Multi-Stage Recycling Induced Morphological Transformations in Solid-State Microcellular Foaming of Polystyrene

Singh, Indrajeet; Gandhi, Abhishek; Biswal, Manoranjan; Mohanty, Smita; Nayak, Sanjay K.

doi:10.1177/026248931803700302

Cited by 10 publications

(8 citation statements)

References 58 publications

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“…Several works claim that anisotropic cellular structures can be a result of a preferable growth of the cells in a certain direction. To evaluate if this was the reason underlying the anisotropy observed in the materials of the present work, the expansion ratios in different directions of the cellular materials were measured.…”

Section: Resultsmentioning

confidence: 99%

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Bernardo

León

Rodríguez‐Pérez

2019

Polymer International

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This work presents a new strategy for obtaining nanocellular materials with high anisotropy ratios by means of the addition of needle-like nanoparticles. Nanocellular polymers are of great interest due to their outstanding properties, whereas anisotropic structures allow the realization of improved thermal and mechanical properties in certain directions. Nanocomposites based on poly(methyl methacrylate) (PMMA) with nanometric sepiolites are generated by extrusion. From the extruded filaments, cellular materials are produced using a two-step gas dissolution foaming method. The effect of adding various types and contents of sepiolites is investigated. As a result of the extrusion process, the needle-like sepiolites are aligned in the machine direction in the solid nanocomposites. Regarding the cellular materials, the addition of sepiolites allows one to obtain anisotropic nanocellular polymers with cell sizes of 150 to 420 nm and cell nucleation densities of 10 13 -10 14 nuclei cm −3 and presenting anisotropy ratios ranging from 1.38 to 2.15, the extrusion direction being the direction of the anisotropy. To explain the appearance of anisotropy, a mechanism based on cell coalescence is proposed and discussed. In addition, it is shown that it is possible to control the anisotropy ratio of the PMMA/sepiolite nanocellular polymers by changing the amount of well-dispersed sepiolites in the solid nanocomposites.

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Section: Resultsmentioning

confidence: 99%

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Bernardo

León

Rodríguez‐Pérez

2019

Polymer International

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“…Gas dissolution foaming process [8] has been used to produce transparent nanocellular PMMA [9]. These foaming tests were carried out in a pressure vessel (model PARR 4760) provided by Parr Instrument Company (Moline, IL, USA) placed inside a freezer that allows reaching temperatures from −15°C to −32°C.…”

Section: Samples Preparationmentioning

confidence: 99%

Transparent nanocellular PMMA: Characterization and modeling of the optical properties

León

Pura

Bernardo

et al. 2019

Polymer

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Transmittance to visible light of transparent nanocellular polymethylmethacrylate was measured. • Samples with a cell size 14 nm and a relative density of 0.46 can present transmittances as high as 0.94. • A theoretical model predicting the transmittance to visible light of nanocellular polymers has been developed. • Rayleigh scattering is main mechanisms of light transmission in transparent nanocellular polymethylmethacrylate.

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“…Microcellular polymers have been implemented at the industrial level thanks to the successful scaling‐up of the production process. Nowadays, large parts of microcellular plastics are produced by means of extrusion or injection molding …”

Section: Introductionmentioning

confidence: 99%

Overcoming the Challenge of Producing Large and Flat Nanocellular Polymers: A Study with PMMA

et al. 2019

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Although nanocellular polymers are interesting materials with improved properties in comparison with conventional or microcellular polymers, the production of large and flat parts of those materials is still challenging. Herein, gas dissolution foaming process is used to produce large and flat nanocellular polymethylmethacrylate samples. In order to do that, the foaming step is performed in a hot press. The methodology is optimized to produce flat samples with dimensions of 100 Â 100 Â 6 mm 3 , relative densities in the range 0.25-0.55 and cell sizes around 250 nm. Additionally, foaming parameters are modified to study their influence on the final cellular structure, and the materials produced in this paper are compared with samples produced by using a most conventional approach in which foaming step is conducted in a thermal bath. Results obtained show that an increment in the foaming temperature leads to a reduction in relative density and an increase of cell nucleation density. Moreover, differences in the final cellular structure for materials produced by both foaming routes are studied, proving that although there exist some differences, the mechanisms governing the nucleation and growing are the same in both processes, leading to the production of homogeneous materials with very similar cellular structures.J. Martín-de Le on, V. Bernardo, P. Cimavilla-Román, Dr. S. P erez-Tamarit, Prof. M. A. Rodríguez-P erez Cellular Materials Laboratory (CellMat) Universidad de Valladolid

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Multi-Stage Recycling Induced Morphological Transformations in Solid-State Microcellular Foaming of Polystyrene

Cited by 10 publications

References 58 publications

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

Transparent nanocellular PMMA: Characterization and modeling of the optical properties

Overcoming the Challenge of Producing Large and Flat Nanocellular Polymers: A Study with PMMA

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