Solvent‐Free Generation of Foamed Microcapillary Films with a Dual Network of Interconnected Pores and Internal Channels

Zhao, Jiajun; Xu, Zhongbin; Zheng, Shuilin; Tong, Baohong; Liu, J.; Pei, Hao

doi:10.1002/mame.201900768

Cited by 11 publications

(7 citation statements)

References 41 publications

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“…In this study, the highest VER (34.5) and OC content (94.9%) were achieved with the PBT/TGIC0.2 sample foamed at 194 °C and 20 MPa. The OC content of the PBT/TGIC0.2 foam is higher than those reported for other polymer foams such as PLA foam, [ 12,15,43–45 ] PP‐based foam, [ 10,46,47 ] and PCL foam. [ 48 ] Unfortunately, we could not find reports on the preparation of reticulated/OC foams from engineering materials for comparison.…”

Section: Resultsmentioning

confidence: 67%

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

et al. 2022

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Compared with thermosetting open-cell (OC) foams, thermoplastic OC foams are more useful for saving fossil resources and protecting the environment. Reticulated foams are special types of OC foams that present a 3D net structure with no cell wall between neighboring cells. [1] The foam network is composed of strand-like structures, which are referred to as struts. In contrast, OC foams have a connected cell structure with a broken cell wall between neighboring cells. Owing to their special structure, reticulated foams with low density (<0.1 g cm À3 ) are widely applied in cushioning, environmental protection, [2][3][4] and tissue engineering. [5][6][7] As a type of an engineering thermoplastic material, polybutylene terephthalate (PBT) has excellent properties, such as high mechanical strength and toughness, hightemperature dimensional stability, and chemical resistance, [8,9] which render it a material suitable for preparing reticulated foams under extreme environments. Unfortunately, there are no reports on the preparation of reticulated/OC foams of engineering materials such as PBT. In fact, several important factors should be considered in the preparation of reticulated foams. [1] The first one is to ensure that cells can grow to a certain size. The second is to induce the cell wall to rupture before the cell size becomes excessively large, so as to prevent the destruction of struts owing to the excessive growth of cells, resulting in the collapse of the foam. The third is to prevent an excessively high melt strength to restrict the cell growth and opening. The fabrication of PBT reticulated foams is challenging because of these factors.Unlike thermosetting reticulated foams, thermoplastic reticulated foams have been rarely studied. Park and co-workers [1,10] prepared polypropylene (PP) foams by introducing polytetrafluoroethylene (PTFE) fibers during a continuous extrusion process. The PTFE fibers used as a CO 2 -philic agent adsorbed CO 2 , leading to local plasticization of certain domains, which acted as weak sites during the foaming process. At the same time, the PTFE fibers induced the formation of crystalline heterogeneities, which served as hard sites in the soft matrix to create OCs. Li et al. [11,12] included poly(butylene succinate) in poly(lactic acid) (PLA) to serve as soft weak sites for inducing the opening of the cell structure during the cell growth. Lee [13] introduced polyethylene (PE) with different crystallization temperatures into PP to form a soft/hard heterostructure; the PE domains served as weak sites that ruptured or debonded from PP during cell growth. Plasticizing the matrix using a blowing agent is another strategy for inducing the breakage of the cell wall during cell growth. [14] In addition, a cooling batch foaming method, which could broaden the foaming window for obtaining OC foam, was

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Section: Resultsmentioning

confidence: 67%

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

et al. 2022

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“…Due to its solvent-free process and biodegradability, these foamed MCFs may find wide applications in tissue engineering. [17] Huang et al applied MCFs into droplet microfluidics and had produced emulsions by step-emulsification and multilayered droplets by electrocoalescence. [18,19] Apart from microfluidic applications, Gill et al used MCFs to quantify the extent of micromixing and performed continuous flow chemical reactions based on experiments and numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Precise Control of Microcapillary Size in Microcapillary Films by Liquid‐Assisted Extrusion

Liu

Zheng

et al. 2022

Macro Materials & Eng

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Microcapillary films (MCFs) are plastic films with an array of microcapillaries, which have been widely applied in microfluidics and bioanalytical techniques. However, the precise control of microcapillary size is still a problem hindering the industrial applications of MCFs because the high size uniformity of microcapillaries ensures the production of homogeneous droplets and the robust performance of immunoassays. Here, a novel approach is provided to precisely adjust the size of microcapillaries by liquid‐assisted extrusion and to investigate the combined effects of extrusion, drawing and liquid injection on the microcapillary size. Compared with gas‐assisted extrusion, the size uniformity is improved by at least 5% for 89% experiments and 10% for 42% experiments. Therefore, this method facilitates MCFs’ applications in droplet microfluidics and biotechnologies.

