Low-density PMMA/MAM nanocellular polymers using low MAM contents: Production and characterization

Bernardo, Victoria; León, Judith Martín‐de; Pinto, Javier; Catelani, Tiziano; Athanassiou, Athanassia; Rodríguez‐Pérez, Miguel Ángel

doi:10.1016/j.polymer.2018.12.057

Cited by 30 publications

(43 citation statements)

References 40 publications

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“…PMMA/MAM being a good model system, a huge collection of experiments on batched-foamed PMMA/MAM structured blends was published varying wt% MAM (0.1 to 20 wt%), P saturation , T saturation , ∆P/dt, one-step vs. two-step foaming, T foaming . All works show that density is accessible between 1 and 0.25•10 3 kg•m −3 , mean pore diameter between several tens of micrometers to 0.1 µm, exceptionally down to 50 nm (thanks to hard low temperature saturation conditions) [39,81,89,101,102].…”

Section: Saturation Timementioning

confidence: 99%

Amorphous Polymers’ Foaming and Blends with Organic Foaming-Aid Structured Additives in Supercritical CO2, a Way to Fabricate Porous Polymers from Macro to Nano Porosities in Batch or Continuous Processes

Haurat

Dumon

2020

Molecules

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Organic polymers can be made porous via continuous or discontinuous expansion processes in scCO2. The resulting foams properties are controlled by the interplay of three groups of parameters: (i) Chemical, (ii) physico-chemical, and (iii) technological/process that are explained in this paper. The advantages and drawbacks of continuous (extrusion, injection foaming) or discontinuous (batch foaming) foaming processes in scCO2, will be discussed in this article; especially for micro or nano cellular polymers. Indeed, a challenge is to reduce both specific mass (e.g., ρ < 100 kg·m−3) and cell size (e.g., average pore diameter ϕaveragepores < 100 nm). Then a particular system where small “objects” (coreshells CS, block copolymer MAM) are perfectly dispersed at a micrometric to nanometric scale in poly(methyl methacrylate) (PMMA) will be presented. Such “additives”, considered as foaming aids, are aimed at “regulating” the foaming and lowering the pore size and/or density of PMMA based foams. Differences between these additives will be shown. Finally, in a PMMA/20 wt% MAM blend, via a quasi one-step batch foaming, a “porous to nonporous” transition is observed in thick samples. A lower limit of pore size (around 50 nm) seems to arise.

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Section: Saturation Timementioning

confidence: 99%

Amorphous Polymers’ Foaming and Blends with Organic Foaming-Aid Structured Additives in Supercritical CO2, a Way to Fabricate Porous Polymers from Macro to Nano Porosities in Batch or Continuous Processes

Haurat

Dumon

2020

Molecules

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“…The blend of poly(methyl methacrylate)-poly(butyl acrylate)-poly(methyl methacrylate) (MAM) copolymer with PMMA [33][34][35][36] was proved recently to allow reaching relative densities of 0.23 and cell sizes of 350 nm. [37] Another interesting system is the immiscible blend of PMMA with thermoplastic polyurethane (TPU) that results in a nanostructuration of the TPU phase, as shown by Wang and coworkers. [19] Using a two-step gas dissolution foaming method with an extra cooling step, they obtained a very low-density nanocellular polymer with a relative density as low as 0.125, while the cell size was only 205 nm.…”

Section: Introductionmentioning

confidence: 99%

Nanocellular Polymers with a Gradient Cellular Structure Based on Poly(methyl methacrylate)/Thermoplastic Polyurethane Blends Produced by Gas Dissolution Foaming

Bernardo

León

Sánchez-Calderón

et al. 2019

Macro Materials & Eng

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Graded structures and nanocellular polymers are two examples of advanced cellular morphologies. In this work, a methodology to obtain low‐density graded nanocellular polymers based on poly(methyl methacrylate) (PMMA)/thermoplastic polyurethane (TPU) blends produced by gas dissolution foaming is reported. A systematic study of the effect of the processing condition is presented. Results show that the melt‐blending results in a solid nanostructured material formed by nanometric TPU domains. The PMMA/TPU foamed samples show a gradient cellular structure, with a homogeneous nanocellular core. In the core, the TPU domains act as nucleating sites, enhancing nucleation compared to pure PMMA and allowing the change from a microcellular to a nanocellular structure. Nonetheless, the outer region shows a gradient of cell sizes from nano‐ to micron‐sized cells. This gradient structure is attributed to a non‐constant pressure profile in the samples due to gas desorption before foaming. The nucleation in the PMMA/TPU increases as the saturation pressure increases. Regarding the effect of the foaming conditions, it is proved that it is necessary to have a fine control to avoid degeneration of the cellular materials. Graded nanocellular polymers with relative densities of 0.16–0.30 and cell sizes ranging 310–480 nm (in the nanocellular core) are obtained.

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“…11 Sputter coater SDC 005 of Balzers Union (Liechtenstein). 12 Scanning electron microscope QUANTA 200 FEG of Thermo Fisher Scientific (USA). 13 At least 200 cells were analysed from multiple micrographs per foamed sample.…”

Section: Open Cell Contentmentioning

confidence: 99%

“…Measurements of D at temperatures and pressures typical for solid-state nanofoaming of PMMA by CO2 are available in the literature as follows. Guo and Kumar [28] measured D based on desorption measurements and found that D ranges from 12 2…”

Section: Mass Conservationmentioning

confidence: 99%

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The mechanics of solid-state nanofoaming

et al. 2019

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Solid-state nanofoaming experiments are conducted on two PMMA grades of markedly different molecular weight using CO2 as the blowing agent. The dependence of porosity of the nanofoams upon foaming time and foaming temperature is measured. Also, the microstructure of the PMMA nanofoams is characterized in terms of cell size and cell nucleation density. A one dimensional numerical model is developed to predict the growth of spherical, gas-filled voids during the solid-state foaming process. Diffusion of CO2 within the PMMA matrix is sufficiently rapid for the concentration of CO2 to remain almost uniform spatially. The foaming model makes use of experimentally calibrated constitutive laws for the PMMA grades, and the effect of dissolved CO2 is accounted for by a shift in the glass transition temperature of the PMMA. The observed limit of achievable porosity is interpreted in terms of cell wall tearing;it is deduced that the failure criterion is sensitive to cell wall thickness.

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Low-density PMMA/MAM nanocellular polymers using low MAM contents: Production and characterization

Abstract: Low-density nanocellular polymers based on PMMA/MAM blends are produced. • Low MAM copolymer contents, as low as 0.1 wt%, are used to produce such materials. • The physical mechanisms that allow this reduction of the density are discussed.

Cited by 30 publications

References 40 publications

Amorphous Polymers’ Foaming and Blends with Organic Foaming-Aid Structured Additives in Supercritical CO2, a Way to Fabricate Porous Polymers from Macro to Nano Porosities in Batch or Continuous Processes

Amorphous Polymers’ Foaming and Blends with Organic Foaming-Aid Structured Additives in Supercritical CO2, a Way to Fabricate Porous Polymers from Macro to Nano Porosities in Batch or Continuous Processes

Nanocellular Polymers with a Gradient Cellular Structure Based on Poly(methyl methacrylate)/Thermoplastic Polyurethane Blends Produced by Gas Dissolution Foaming

The mechanics of solid-state nanofoaming

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