Experimental and numerical analysis of bubble nucleation in foaming polymer

Yang, Jian; Jiang, Tuanhui; Liu, Bujin; Chun, Zhang; Zeng, Xiangbu; He, Li; Gong, Wei

doi:10.1016/j.matdes.2021.109577

Cited by 26 publications

(15 citation statements)

References 37 publications

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“…Hence, the ability of the composite foam to resist deformation is enhanced, and the higher the content, the more effective the effect obviously. Second, the average cell diameter of the composite foam decreases with increasing graphene content, so the deformation occurring when the same compressive stress is resisted becomes smaller 42 . It should be noted that the compressive strength of 5.0 wt% RGO composite foam is less than that of MEG composite foam because the cell shape of the RGO composite foam (Figure 8e) is distorted and is not a perfect spherical structure, so the ability to resist deformation is reduced.…”

Section: Resultsmentioning

confidence: 98%

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

Sima

Sui

Zhang

2022

J of Applied Polymer Sci

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Mechanical exfoliation of graphene (MEG) and reduced graphene oxide (RGO) are fabricated with using graphite and they are used as fillers to improve the electromagnetic interference (EMI) shielding performance and thermal stability of polysiloxane composite foam. Since graphene builds a conductive network in the matrix and at the same time enhances the impedance mismatch between the syntactic foam and the external free space, the total shielding effectiveness (SE total ) of the composite foam can reach up to 4.74 dB, which is 500% higher than that of pure foam. Moreover, the layered structure of graphene can restrict the small molecules generated during the foam pyrolysis process from leaving the system, and also increases the maximum decomposition temperature of the composite foam (increased from 431.8 to about 500 C), which improves the thermal stability of the foam. These results indicate that the combination of graphene in polysiloxane foams produces composite foams with multifunctional properties, suitable for applications requiring EMI shielding and thermal performance.

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Section: Resultsmentioning

confidence: 98%

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

Sima

Sui

Zhang

2022

J of Applied Polymer Sci

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“…The influence of the melt temperature on cell formation mainly lies in two aspects: firstly, formula (1) is a modified form of the logistic model to describe the relationship between cell number n and time t [ 29 ]. Through the establishment of the mathematical model, the Gibbs free energy Δ G at different temperatures can be fitted ( Table 3 ).…”

Section: Resultsmentioning

confidence: 99%

“…The matrix PP and foaming agent masterbatch were evenly mixed in a certain proportion and added into the cavity volume controllable foaming injection molding machine (TTI-205Ge, Donghua Machinery Co., Ltd., Dongguan, China). The device diagram is shown in Figure 2 [ 29 ]. PP foaming materials were prepared by the core-back injection process and the short-shot injection process.…”

Section: Methodsmentioning

confidence: 99%

“…In the stage of cell stabilization, the n value is stable at 200 • C after 18 s, while the stable time is shortened by 6 s at 230 • C, and the final n value increases from 56 to 234. The influence of the melt temperature on cell formation mainly lies in two aspects: firstly, formula (1) is a modified form of the logistic model to describe the relationship between cell number n and time t [29]. Through the establishment of the mathematical model, the Gibbs free energy ΔG at different temperatures can be fitted (Table 3).…”

Section: Effect Of Melt Temperature On Cell Formationmentioning

confidence: 99%

“…Secondly, according to Henry's law and the critical nucleation radius formula [30] (formula (2), formula (3)), the cells will expand spontaneously only when the cell size is larger than the critical nucleation radius (RC) in formula (3); otherwise, the cells will disappear. With the increasing temperature, the melt viscosity decreases (Figure 5b), which will lead to an increase the free volume and the molecular spacing in the polymer The influence of the melt temperature on cell formation mainly lies in two aspects: firstly, formula (1) is a modified form of the logistic model to describe the relationship between cell number n and time t [29]. Through the establishment of the mathematical model, the Gibbs free energy ∆G at different temperatures can be fitted (Table 3).…”

Section: Effect Of Melt Temperature On Cell Formationmentioning

confidence: 99%

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In-Situ Visualization of the Cell Formation Process of Foamed Polypropylene under Different Foaming Environments

et al. 2021

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In this paper, the dynamic foaming process of micro-foaming polypropylene (PP) in different foaming environments in real time was obtained via a visualization device. The relationship curve between cell number (n) and foaming time (t) was plotted, and then the nucleation kinetics of foam cells was analyzed. Results showed that the formation rate of cells changed obviously with the variation of melt temperature and the content of the foaming agent. The n-t curves presented a typical “S” shape, which indicated that the appearance of the cell number increased slowly in the initial foaming period, then increased rapidly in a short time, and finally maintained a certain value. When a certain pressure was applied to the PP melt, the external force had a great influence on the n-t curve. With the increasing external force, the rate of cell formation increased rapidly, and the shape of the n-t curve changed from “S” to “semi-S” without an obvious slow increase. The investigation of the n-t relationship in the PP dynamic foaming process under different foaming environments could provide effective bases for improving the foaming quality of injection molding foaming materials.

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A facile and efficient strategy for fabrication of silicone rubber foam based on in situ precuring‐supercritical CO₂ foaming technology

Li,

Wei,

et al. 2024

J of Applied Polymer Sci

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In this work, a facile in situ precuring and supercritical CO2 (sc‐CO2) foaming technology is proposed to fabricate silicone rubber foam (SRF) with a tunable cell structure. Uncured silicone rubber is put into the autoclave to saturate sc‐CO2 directly, which not only shorts the saturation time but also accelerates the curing reaction in the precuring process. In the foaming process, cell nucleation is triggered by rapid release of pressure. The cell structure of SRF samples with cell size range of 9.45 to 128.09 μm, cell density range of 3.5 × 105 cells/cm3 to 5.7 × 108 cells/cm3, and porosity range of 28.35% to 77.28% are successfully fabricated by controlling of precuring time, saturation pressure and foaming temperature. To guarantee the dimensional stability and optimize surface quality of SRF samples, in situ post‐curing process is implemented within the foaming mold. With the increase of cell size from 9.91 to 128.09 μm, the compressive stress at strain of 75% decreases from 2.19 to 0.61 MPa, while the energy loss coefficient reduces from 35.4% to 16.9%, exhibiting excellent compression recovery steady. The new technique integrates the precuring, foaming process and post‐curing into an autoclave to simplify the SRF procedure.

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Experimental and numerical analysis of bubble nucleation in foaming polymer

Cited by 26 publications

References 37 publications

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

In-Situ Visualization of the Cell Formation Process of Foamed Polypropylene under Different Foaming Environments

A facile and efficient strategy for fabrication of silicone rubber foam based on in situ precuring‐supercritical CO₂ foaming technology

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Experimental and numerical analysis of bubble nucleation in foaming polymer

Cited by 26 publications

References 37 publications

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

Preparation of polysiloxane foam with graphene for promoting electromagnetic interference shielding performance and thermal stability

In-Situ Visualization of the Cell Formation Process of Foamed Polypropylene under Different Foaming Environments

A facile and efficient strategy for fabrication of silicone rubber foam based on in situ precuring‐supercritical CO2 foaming technology

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Product

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A facile and efficient strategy for fabrication of silicone rubber foam based on in situ precuring‐supercritical CO₂ foaming technology