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Chen SC, Lee KH, Chang CW, Hsu TJ, Feng CT. Using Gas Counter Pressure and Combined Technologies for Microcellular Injection Molding of Thermoplastic Polyurethane to Achieve High Foaming Qualities and Weight Reduction. Polymers (Basel) 2022; 14:polym14102017. [PMID: 35631900 PMCID: PMC9143106 DOI: 10.3390/polym14102017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 02/01/2023] Open
Abstract
Microcellular injection molding technology (MuCell®) using supercritical fluid (SCF) as a foaming agent offers many advantages, such as material and energy savings, low cycle time, cost-effectiveness, and the dimensional stability of products. MuCell® has attracted great attention for applications in the automotive, packaging, sporting goods, and electrical parts industries. In view of the environmental issues, the shoe industry, particularly for midsole parts, is also seriously considering using physical foaming to replace the chemical foaming process. MuCell® is thus becoming one potential processing candidate. Thermoplastic polyurethane (TPU) is a common material for molding the outsole of shoes because of its outstanding properties such as hardness, abrasion resistance, and elasticity. Although many shoe manufacturers have tried applying Mucell® processes to TPU midsoles, the main problem remaining to be overcome is the non-uniformity of the foaming cell size in the molded midsole. In this study, the MuCell® process combined with gas counter pressure (GCP) technology and dynamic mold temperature control (DMTC) were carried out for TPU molding. The influence of various molding parameters including SCF dosage, injection speed, mold temperature, gas counter pressure, and gas holding time on the foaming cell size and the associated size distribution under a target weight reduction of 60% were investigated in detail. Compared with the conventional MuCell® process, the implementation of GCP technology or DMTC led to significant improvement in foaming cell size reduction and size uniformity. Further improvement could be achieved by the simultaneous combination of GCP with DMT, and the resulting cell density was about fifty times higher. The successful possibility for the microcellular injection molding of TPU shoe midsoles is greatly enhanced.
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Affiliation(s)
- Shia-Chung Chen
- R&D Center for Smart Manufacturing, Chung Yuan Christian University, Taoyuan 32023, Taiwan; (K.-H.L.); (C.-W.C.); (T.-J.H.); (C.-T.F.)
- R&D Center for Semiconductor Carrier, Chung Yuan Christian University, Taoyuan 32023, Taiwan
- Correspondence: ; Tel.: +886-3-2652500
| | - Kuan-Hua Lee
- R&D Center for Smart Manufacturing, Chung Yuan Christian University, Taoyuan 32023, Taiwan; (K.-H.L.); (C.-W.C.); (T.-J.H.); (C.-T.F.)
| | - Che-Wei Chang
- R&D Center for Smart Manufacturing, Chung Yuan Christian University, Taoyuan 32023, Taiwan; (K.-H.L.); (C.-W.C.); (T.-J.H.); (C.-T.F.)
- R&D Center for Semiconductor Carrier, Chung Yuan Christian University, Taoyuan 32023, Taiwan
| | - Tzu-Jeng Hsu
- R&D Center for Smart Manufacturing, Chung Yuan Christian University, Taoyuan 32023, Taiwan; (K.-H.L.); (C.-W.C.); (T.-J.H.); (C.-T.F.)
| | - Ching-Te Feng
- R&D Center for Smart Manufacturing, Chung Yuan Christian University, Taoyuan 32023, Taiwan; (K.-H.L.); (C.-W.C.); (T.-J.H.); (C.-T.F.)
