Blowing agent free generation of nanoporous poly(methylmethacrylate) materials

Lena, Grassberger; Koch, Karin; Oberhoffer, Roland; Müller, Alexander; Klemmer, Helge F. M.; Strey, R.

doi:10.1007/s00396-017-4012-1

Cited by 5 publications

(3 citation statements)

References 43 publications

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“…It has been proved that the thermal conductivity through the gas phase can be reduced when the cell size moves to the nanoscale. [17][18][19][20] Enhanced mechanical performance was also demonstrated in some nanocellular polymers. [21,22] Further, it is possible to produce semi-transparent nanocellular polymers, [23,24] among other interesting properties and applications.…”

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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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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“…Notario and coworkers [12] measured the thermal conductivity of nanocellular poly(methyl methacrylate) (PMMA) with different cell sizes, proving the strong influence of the cell size in the conductivity (Knudsen effect). Grassberger et al [15] demonstrated the same idea in blowing agent free nanocellular PMMA. In the work of Wang et al [16], a nanocellular polymers based on blends of low-density PMMA and thermoplastic polyurethane (TPU) was shown to present a thermal conductivity as low as 24.8 mW/mK.…”

Section: Introductionmentioning

confidence: 82%

Modeling the heat transfer by conduction of nanocellular polymers with bimodal cellular structures

Bernardo

León

Pinto

et al. 2019

Polymer

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A model to predict the thermal conductivity of nanocellular polymers is presented. • This model applies to nanocellular materials with non-uniform cellular structures. • The thermal conductivity of bimodal systems with nanometric cells is predicted. • The model is validated using experimental results of real bimodal systems. • It can be also applied to nanocellular polymers with wide cell size distributions.

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“…These behaviours can be attributed to the confinement of the polymer in very thin cell walls, an effect that has been confirmed using different techniques such as differential scanning calorimetry (DSC) or Raman spectroscopy [ 15 , 16 ]. In addition, such materials are present very low thermal conductivities due to the so-called Knudsen effect [ 17 , 18 , 19 , 20 ]. According to the Knudsen theory [ 21 ], when the cell size is comparable to the mean free path of the gas molecules inside the pores (around 70 nm), the gas molecules collide more often with the cells walls than with each other, so the energy transfer through the gas is reduced.…”

Section: Introductionmentioning

confidence: 99%

Nanocellular Polymers: The Challenge of Creating Cells in the Nanoscale

2019

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The evolution of technology means that increasingly better materials are needed. It is well known that as a result of their interesting properties, nanocellular polymers perform better than microcellular ones. For this reason, the investigation on nanocellular materials is nowadays a very topical issue. In this paper, the different approaches for the production of these materials in our laboratory are explained, and results obtained by using polymethylmethacrylate (PMMA) are shown. Homogeneous nucleation has been studied by using raw PMMA, while two different systems were used for heterogeneous nucleation; adding nanoparticles to the system and using nanostructured polymers as solid precursors for foaming. The effects of the different parameters of the production process (gas dissolution foaming process) have been evaluated for all systems being possible to establish a comparison between the materials produced by different approaches. Moreover, the limitations and future work to optimise the materials produced are also discussed.

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Blowing agent free generation of nanoporous poly(methylmethacrylate) materials

Cited by 5 publications

References 43 publications

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

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

Modeling the heat transfer by conduction of nanocellular polymers with bimodal cellular structures

Nanocellular Polymers: The Challenge of Creating Cells in the Nanoscale

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