ESTABILIDADE TÉRMICA E FLAMABILIDADE DE NANOCOMPÓSITOS DE POLIETILENO DE ALTA MASSA MOLAR PRODUZIDOS POR POLIMERIZAÇÃO IN SITU
THERMAL STABILITY AND INFLAMMABILITY OF NANOCOMPOSITES OF HIGH DENSITY POLYETHYLENE OBTAINED BY IN SITU POLYMERIZATION
Sara Pereira de Agrela, Luiz Rogério Pinho de Andrade Lima, Rosemário Cerqueira Souza
Resumo
Nanocompósitos de polietileno de alta massa molar com argila, grafita ou talco foram produzidos utilizando polimerização in situ direta em solvente usando um sistema catalítico tipo Ziegler (TiCl4 e trietilalumínio em hexano). O polímero produzido apresentou uma massa molar alta e degradação térmica em atmosfera inerte em temperatura acima de 400ºC. A degradação térmica dos polímeros nos nanocompósitos foi deslocada para temperaturas um pouco mais altas (até próximo de 500ºC) indicando um aumento da estabilidade térmica da matriz polimérica. Os testes de flamabilidade mostraram um efeito de redução ou atenuação da progressão das chamas para todos os nano-compósitos devido ao efeito de barreira para gases e compostos voláteis.
Palavras-chave
Abstract
High density polyethylene-clay, graphite or talc composites were produced using direct solvent in situ polymerization using a Ziegler catalyst system (TiCl4 and triethylaluminum in hexane). The produced polymer had a high average molecular weight and in inert atmosphere presents a thermal degradation above 400ºC. The thermal degradation of the polymers in the nanocomposites was shifted for higher temperature (until close to 500ºC) indicating an improvement in the thermal stability of the polymeric matrix. The inflammability tests clearly showed a retardation or attenuation effect of the flames progression for all nanocomposites due to the barrier effect for gases and volatile compounds.
Keywords
Referências
1 Paul DR, Robeson LM. Polymer nanotechnology: nanocomposites. Polymer. 2008;49:3187-3204.
2 Silva BL, Nack FC, Lepienski CM, Coelho LAF, Becker D. Influence of intercalation methods in properties of clay and carbon nanotube and high density polyethylene nanocomposites. Materials Research. 2014;17:1628-1636.
3 Araujo EM, Barbosa R, Rodrigues AWB, Melo TJA, Ito EN. Processing and characterization of polyethylene/Brazilian clay nanocomposites. Materials Science and Engineering A. 2007;445-446:141-147.
4 Suarez JCM, Bonello CMC, Eltom AE, Mano EB. Comportamento fisico-químico de uma mistura LDPE/HDPE irradiada: efeito da atmosfera. Tecnologia em Metalurgia e Materiais. 2005;2:18-23.
5 Pandey JK, Reddy KR, Kumar AP, Singh RP. An overview on the degradability of polymer nanocomposites. Polymer Degradation & Stability. 2005;88:234-250.
6 Jin YH, Park HJ, Im SS, Kwak S. Polyethylene/clay nanocomposite by in-situ exfoliation of montmorillonite during Ziegler-Natta polymerization of ethylene. Macromolecular Rapid Communications. 2002;23:135-140.
7 Ramazani A, Tavakolzadeh F, Baniasadi H. In situ polymerization of polyethylene/clay nanocomposites using a novel clay-supported Ziegler-Natta catalyst. Polymer Composites. 2009;30:1388-1393.
8 Nikkhah S, Ramazani A, Baniasadi H, Tavakolzadeh F. Investigation of properties of polyethylene/clay nanocomposites prepared by new in situ Ziegler-Natta catalyst. Materials & Design. 2009;30:2309-2315.
9 Abedi S, Abdouss M, Haghighi M, Sanjani N. PE/clay nanocomposites produced via in situ polymerization by highly active clay-supported Ziegler-Natta catalyst. Polymer Bulletin. 2013;70:1313-1325.
10 Haag RB, Silva JC. Process for preparing a Ziegler type catalytic system and process for preparing ultra high molecular weight polyethylene. United States patent US 4983693. 1991.
11 Valanzuela-Diaz FR. Preparação a nível de laboratório de algumas argilas organofílicas [tese]. São Paulo: Universidade de São Paulo; 1994.
12 Bruce Prime R, Bair HE, Vyazovkin S, Gallagher PK, Riga A. Thermogravimetric Analysis (TGA). In: Menczel JD, Bruce Prime R, editors. Thermal analysis of polymers: fundamentals and applications. Hoboken: John Wiley & Sons; 2009.
13 Alexander LE. X-ray diffraction methods in polymer science. New York: Wiley-Interscience; 1970.
14 Tang Y, Lewin M. New aspects of migration and flame retardancy in polymer nanocomposites. Polymer Degradation & Stability. 2008;93:1986-1995.
15 Hull TR, Stec AA, Nazare S. Fire retardant effects of polymer nanocomposites. Journal of Nanoscience and Nanotechnology. 2008;8:1-9.
16 Khaghanikavkani E, Farid MM. Thermal pyrolysis of polyethylene: kinetic study. Energy Science and Technology. 2011;2:1-10.
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