- R&D Center for Semiconductor Carrier, Chung Yuan Christian University, Taoyuan 32023, Taiwan
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Cao J, Wen N, Zheng Y, Chen Q. The structure, properties, and foaming of long chain branched polypropylene/clay‐supported calcium pimelate composites. POLYM ENG SCI 2022. [DOI: 10.1002/pen.25867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jing Cao
- College of Materials Science and Engineering Fuzhou University Fuzhou Fujian China
- Fujian Aton New Material Technology Co., Ltd Fuzhou Fujian China
| | - Na Wen
- College of Materials Science and Engineering Fuzhou University Fuzhou Fujian China
| | - Yuying Zheng
- College of Materials Science and Engineering Fuzhou University Fuzhou Fujian China
| | - Que Chen
- Fujian Aton New Material Technology Co., Ltd Fuzhou Fujian China
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Effect of alcohols-regulated crystallization on foaming process and cell morphology of polypropylene. J Supercrit Fluids 2021. [DOI: 10.1016/j.supflu.2021.105271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Using P(Pressure)-T(Temperature) Path to Control the Foaming Cell Sizes in Microcellular Injection Molding Process. Polymers (Basel) 2021; 13:polym13111843. [PMID: 34199459 PMCID: PMC8199600 DOI: 10.3390/polym13111843] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/29/2021] [Accepted: 05/30/2021] [Indexed: 11/17/2022] Open
Abstract
Microcellular injection molding technology (MuCell) using supercritical fluid (SCF) as a foaming agent is one of the important green molding solutions for reducing the part weight, saving cycle time, and molding energy, and improving dimensional stability. In view of the environmental issues, the successful application of MuCell is becoming increasingly important. However, the molding process encounters difficulties including the sliver flow marks on the surface and unstable mechanical properties that are caused by the uneven foaming cell sizes within the part. In our previous studies, gas counter-pressure combined with dynamic molding temperature control was observed to be an effective and promising way of improving product quality. In this study, we extend this concept by incorporating additional parameters, such as gas pressure holding time and release time, and taking the mold cooling speed into account to form a P(pressure)-T(temperature) path in the SCF PT diagram. This study demonstrates the successful control of foaming cell size and uniformity in size distribution in microcellular injection molding of polystyrene (PS). A preliminary study in the molding of elastomer thermoplastic polyurethanes (TPU) using the P-T path also shows promising results.
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Zhang X, Wang X, Dong B, Zheng G, Chen J, Shen C, Park CB. Synergetic effect of crystal nucleating agent and melt self-enhancement of isotactic polypropylene on its rheological and microcellular foaming properties. J CELL PLAST 2020. [DOI: 10.1177/0021955x20969553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Crystal nucleating agent Bis (3, 4- dimethylbenzylidene) sorbitol (DMDBS) was used to tune the melt strength and microcellular foaming properties of isotactic polypropylene (iPP) in this study. Rheological testing results reveal that the introduction of DMDBS could enhance the storage modulus and complex viscosity of iPP, obviously increase its crystallization onset temperature, compared to its counterparts without DMDBS. The addition of DMDBS could also significantly increase the cell nucleating ability of iPP, due to its large surface, cooperating with a thermal history control treatment. Quite fine microcellular iPP/DMDBS foams were fabricated with relatively small average cell sizes of nano to several micrometers, and cell densities up to 1011∼1012 cells/cm3, using the synergy effect of DMDBS and iPP’s melt self-enhancement. Under a comparatively low re-saturation pressure of 8 to 12 MPa, ideal microcellular foams could be generated, at a temperature zone of 158 to 162°C, which is slightly below to iPP’s original pellets nominal melting point.
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Affiliation(s)
- Xiaoli Zhang
- School of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology
| | - Xihuan Wang
- School of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology
| | - Binbin Dong
- Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Guoqiang Zheng
- School of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology
| | - Jingbo Chen
- School of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology
| | - Changyu Shen
- School of Materials Science and Engineering, National Engineering Research Center for Advanced Polymer Processing Technology
| | - Chul B Park
- Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
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Weingart N, Raps D, Lu M, Endner L, Altstädt V. Comparison of the Foamability of Linear and Long-Chain Branched Polypropylene-The Legend of Strain-Hardening as a Requirement for Good Foamability. Polymers (Basel) 2020; 12:polym12030725. [PMID: 32213998 PMCID: PMC7183088 DOI: 10.3390/polym12030725] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/19/2020] [Accepted: 03/21/2020] [Indexed: 11/17/2022] Open
Abstract
Polypropylene (PP) is an outstanding material for polymeric foams due to its favorable mechanical and chemical properties. However, its low melt strength and fast crystallization result in unfavorable foaming properties. Long-chain branching of PP is regarded as a game changer in foaming due to the introduction of strain hardening, which stabilizes the foam morphology. In this work, a thorough characterization with respect to rheology and crystallization characteristics of a linear PP, a PP/PE-block co-polymer, and a long-chain branched PP are conducted. Using these results, the processing window in foam-extrusion trials with CO2 and finally the foam properties are explained. Although only LCB-PP exhibits strain hardening, it neither provide the broadest foaming window nor the best foam quality. Therefore, multiwave experiments were conducted to study the gelation due to crystallization and its influence on foaming. Here, linear PP exhibited a gel-like behavior over a broad time frame, whereas the other two froze quickly. Thus, apart from strain hardening, the crystallization behavior/crystallization kinetics is of utmost importance for foaming in terms of a broad processing window, low-density, and good morphology. Therefore, the question arises, whether strain hardening is really essential for low density foams with a good cellular morphology.
