Synthesis of polystyrene/bentonite clay nanocomposites by emulsion polymerization in aqueous and in supercritical carbon dioxide medium

2011 ◽  
Vol 45 (23) ◽  
pp. 2437-2446 ◽  
Author(s):  
I.R. Kamrupi ◽  
S.K. Dolui
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Emulsion Polymerization ◽  
Bentonite Clay ◽  
Gel Permeation Chromatography ◽  
Clay Nanocomposites ◽  
Sodium Dodecylbenzene Sulfonate ◽  
Transmission Electron ◽  
Supercritical Carbon

In this article, the synthesis of polystyrene/bentonite clay nanocomposites by emulsion polymerization in aqueous and supercritical carbon dioxide (sc-CO2) media using organically modified bentonite clay is reported. The modified clay is dispersed within the monomer via ultrasonication and the mixture is allowed to undergo in situ emulsion polymerization, resulting in the formation of polymer/clay nanocomposites. A comparative study of the properties of the nanocomposites synthesized in the two media was carried out. The effects of clay concentration on polymer conversion, molecular weight, morphology, and mechanical properties have been investigated. Sodium dodecylbenzene sulfonate was used as a stabilizer in aqueous medium and polydimethylsiloxane in sc-CO2 medium. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, gel permeation chromatography, and thermogravimetric analysis.

scholarly journals Potato starch nanocrystal preparation via supercritical carbon dioxide pretreatment combined with enzymatic hydrolysis

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7671-7683
Author(s):  
Hervé M. Nlandu ◽  
Nasima Chorfa ◽  
Khaled Bekacemi ◽  
Safia Hamoudi
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Enzymatic Hydrolysis ◽  
Supercritical Carbon Dioxide ◽  
Potato Starch ◽  
X Ray ◽  
Transmission Electron ◽  
Starch Nanoparticles ◽  
Microscopy Images ◽  
Supercritical Carbon

In this work, starch nanocrystals were successfully produced from downgraded potatoes using enzymatic hydrolysis combined with a supercritical carbon dioxide pretreatment to improve the accessibility of the enzyme to the starches. Enzymatic hydrolysis was carried out using the pullulanase enzyme at a temperature of 60 °C and a pH of 4. Following hydrolysis, the starch nanoparticles were recovered via precipitation and recrystallization. Comparative characterization of the native, supercritical carbon dioxide-pretreated, and hydrolyzed-recrystallized starch materials was conducted via transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The scanning electron microscopy images revealed alterations, e.g., layered strips, on the surface of the potato starch granules after the supercritical carbon dioxide pretreatment. The transmission electron microscopy images revealed that spherical nanostructures from 80 nm to 150 nm were successfully produced. The Fourier transform infrared spectroscopy spectra displayed several absorption bands corresponding to the molecular structure of starches. The X-ray diffractograms exhibited a typical B-type scattering pattern for all the samples. In addition, it was found that the crystallinity of the potato starch nanoparticles was considerably increased compared with native starch.

Microcellular Foaming of Polypropylene/Clay Nanocomposites with Supercritical Carbon Dioxide

2009 ◽  
Vol 45 (6) ◽  
pp. 515-538 ◽  
Author(s):  
Xiu-Lei Jiang ◽  
Jin-Biao Bao ◽  
Tao Liu ◽  
Ling Zhao ◽  
Zhi-Mei Xu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Clay Nanocomposites ◽  
Microcellular Foaming ◽  
Supercritical Carbon

Synthesis of polylactide/clay nanocomposites by in situ intercalative polymerization in supercritical carbon dioxide

2009 ◽  
Vol 45 (3) ◽  
pp. 643-648 ◽  
Author(s):  
Laetitia Urbanczyk ◽  
Fred Ngoundjo ◽  
Michael Alexandre ◽  
Christine Jérôme ◽  
Christophe Detrembleur ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Clay Nanocomposites ◽  
Intercalative Polymerization ◽  
Supercritical Carbon

Supercritical Carbon Dioxide-Processed Dispersed Polystyrene−Clay Nanocomposites

2008 ◽  
Vol 41 (21) ◽  
pp. 8038-8046 ◽  
Author(s):  
Mihai Manitiu ◽  
Robert J. Bellair ◽  
Steven Horsch ◽  
Esin Gulari ◽  
Rangaramanujam M. Kannan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Clay Nanocomposites ◽  
Supercritical Carbon
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