Morphology of Isotactic and Syndiotactic Polypropylene Solutions by Liquid Demixing and Crystallization

Hwan Kwang Lee; Su Jin Kim

Journal of Industrial and Engineering Chemistry, Vol.4, No.3, 231-237, September, 1998

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Morphology of Isotactic and Syndiotactic Polypropylene Solutions by Liquid Demixing and Crystallization

Hwan Kwang Lee^†, and Su Jin Kim

Department of Industrial Chemistry, Chungnam Sanup University, Chungnam 350-800, Korea

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The morphology of polypropylene (PP) solutions in dialkyl phthalate formed by liquid demixing and crystallization was investigated for a constant concentration of polymer by optical microscopy with a hot stage. To compare the effects of the stereospecificity of a polymer chain on the morphology, an isotactic PP (i-PP) and a syndiotactic PP (s-PP) of high stereoregularity and of similar molar mass were used. For i-PP solutions in a good solvent where no liquid demixing was involved, a rapid crystallization at a low temperature produced the volume-filling spherulites and a slow crystallization at a high temperature exhibited spherulites followed by dendritic growth. When crystallization was coupled with liquid demixing, a variety of structures were obtained by nonequilibrium competition. It is because the liquid-liquid phase separation could progress until the polymer-rich phase was solidified by crystallization. For s-PP solutions, crystallization without liquid demixing did not produce a spherulitic structure but crystallization coupled with liquid demixing enhanced the spherulite formation.

Keywords:liquid demixing;crystallization;spherulites;isotactic polypropylene solution;syndiotactic polypropylene solution

[References]

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[1] Lee HK, Myerson AS, Levon K, New Advances in Polyolefins, T.C. Chung (ed.), p. 209, Plenum Press, New York (1993)

[2] Lloyd DR, Kim SS, Kinzer KE, J. Membr. Sci., 64, 1 (1991)

[3] Aerts L, Kunz M, Berghmans H, Koningsveld R, Makromol. Chem., 194, 2697 (1993)

[4] Castro AJ, U.S. Patent, 4,247,498 (1980)

[5] Mulder M, Basic Principles of Membrane Technology, Kluwer Academic Publishers, Dordrecht, the Netherlands (1991)

[6] Doane JW, Vaz NA, Wu BG, Zumar S, Appl. Phys. Lett., 48, 369 (1986)

[7] Synthesis of Low-Density Microcellular Materials, in MRS Bull., Materials Research Society, 15, 24 (1990)

[8] Ronner JA, Wassink SG, Smolders CA, J. Membr. Sci., 42, 27 (1989)

[9] Lee HK, Myerson AS, Levon K, Macromolecules, 25, 4002 (1992)

[10] Lee HK, Kim SC, J. Appl. Polym. Sci., 67(1), 159 (1998)

[11] Flory PJ, Principles of Polymer Chemistry, Cornell University Press, Ithaca, NY (1953)

[12] Brandrup J, Immergut EH, Polymer Handbook, 3rd ed., John Wiley and Sons, New York (1989)

[13] Keith HD, Padden FJ, J. Appl. Phys., 34, 2409 (1963)

[14] Keith HD, Padden FJ, J. Appl. Phys., 35, 1270 (1964)

[15] Goldenfeld N, J. Cryst. Growth, 84, 601 (1987)

[16] Tanaka H, Nishi T, Phys. Rev., A, 39, 783 (1989)

[17] Sanchez IC, DiMarzio EA, Macromolecules, 4, 677 (1971)

[18] Shah JK, Lahti LE, Ind. Eng. Chem. Prod. Res. Dev., 12, 304 (1973)

[19] Nishijima Y, Oster G, J. Polym. Sci., 19, 337 (1956)

[20] Cahn JW, Hilliard JE, J. Chem. Phys., 31, 688 (1959)

[21] Svoboda P, Kressler J, Inoue T, J. Macromol. Sci.-Phys., B35, 505 (1996)

[22] Thomann R, Wang C, Kressler J, Jungling S, Mulhaupt R, Polymer, 36(20), 3795 (1995)

[23] Loos J, Petermann J, Polymer, 37(19), 4417 (1996)

[24] Schumacher M, Lovinger AJ, Agarwal P, Wittmann JC, Lotz B, Macromolecules, 27(23), 6956 (1994)