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Affiliation(s)
- Nick Weingart
- Department of Polymer Engineering, University of Bayreuth, 95447 Bayreuth, Germany; (N.W.); (D.R.); (L.E.)
| | - Daniel Raps
- Department of Polymer Engineering, University of Bayreuth, 95447 Bayreuth, Germany; (N.W.); (D.R.); (L.E.)
| | - Mingfu Lu
- SINOPEC Beijing Research Institute of Chemical Industry, Beijing, 100013, China;
| | - Lukas Endner
- Department of Polymer Engineering, University of Bayreuth, 95447 Bayreuth, Germany; (N.W.); (D.R.); (L.E.)
| | - Volker Altstädt
- Department of Polymer Engineering, University of Bayreuth, 95447 Bayreuth, Germany; (N.W.); (D.R.); (L.E.)
- Correspondence: ; Tel.: +49-921-557471
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Han S, Jiang C, Yu K, Mi J, Chen S, Wang X. Influence of crystallization on microcellular foaming behavior of polyamide 6 in a supercritical CO
2
‐assisted route. J Appl Polym Sci 2020. [DOI: 10.1002/app.49183] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Shuo Han
- School of Materials and Mechanical EngineeringBeijing Technology and Business University Beijing People's Republic of China
- Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing People's Republic of China
| | - Can Jiang
- School of Materials and Mechanical EngineeringBeijing Technology and Business University Beijing People's Republic of China
- Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing People's Republic of China
| | - Kesong Yu
- School of Materials and Mechanical EngineeringBeijing Technology and Business University Beijing People's Republic of China
- Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing People's Republic of China
| | - Jianguo Mi
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical Technology Beijing People's Republic of China
| | - Shihong Chen
- School of Materials and Mechanical EngineeringBeijing Technology and Business University Beijing People's Republic of China
- Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing People's Republic of China
| | - Xiangdong Wang
- School of Materials and Mechanical EngineeringBeijing Technology and Business University Beijing People's Republic of China
- Beijing Key Laboratory of Quality Evaluation Technology for Hygiene and Safety of Plastics Beijing People's Republic of China
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Modification of iPP microcellular foaming behavior by thermal history control and nucleating agent at compressed CO2. J Supercrit Fluids 2018. [DOI: 10.1016/j.supflu.2017.11.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Chen SC, Hsu PS, Hwang SS. The effects of gas counter pressure and mold temperature variation on the surface quality and morphology of the microcellular polystyrene foams. J Appl Polym Sci 2012. [DOI: 10.1002/app.37994] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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10
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Xin C, He Y, Li Q, Huang Y, Yan B, Wang X. Crystallization behavior and foaming properties of polypropylene containing ultra-high molecular weight polyethylene under supercritical carbondioxide. J Appl Polym Sci 2010. [DOI: 10.1002/app.30717] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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11
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Dong L, Huang J, Li R, Zhang Y, Pan M, Xiong C. N2-filled hollow glass beads as novel gas carriers for microcellular polyethylene. J Appl Polym Sci 2009. [DOI: 10.1002/app.31013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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