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“…[17] This contradiction makes it difficult to prepare high-expansion PLA open-cell foam. [20][21][22][23] For the preparation of high-expansion PLA foam, many studies have been carried out on the foaming process and material modification. According to the temperature strategy used, the foaming process of PLA can be divided into "heating foaming" and "cooling foaming".…”

Section: Introductionmentioning

confidence: 99%

“…[ 17 ] This contradiction makes it difficult to prepare high‐expansion PLA open‐cell foam. [ 20–23 ]…”

Section: Introductionmentioning

confidence: 99%

Super High‐Expansion Poly(Lactic Acid) Foams with Excellent Oil‐Adsorption and Thermal‐Insulation Properties Fabricated by Supercritical CO₂ Foaming

Zhao

Wang

et al. 2021

Advanced Sustainable Systems

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current materials are mostly traditional petroleum-based polymers. [5,6] This will consume petrochemical resources and produce massive hardly degradable waste. [7] Second, toxic organic solvents or flammable foaming agents are widely used in the current preparation processes. [2,3] In addition, the relationship between the foam structure and the oil-adsorption and thermal-insulation performance is still unclear, thus limiting the development of high-performance foams.Poly(lactic acid) (PLA) is one of the biobased and biodegradable polymers with the most potential to replace traditional petroleum-based polymers. [8] Microcellular foaming is a green and safe technology in which supercritical CO 2 or N 2 is used as the physical foaming agent. [9] Therefore, it is an eco-friendly solution to use the microcellular foaming technology to prepare PLA foams for oil-adsorption and thermal-insulation application. Highperformance oil-adsorption materials should have high expansion ratio and open-cell structure, [10] and thermal-insulation materials generally require high expansion ratio and closed-cell structure. [11] However, the preparation of PLA foam with high expansion ratio is still very challenging. [12] The factors affecting the expansion ratio are very complex and can be divided into material structure and process parameters. The material structure mainly includes chain structure, crystalline structure, blend phase structure, etc. [12,13] And the process parameters mainly contain temperature, gas pressure, depressurization rate, etc. [12,14] These factors will affect the gas concentration, polymer viscoelasticity, heterogeneous nucleation, etc.; and then act on the cell nucleation, cell growth and cell stabilization; and finally influence the expansion ratio. [9,12,14] Specially, the PLA is a semi-crystalline polymer with low melt strength and complicated relationship between crystallization and foaming. First, CO 2 can reduce the crystallization and melting temperature of PLA, [9] and change its crystal morphology. [15,16] Meanwhile, crystals in turn can hinder the dissolution of CO 2 in the PLA. [17,18] Second, excessive crystallization will severely limit the cell growth, and ultimately lead to low expansion ratio and non-uniform cell morphology. [17][18][19] Third, the linear PLA generally possesses poor melt strength, which easily leads to cell collapse and gas loss, thereby restricting continuous foam expansion. [12] Fourth, the requirements of high expansion and Bio-based and biodegradable poly(lactic acid) (PLA) foams with a high expansion ratio show great application potential in oil-adsorption and thermal-insulation, which are crucial for oil-spill cleanup and energy saving. However, it is difficult to prepare high-expansion PLA foam due to the poor melt strength and complex crystallization behavior of PLA. Herein, super high-expansion PLA foams with excellent oil-adsorption and thermal-insulation properties are successfully prepared using a modified supercritical CO 2 foaming technology without introducin...

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Solvent‐Free Generation of Foamed Microcapillary Films with a Dual Network of Interconnected Pores and Internal Channels

Cited by 11 publications

References 41 publications

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

Precise Control of Microcapillary Size in Microcapillary Films by Liquid‐Assisted Extrusion

Super High‐Expansion Poly(Lactic Acid) Foams with Excellent Oil‐Adsorption and Thermal‐Insulation Properties Fabricated by Supercritical CO₂ Foaming

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Solvent‐Free Generation of Foamed Microcapillary Films with a Dual Network of Interconnected Pores and Internal Channels

Cited by 11 publications

References 41 publications

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO2

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO2

Precise Control of Microcapillary Size in Microcapillary Films by Liquid‐Assisted Extrusion

Super High‐Expansion Poly(Lactic Acid) Foams with Excellent Oil‐Adsorption and Thermal‐Insulation Properties Fabricated by Supercritical CO2 Foaming

Contact Info

Product

Resources

About

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

Morphological Evolution from Open Cells to Reticulated Structures in Moderately Branched Polybutylene Terephthalate Foamed Using Supercritical CO₂

Super High‐Expansion Poly(Lactic Acid) Foams with Excellent Oil‐Adsorption and Thermal‐Insulation Properties Fabricated by Supercritical CO₂ Foaming