Foaming of amorphous polymers and blends in supercritical CO 2 : Solubility versus block copolymers addition

Abstract

Supercritical CO₂ (scCO₂) is used as a medium for foaming amorphous polymers. Astudy of the solubility of supercritical CO₂ in several amorphous polymers (PS andPMMA) and blends is performed, followed by an investigation of the foaming behavior of the polymer–gas systems. Nano-structuring triblock copolymers (styrene-co-butadiene-co-methylmethacrylate SBM and methylmethacrylate-co-butylacrylate-co-methylmethacrylate MAM) were blended as additives to PS or PMMA by extrusion. The addition of these triblock copolymers results in an important weight gain ratio of gas in a wide range of temperatures (from 25 to 80°C), relating this weight gain ratio to the foaming behavior of the blends (CO₂ is preferentially located in the micro or nano-domains issued from the structuration of the block copolymer). Foaming is carried out in a batch one-step scCO₂ process, keeping constant the saturation pressure and depressurization rate (300 bar and 60 bar/min, respectively). Influence of saturation temperature (25–85 °C) on the final porous structure is shown. In spite of the influence of the terpolymer on the weight gain ratio, the structuration is believed to provide a good control of microcellular foams in PS and PMMA.

Keywords

microcellular foaming solubility amorphous polymers block copolymers

Get full access to this article

View all access options for this article.

References

Martini JE, Waldman FA and Suh NP. U.S. Patent, 4 473 665, 1984.

Reverchon

Cardea

. Production of controlled polymeric foams by supercritical CO₂. J Supercrit Fluids. 2007; 40: 144–152.

Yoon

Cha

. Change of glass transition temperature of polymers containing gas. Polym Test. 2001; 20: 287–293.

Park

Pop-Iliev

. Effects of die geometry on cell nucleation of PS foams blown with CO₂. Polym Eng Sci. 2003; 43(7): 1378–1390.

Arora

Lesser

McCarthy

. Preparation and characterization of microcellular polystyrene foams processed in supercritical carbon dioxide. Macromolecules. 1998; 31: 4614–4620.

Jacobs

LJM

Danen

KCH

Kemmere

Keurentjes

JTF

. A parametric study into the morphology of poly(styrene)-co-methyl methacrylate foams using supercritical carbon dioxide as a blowing agent. Polymer. 2007; 48: 3771–3780.

Uosaki

Morokami

Moriyoshi

. Generation of microcellular poly(methyl methacrylate) by compressed gases. High Press Res. 2001; 20: 467–475.

Xin

Wang

. Crystallization behaviour and foaming properties of polypropylene containing ultra-high molecular weight polyethylene under ScCO₂. J Beij Univ Chem Technol. 2002; 36: 38–42.

Zhai

Leung

Wang

Naguib

Park

. Preparation of microcellular poly(ethylene-co-octene) rubber foam with supercritical carbon dioxide. J Appl Polym Sci. 2010; 116: 1994–2004.

10.

Reglero

Dumon

Pinto

Rodríguez-Perez

. Low-density nanocellular foams produced by high-pressure carbon dioxide. Macromol Mater Eng. 2011; 296: 752–759.

11.

Nagui

. Effect of processing parameters on cellular structures and mechanical properties of PMMA microcellular foams. Cell Polym. 2005; 24: 177–195.

12.

Condo

Sanchez

Panayiotou

Johnston

. Glass transition behavior including retrograde vitrification of polymers with compressed fluid diluents. Macromolecules. 1992; 25: 6119–6127.

13.

Hwang

Cha

. The relationship between gas absorption and the glass transition temperature in a batch microcellular foaming process. Polym Test. 2002; 21: 269–274.

14.

Reglero

Viot

Dumon

. Foaming behaviour and compressive properties of microcellular nanostructured polystyrene. Cell Polym 2009; 28. (6): 363–386.

15.

Reglero

Tallon

Pedros

Dumon

. Two-step micro cellular foaming of amorphous polymers in supercritical CO₂. J Supercrit Fluids. 2011; 57: 87–94.

16.

Gendron

Champagne

Delaviz

Polasky

. Foaming polystyrene with a mixture of CO2 and ethanol. J Cell Plast. 2006; 42: 127–138.