Plasticization of polymers with supercritical carbon dioxide: Experimental determination of glass‐transition temperatures

Alessi, Paolo; Cortesi, Angelo; Kikic, Ireneo; Vecchione, Febe

doi:10.1002/app.11881

Cited by 118 publications

(87 citation statements)

References 12 publications

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“…It is observed that an increase in the saturation pressure leads to a small reduction in the relative density. This trend is a consequence of the plasticization effect of the CO 2 : when the gas diffuses into a polymer, the glass transition temperature drops [49][50][51][52], and the polymer is now characterized by its effective glass transition temperature, T g,eff . The temperature difference between the foaming temperature and the T g,eff determines the relative [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] density obtained, because once the T g,eff reaches the temperature of the thermal bath the polymer is no longer in the rubbery state and has no mobility to grow.…”

Section: Cellular Nanocompositesmentioning

confidence: 99%

PMMA-sepiolite nanocomposites as new promising materials for the production of nanocellular polymers

Bernardo

León

Laguna‐Gutiérrez

et al. 2017

European Polymer Journal

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A B S T R A C TIn this work, a new system based on poly(methyl methacrylate) (PMMA) sepiolite nanocomposites that allow producing nanocellular polymers by using the gas dissolution foaming technique is described. Nanocomposites with different nanoparticle types and contents have been produced by extrusion. From these blends, cellular materials have been fabricated using the so-called gas dissolution foaming method. An extensive study of the effect of the processing parameters (saturation pressure and foaming temperature) on the cellular materials produced has been performed. Results showed that among the three sepiolites used, only those modified with a quaternary ammonium salt are suitable for being used as nucleating agents in PMMA. With these nanoparticles bimodal cellular polymers, with micro and nanometric cells, have been produced. Cell sizes in the range of 300-500 nm and cell densities of the order of 10 13 -10 14 nuclei/cm 3 have been obtained in the nanocellular region. A foaming temperature of 80°C and a wide range of saturation pressures (between 10 and 30 MPa) and low particle contents (between 0.5 and 1.5 wt%) allow obtaining these materials. Furthermore, it has been found that cell size in the nanometric population can be controlled by means of the particles content; a reduction in the cell size is obtained when the particles content increases. Finally, results indicate that an increase in the foaming temperature leads to cellular nanocomposites with lower relative densities (below 0.21) and larger cell sizes (above 450 nm).

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Section: Cellular Nanocompositesmentioning

confidence: 99%

PMMA-sepiolite nanocomposites as new promising materials for the production of nanocellular polymers

Bernardo

León

Laguna‐Gutiérrez

et al. 2017

European Polymer Journal

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“…Usually, scCO 2 plasticizes the polymer and reduces the glass-transition temperature. 15 It is believed that surface plasticization of the core material by scCO 2 facilitates the interaction of carbon with the core materials.…”

Section: ¹1mentioning

confidence: 99%

A Facile and Green Method to Prepare Conductive Carbon-coated Polymer Microspheres Using Supercritical Carbon Dioxide

et al. 2016

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We introduce a facile method to synthesize a new class of coreshell microspheres composed of resin core particles coated with various carbon materials. The coreshell microspheres were prepared by a one-pot process in which carbon materials such as edge-exfoliated graphite and expanded graphite were dispersed together with core substrates like polystyrene and poly(styrene/2-hydroxyethyl methacrylate) spherical particles in supercritical carbon dioxide. The obtained microspheres were characterized by thermogravimetric analysis, Raman spectroscopy, and scanning electron microscopy. The results indicate that the carbon shells are tightly attached to the surface of the core substrates. Furthermore, because of excellent adhesion, the carbon-coated polymer particles exhibited extremely high electrical conductivity with particle resistance of less than 50 ³ cm despite the presence of an insulating polymeric core material.

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“…High-pressure CO 2 is able to plasticise and effectively liquefy many polymers at temperatures below their glass transition temperatures (T g ) and melting points (T m ) [2,16,[18][19][20][21][22][23][24][25][26][27], thereby opening up opportunities for new processes and incorporation of thermally labile molecules [17,28].…”

Section: Introductionmentioning

confidence: 99%

High-pressure rheological analysis of CO2-induced melting point depression and viscosity reduction of poly(ε-caprolactone)

Curia

Focatiis

Howdle

2015

Polymer

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(2015) High-pressure rheological analysis of CO2-induced melting point depression and viscosity reduction of poly(ε-caprolactone). Polymer, Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/45413/1/curia_polymer2015_preprint.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the Creative Commons Attribution Non-commercial No Derivatives licence and may be reused according to the conditions of the licence. For more details see: http://creativecommons.org/licenses/by-nc-nd/2.5/ A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Furthermore, a significant decrease in the viscosity of two PCL grades with different molecular weight (M n~1 0 kDa and 80 kDa) was also detected upon increasing the CO 2 pressure to 300 bar.Experimental viscosity data were fitted to the Carreau model to quantify the extent of the plasticising effects on the zero-shear viscosity and relaxation time under different conditions. Similar analyses were conducted under high-pressure nitrogen, to compare the effects obtained in the presence of a non-plasticising gas.

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Plasticization of polymers with supercritical carbon dioxide: Experimental determination of glass‐transition temperatures

Cited by 118 publications

References 12 publications

PMMA-sepiolite nanocomposites as new promising materials for the production of nanocellular polymers

PMMA-sepiolite nanocomposites as new promising materials for the production of nanocellular polymers

A Facile and Green Method to Prepare Conductive Carbon-coated Polymer Microspheres Using Supercritical Carbon Dioxide

High-pressure rheological analysis of CO2-induced melting point depression and viscosity reduction of poly(ε-caprolactone)

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