Nanocellular polymer foams nucleated by core-shell nanoparticles

Liu, Shanqiu; Zoetebier, Bram; Hulsman, Lars; Zhang, Yuanyuan; Duvigneau, Joost; Vancso, Gyula J.

doi:10.1016/j.polymer.2016.09.016

Cited by 25 publications

(33 citation statements)

References 45 publications

(49 reference statements)

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“…The nucleation efficiency is defined as the ratio of the number of cells per cm 3 unfoamed material to the number of nanoparticles per cm 3 added to the polymer before foaming. 13 , 35 In addition, we recently reported the synthesis of PDMS-grafted silica nanoparticles with a core diameter of 80 nm as highly efficient cell nucleation agents in CO 2 -blown batch foaming of polystyrene and poly(methyl methacrylate) films. 13 Nucleation efficiencies of up to ∼0.5 (i.e., 1 foam cell per 2 particles on average) were achieved for the foaming conditions we reported.…”

Section: Introductionmentioning

confidence: 99%

“… 13 , 35 In addition, we recently reported the synthesis of PDMS-grafted silica nanoparticles with a core diameter of 80 nm as highly efficient cell nucleation agents in CO 2 -blown batch foaming of polystyrene and poly(methyl methacrylate) films. 13 Nucleation efficiencies of up to ∼0.5 (i.e., 1 foam cell per 2 particles on average) were achieved for the foaming conditions we reported. This is the highest nucleation efficiency value observed so far for nanoparticles used as heterogeneous nucleation agents.…”

Section: Introductionmentioning

confidence: 99%

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Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Liu

Eijkelenkamp

Duvigneau

et al. 2017

ACS Appl. Mater. Interfaces

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Core–shell nanoparticles consisting of silica as core and surface-grafted poly(dimethylsiloxane) (PDMS) as shell with different diameters were prepared and used as heterogeneous nucleation agents to obtain CO2-blown poly(methyl methacrylate) (PMMA) nanocomposite foams. PDMS was selected as the shell material as it possesses a low surface energy and high CO2-philicity. The successful synthesis of core–shell nanoparticles was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The cell size and cell density of the PMMA micro- and nanocellular materials were determined by scanning electron microscopy. The cell nucleation efficiency using core–shell nanoparticles was significantly enhanced when compared to that of unmodified silica. The highest nucleation efficiency observed had a value of ∼0.5 for nanoparticles with a core diameter of 80 nm. The particle size dependence of cell nucleation efficiency is discussed taking into account line tension effects. Complete engulfment by the polymer matrix of particles with a core diameter below 40 nm at the cell wall interface was observed corresponding to line tension values of approximately 0.42 nN. This line tension significantly increases the energy barrier of heterogeneous nucleation and thus reduces the nucleation efficiency. The increase of the CO2 saturation pressure to 300 bar prior to batch foaming resulted in an increased line tension length. We observed a decrease of the heterogeneous nucleation efficiency for foaming after saturation with CO2 at 300 bar, which we attribute to homogenous nucleation becoming more favorable at the expense of heterogeneous nucleation in this case. Overall, it is shown that the contribution of line tension to the free energy barrier of heterogeneous foam cell nucleation must be considered to understand foaming of viscoelastic materials. This finding emphasizes the need for new strategies including the use of designer nucleating particles to enhance the foam cell nucleation efficiency.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Liu

Eijkelenkamp

Duvigneau

et al. 2017

ACS Appl. Mater. Interfaces

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“…For example, high-quality foams that have bubble sizes on the order of nanometers exhibit better properties than conventional polymeric foams. 11 However, the creation of high-quality foams is still a challenging task, which is partially attributed to the dependence of the cellular structure on the processing technique used to fabricate the foam. Furthermore, evaluation of a foamed structure that is formed during a real process is also more complex than the foams formed under desired conditions, since the bubble morphology is possibly influenced by the flow-induced effects of dynamic processing conditions.…”

Section: Introductionmentioning

confidence: 99%

Combining foam injection molding with batch foaming to improve cell density and control cellular orientation via multiple gas dissolution and desorption processes

Zhou

Chen

2020

Polymers for Advanced Techs

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In contrast to solid parts fabricated through conventional injection molding (CIM), foamed parts manufactured via foam injection molding (FIM) exhibit substantial variations in mechanical properties, which are attributed to differences in the cellular structure. In this study, parts with different cellular structures are fabricated via FIM, during which the gas dissolution and desorption processes are controlled by subjecting the gas‐laden melt to reciprocating compression and expansion operations. The results suggest that the cell density can be drastically improved by rapidly decreasing the pressure caused by the mold opening and that the cell orientation obviously occurs in the direction perpendicular to the mold‐opening direction. Moreover, the cell density and cellular orientation can be adjusted by utilizing appropriate mold opening and closing operations, leading to improvements in the resultant ultimate mechanical properties. In particular, the foamed samples fabricated with controlled mold opening‐closing operations exhibit excellent tensile strength and strain‐at‐break, indicating that samples containing a high density of cells oriented along the tensile test direction facilitate the formation of superductility and an increase in tensile strength. Hence, a method that combines FIM with batch foaming has been proposed for improving the cellular structure and controlling the cellular orientation.

