructure of PP/EVOH blends, PP/EVOH hollow fibers, and PP/EVOH-HFMs were built to explain the regulation mechanism of melt-draw ratio on the bimodal microporous structure of membranes.

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Section: Resultsmentioning

confidence: 99%

Structure Regulation of Polypropylene/Poly(ethylene-co-vinyl alcohol) Hollow Fiber Membranes with a Bimodal Microporous Structure Prepared by Melt-Spinning and Stretching: The Role of Melt-Draw Ratio

Luo

Sun

Gao

et al. 2021

Ind. Eng. Chem. Res.

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“…The idea of PIMPLE algorithm is that the subrelaxation in every time step to obtain a bigger time step (same with the SIMPLE algorithm), and the multiple pressure corrections of PISO is used to fully solve the coupled problem of pressure and velocity in every iteration step. The specific calculation process is detailed described in ref . According to experimental design of injection process, the parameter values of numerical example on boundaries are shown in Table .…”

Section: Modeling and Simulationmentioning

confidence: 99%

Foaming Mechanism of Polypropylene in Gas-Assisted Microcellular Injection Molding

Hou

Zhao

Zhang

et al. 2018

Ind. Eng. Chem. Res.

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In our recent study, it is reported that gas-assisted microcellular injection molding (GAMIM) is a promising method to fabricate plastic foams with good surface quality, high weight reduction, and improved mechanical performance. To clarify the foaming mechanism, the crystallization behaviors of polypropylene in both conventional injection molding (CIM) and gas-assisted injection molding (GAIM) were studied. It is found that GAIM can significantly promote melt crystallization and refine crystals. To explore the improvement mechanism of crystallization, a numerical model was developed to simulate the filling and cooling processes of CIM and GAIM. The simulation results show that the much stronger shear field and the faster cooling rate lead to the refinement of crystals in GAIM. Finally, a crystallization-driven cell nucleation model was proposed to explain the improved foaming behavior of polypropylene in GAMIM. This paper provides a deep understanding of the foaming behavior and hence benefits the foaming process design.

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“…The causes of surface defects while foaming have been studied in depth. In fact, attempts to develop numerical simulation models have been made for predicting the surface quality of molded parts [107]. As the surface layer is formed inside the mold cavity, different technologies concerning the tool have been introduced to improve the surface quality of foamed polymers [108].…”

Section: Complementary Tool Technologiesmentioning

confidence: 99%

Characterization of microcellular plastics for weight reduction in automotive interior parts

Monterde¹

2017

Kunststoffe Im Automobilbau 2017

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Bubble morphological evolution and surface defect formation mechanism in the microcellular foam injection molding process

Abstract: A multiphase model was established to simulate the bubble morphological evolution in MFIM, and a new phenomenon of surface collapse and pits with the gradient depth was discovered.

Cited by 25 publications

References 51 publications

Structure Regulation of Polypropylene/Poly(ethylene-co-vinyl alcohol) Hollow Fiber Membranes with a Bimodal Microporous Structure Prepared by Melt-Spinning and Stretching: The Role of Melt-Draw Ratio

Structure Regulation of Polypropylene/Poly(ethylene-co-vinyl alcohol) Hollow Fiber Membranes with a Bimodal Microporous Structure Prepared by Melt-Spinning and Stretching: The Role of Melt-Draw Ratio

Foaming Mechanism of Polypropylene in Gas-Assisted Microcellular Injection Molding

Characterization of microcellular plastics for weight reduction in automotive interior parts

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