Foaming of an Immiscible Blend System Using Organic Liquids as Blowing Agents

Abstract

Foaming of blend systems is a promising approach to develop cellular materials with a set of desired properties. However, foaming of blend systems is not only a chance but also a challenge, as different polymers have to be foamed at the same foaming conditions. The best conditions during foaming are individual to each polymer and influence the obtained cellular structure. In immiscible polymer blends like poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) (SAN) the differences in glass-transition temperature (T_g) and viscosity are vast and can inhibit the foaming of the blend system. In order to minimize the above-mentioned difference in T_g and viscosity, one approach is to choose a blowing agent, which shows a selective solubility in one polymer phase, working as a selective plasticizer. The aim of the present study is to evaluate systematically the foaming behavior of immiscible PPE/SAN blend systems using ethanol and n-pentane as blowing agents. Mass uptake of ethanol and n-pentane in the PPE/SAN-blends as function of the blend composition is measured, offering a selective solubility of ethanol in SAN, while n-pentane shows a high affinity to PPE. The plasticizing effect on the blend phases PPE and SAN is theoretically estimated using the Chow-equation and the WLF-equation. After foaming the blowing agent saturated blend samples in an oil-bath at different temperatures, the density reduction and the cellular structures are analyzed and correlated to the blend morphology, the blowing agent solubility in the blend phase, the rheological properties and the glass transition temperature of the nonsaturated and saturated blend phases.

Keywords

blend foam ethanol n-pentane.

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References

Klempner, D. and Frisch, K.C. ( 1991). Handbook of Polymeric Foams and Foam Technology , Munich, Hanser.

Lee, S.T. ( 2000). Foam Extrusion, Boca Raton , CRC Press.

Gendron, R. ( 2005). Thermoplastic Foam Processing. Principles and Development , Boca Raton, CRC Press .

Ruckdäschel, H. , Rausch, J. , Sandler , J.K.W. , Altstädt , V. , Schmalz, H. and Müller, A.H.E. Correlation of the Melt Rheological Properties with the Foaming Behavior of Immiscible Blends of Poly(2,6-dimethyl-1,4-phenylene ether) and Poly(styrene-co-acrylonitrile) , Polym. Eng. Sci. , 2008: 48: 2111-2125.

Taki, K. , Nitta, K. , Kihara, S.I. and Ohshima, M. CO2 Foaming of Poly(ethylene glycol)/Polystyrene Blends: Relationship of the Blend Morphology, CO2 Mass Transfer, and Cellular Structure, J. Appl. Polym. Sci., 2005: 97: 1899-1906.

Göldel, A. , Ruckdäschel , H. , Müller, A.H.E. , Pötschke, P. and Altstädt, V. Controlling the Morphology of Immiscible Poly(2,6-dimethyl-1,4-phenylene ether)/ Poly(styrene-co-acrylonitrile) Blends via Addition of Polystyrene , e-Polymers, 2008: 151: 1-17.

Tol, R.T. , Groeninckx, G. , Vinckier , I. , Moldenaers, P. and Mewis, J. Phase Morphology and Stability of Co-continuous (PPE/PS)/PA6 and PS/PA6 Blends: Effect of Rheology and Reactive Compactibilization , Polymer, 2004: 45: 2587-2601.

Everaert, V. , Aerts, L. and Groeninckx, G. Phase Morphology Development in Immiscible PP/(PS/PPE) Blends Influence of the Melt-viscosity Ratio and Blend Composition, Polymer, 1999 : 40: 6627-6644.

Paul, D.R. and Bucknall, C.B. ( 2000). Polymer Blends. Volume 2: Performance, New York, John Wiley & Sons.

10.

Daigenault, L.E. and Gendron , R. Blends of CO2 and 2-Ethyl Hexanol as Replacement Foaming Agents for Extruded Polystyrene, J. Cell. Plast., 2001: 37: 262-272.

11.

Gendron, R. , Champagne, M.F. , Delaviz, Y. and Polasky, M.E. Foaming Polystyrene with a Mixture of CO2 and Ethanol, J. Cell. Plast., 2006: 42: 127-138.

12.