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“…First, CNTs are excellent heterogeneous nucleating agent to increase the cell density. Cell nucleation is more likely to occur at the interfaces between fillers and polymer matrix because of the relatively low free energy barrier for heterogeneous nucleation . Due to their high aspect ratio and specific area, uniformly dispersed CNTs can offer much more interfaces as the heterogeneous nucleation sites than many other spherical (i.e., nano SiO 2 ) or lamellar fillers (i.e., nano clay).…”

Section: Introductionmentioning

confidence: 99%

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming

Zhao

Wang

et al. 2019

Macro Materials & Eng

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Poly(methyl methacrylate) (PMMA) foams exhibit many advantages over the most popular polystyrene (PS) foams, which make them an ideal candidate for thermal insulation application. First, PMMA has lower carbon content, lower burning rate, smaller heat release rate, and lower smoke emission than PS. [7] So, PMMA foams need less flame retardants than PS foams when used as construction thermal insulation materials, which helps reduce the overall production costs and mitigate the greenhouse effect. Second, PMMA can strongly absorb infrared light in the wavelength range of 2.8-25 µm, [8] while PS can hardly absorb infrared light. Thus, the low-density PMMA foams are expected to block more thermal radiations than the PS foams with the same density. Third, PMMA has higher CO 2 solubility than PS because the carbonyl group in PMMA has stronger adsorption capacity for CO 2 than the benzene ring in PS. [9] The higher CO 2 solubility makes it much easier to prepare low-density PMMA foam, enhancing foam's thermal insulation. Carbon nanotubes (CNTs) with unique electrical, mechanical, and thermal properties have exhibited great value in designing electrical conductive composites, [10,11] electromagnetic interference shielding, [12,13] and energy harvesting materials. [14] These excellent properties of CNTs also make them ideal fillers to design polymer foams for some important reasons. First, CNTs are excellent heterogeneous nucleating agent to increase the cell density. Cell nucleation is more likely to occur at the interfaces between fillers and polymer matrix because of the relatively low free energy barrier for heterogeneous nucleation. [15][16][17] Due to their high aspect ratio and specific area, uniformly dispersed CNTs can offer much more interfaces as the heterogeneous nucleation sites than many other spherical (i.e., nano SiO 2 [18] ) or lamellar fillers (i.e., nano clay [19] ). Moreover, CNTs can endow the polymer foams with multifunctionality by offering the same advantages that they offer in the bulk while not decreasing foam's other properties. For example, CNTs are one kind of good wave-absorbing material that can be recognized as black bodies. In electromagnetic fields, CNTs can attenuate electromagnetic radiation by forming a conductive network (conductivity loss), [12,20] or by the polarization of CNT/polymer interfaces (dielectric loss), [21,22] or by scattering and multiple Polymer Nanocomposite Foaming behavior of poly(methyl methacrylate) (PMMA)/multi-walled carbon nanotubes (MWCNTs) nanocomposites and thermally-insulating, electrical, and mechanical properties of the nanocomposite foams are investigated. PMMA/MWCNT nanocomposites containing various amounts of MWCNTs are first prepared by combining solution and melt blending methods, and then foamed using CO 2 . The foaming temperature and MWCNT content are varied for regulating the structure of PMMA/MWCNT nanocomposite foams. The electrical conductivity measurement results show that MWCNTs have little effect on the electrical conductivity of foams with l...

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Nanocellular polymer foams nucleated by core-shell nanoparticles

Cited by 25 publications

References 45 publications

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Combining foam injection molding with batch foaming to improve cell density and control cellular orientation via multiple gas dissolution and desorption processes

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming

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Nanocellular polymer foams nucleated by core-shell nanoparticles

Cited by 25 publications

References 45 publications

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Silica-Assisted Nucleation of Polymer Foam Cells with Nanoscopic Dimensions: Impact of Particle Size, Line Tension, and Surface Functionality

Combining foam injection molding with batch foaming to improve cell density and control cellular orientation via multiple gas dissolution and desorption processes

Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO2 Foaming

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Thermal‐Insulation, Electrical, and Mechanical Properties of Highly‐Expanded PMMA/MWCNT Nanocomposite Foams Fabricated by Supercritical CO₂ Foaming