Obtenção e Caracterização de Látex Copoliméricos
Cardoso, André Luiz Herzog; Cardoso, Atílio; Galembeck, Fernando
Polímeros: Ciência e Tecnologia, vol.2, n3, p.32-36, 1992
Resumo
Copolimerização em emulsão permite obter produtos bastante diferenciados, com as mesmas matérias primas. A caracterização deste produtos requer métodos sensíveis e de alta resolução. Látex estireno-acrílicos foram preparados por adição simultânea ou sequencial dos monômeros, estireno emetacrilato de butila. Sua caracterização foi feita por microscopia eletrônica de transmissão e por centrifugação em gradientes de densidade, associada à densitometria de espalhamento de luz. Estas técnicas revelaram que as partículas obtidas têm uma morfologia de "core-and-shell", e que os látex preparados por adição sequencial dos monômeros contêm quantidades importantes de partículas homopoliméricas de poliestireno, mas poucas partículas muito ricas em acrílico.
Palavras-chave
Látex copolimérico, caracterização. Látex estireno-acrílico, core-and-shelf. Centrifugação em gradiente de densidade, uso em caracterização de látex. Centrifugação em gradiente de densidade acoplada aespalhamento de luz
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4- Abstracts, 7th International Conference in Surface and Colloid Sciences, Compiêgne, France, 1991.
5- Faraday Discussions of the Chemical Society Nº65, "Colloid Stability", The Chemical Society, London, 1978.
6 - R.M. FITCH - "Colloids", Encyclopedia of Polymer Science and Engineering, Vol. 3, pp. 727-746, John Wiley & Sons, NewYork, 1987.
7- F. LYNEN, U. HENNING, - "Über den biologischen Weg zum Naturkautschuk", Angew. Chem., 22, pp.820-829, (1960).
8-FW. STAVELY, P.H. BIDDISON, M.J. FORSTER, H.G. DAWSON, J.L. BINDER, "The Structure of Various Natural Rubbers", Rubber Chem. Technol., 34, pp. 423-432, (1961).
9 - Y. TANAKA, H. SATO, A. KAGEYU, "Structure and Biosynthesis Mechanism of Natural Cis-Polyisoprene from Goldenrod", Rubber Chem. Technol., 56, pp. 299303, (1983).
10 - C.E. McCOY JR - "The Role of the Surfactant in Emulsion Polymerization", Official Digest, pp. 327-348, April, (1963).
11 - U.S. Pat. 1,732,795 (Oct. 22, 1929). R.P. Dinsmore (to Goodyear Tire and Rubber Co.).
12 - WD. HARKINS, "A General Theory of the Mechanism of Emulsion Polymerization", J. Am. Chem. Soe., 69, pp. 1428-1444, (1947).
13 - WV. SMITH, R.H. EWARl "Kinetics of Emulsion Polymerization", J. Chem. Phys., 16,6, pp. 592-599, (1948).
14 - J-E.L. JONSSON, H. HASSANDER, L.H. JANSSON, B. TORNELL, "Morphology of Two-Phase Polystyrene/Poly (methyl methacrylate) Latex Particles Prepared under Different Polymerization Conditions", Macromoleculas, 24, pp.126-131,(1991).
15 - Z. L1NCHENG, L. XINCUO, L. TIANCHANG - "Study of the Sunthesis and Properties of PBA/PS/PMMA Latex Interpenetrating Polymer Networks", J. Appl. Polym. Sei., 42, pp. 891-900, (1991).
16 - J. BERG, D. SUNDBERG, B. KRONBERG - "Microencapsulation of Emulsified Oil Droplets by in-Situ Polymerization", Polym. Mat. Sei. Eng., 54, pp. 367-369, (1986).
17 - V. L. DIMONIES, M.S. EL-ASSER, J.W VANDERHOFF - "Particle Morphology of Composite Latexes Prepared by Seeded Emulsion Polymerization" Polym. Mat. Sei. Eng., 58, pp. 821-826, (1988).
18 -I. CHO, K-W LEE - "Morphology of Latex Particles Formed by Poly(methyl Methacrylate) - Seed Emulsion Polymerization of Styrene", J. Appl. Polym. Sei., 30, pp. 1903-1926, (1985).
19 - S. LEE, A. RUDIN - "Effects of Surfactants and Polymerization Methods on the Morphology of Particles Formed in "Core-Shell" Emulsion Polymerization of Methyl Methacrylate and Styrene", Makromol. Chem., Rapid Commun., 10, pp. 655-661, (1989).
20 - M. OKUBO, Y. KATSUTA, T. MATSUMOTO - "Rupture of Anomalous Composite Particles Prepared by Seeded Emulsion Polymerization in Aging Period", J. Polym. Sei., Polym Lett. Ed., 18,481-486, (1980).
21 - M.M. TAKAYASU, F. GALEMBECK - "Polystyrene Latex Coagulation. A Study Using Centrifugation in Density Gradients", J. Colloid Interface Sei., aceito.
22 -M.M. TAKAYASU, "Cinética de Coagulação de Látex de Poliestireno", Tese de Mestrado, Campinas, UNICAMP, 1990.
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