Dondero, M. , Carella, J. and Borrajo, J. (CO2 + 2-propanol) Mixture as a Foaming Agent for Polystyrene: A Simple Thermodynamic Model for the High Pressure VLE-Phase Diagrams taking into Account the Foam Vitrification, J. Appl. Polym. Sci., 2007: 104: 2663-2671.

13.

Park, C.B. , Cheung, L.K. and Song, S.W. The effect of talc on cell nucleation in extrusion foam processing of polypropylene with CO2 and isopentane. Cell. Polym., 1998 : 17: 221

14.

Handa, Y.P. and Zhang, Z. A New Technique for Measuring Retrograde Vitrification in Polymer-gas Systems and for Making Ultramicrocellular Foams from the Retrograde Phase, J. Polym. Sci. B: Polym. Phys. , 2000: 38: 716-725.

15.

Park, C.B. and Cheung, L.K. A Study of Cell Nucleation in the Extrusion of Polypropylene Foams , Polym. Eng. and Sci., 1997: 37: 1-10.

16.

Goel, S.K. and Beckman, E.J. Generation of Microcellular Polymeric Foams using Supercritical Carbondioxide. I: Effect of Pressure and Temperature on Nucleation, Polym. Eng. and Sci., 1994: 34: 1137-1147.

17.

Carter, R. , Wang, J. , Lee, P.C. and Park, C.B. Continuous Foam Extrusion of Rigid-rod Polyphenylenes, J. Cell. Plast., 2005: 41: 29-39.

18.

Han, X. , Koelling, K.W. , Tomasko, D.L. and Lee , L.J. Continuous Microcellular Polystyrene Foam Extrusion with Supercritical CO2, Polym. Eng. and Sci., 2002: 42: 2094-2106.

19.

Snijders, E.A. , Nelissen, L. and Lemstra, P.J. Water expandable polystyrene (WEPS): Part 4. Synthesis of the water expandable blend of polystyrene and poly(2,6-dimethyl-1,4-phenylene ether). e-Polymers, 2006: 078.

20.

Lee, P.C. , Wang, J. and Park, C.B. Extrusion of Microcellular Open- cell LDPE-based Sheet Foams, J. Appl. Polym. Sci., 2006: 102: 3376-3384.

21.

Mihai, M. , Huneault, M.A. and Favis, B.D. Foaming of Polystyrene/ Thermoplastic Starch Blends, J. Cell. Plast., 2007: 43: 215-236.

22.

Park, C.P. Foam Extrusion of Syndiotactic Polypropelene-Polyethylene Blends, J. Cell. Plast., 2002: 38: 129-138.

23.

Sahnoune, A. Foaming of Thermoplastic Elastomers with Water , J. Cell. Plast., 2001: 37: 149-159.

24.

Chow, T.S. Molecular Interpretation of the Glass Transition Temperature of Polymer Diluent Systems, Macromolecules, 1980: 13: 362-364.

25.

Chiou, J.S. , Barlow, J.W. and Paul, D.R. Plasticization of Glassy Polymers by CO2 , J. Appl. Polym. Sci., 1985: 30: 2633-2641.

26.

Williams, M.L. , Landel, R.F. and Ferry, J.D. The Temperature Dependence of Relaxation Mechanisms in Amorphous Polymers and Other Glass-forming Liquids, J. Amer. Chem. Soc., 1955: 77: 3701-3707.

27.

Utracki, L.A. (2002). Polymer Blends Handbook , New York, Kluwer Academic.

28.

Harrats, C. , Thomas, S. and Groeninckx, G. ( 2006). Micro- and Nanostructured Multiphase Polymer Blend Systems. Phase Morphology and Interfaces, Boca Raton, CRC Press.

29.

Özdemir, C. and Güner, A. Solubility Profiles of Poly(ethylene glycol)/ Solvent Systems, I: Qualitative Comparison of Solubility Parameter Approaches , Euro. Polym. J., 2007: 43: 3068-3093.

30.

Hansen, C.M. ( 2007). Hansen Solubility Parameters. A User’s Handbook , Boca Raton, CRC Press.

31.

Brandrup, J. , Immergut, E.H. and Grulke, E.A. ( 1999). Polymer Handbook, 4th edn, New York, John Wiley & Sons.