Polímeros

 

Rheological characterization and thermal stability of triblock copolymers-modified asphalt reinforced with montmorillonite nanoparticles in physical mixing

 

Caracterización reológica y estabilidad térmica de asfalto modificado con copolímeros tribloque y montmorillonita en un mezclado físico

 

M.A. Vargas-Hernández^1* and H. Vázquez-Torres²

 

¹ Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico S/N, Valle de Anáhuac, 55210 Ecatepec de Morelos, Estado de México. *Corresponding author. E-mail: angelesvh@yahoo.com Tel. 55-71-43-92.

² Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa. Av. San Rafael Atlixco 186, col. Vicentina, México, D.F. CP. 09340.

 

Received June 7, 2014
Accepted May 22, 2015

 

Abstract

Effects of montmorillonite (MMT) on the rheological, thermal stability and morphological properties of triblock copolymer modified asphalts are investigated. Modified asphalts were prepared by successively mixing the clay and SBS, SIS, or SEBS with the asphalt AC-20. Results show that the MMT modified asphalt may form an intercalated or exfoliated structure. MMT increased slightly both the softening point and the viscosity of the modified asphalts at high temperatures. Furthermore, the modified asphalts exhibited a relatively higher complex modulus and, in consequence, displayed enhanced viscoelastic properties, which improve its resistance to rutting at high temperatures. The high-temperature storage property can be increased by improving the compatibility between polymer and asphalt The morphology observed by optical microscopy revealed the better compatibility between triblock asphalt/polymer/MMT, thus influencing the final rheological properties of the studied systems. Indeed, asphalt or asphalt/polymer blends gave a typical terminal relaxation behavior for polymer (G'~ w², G"~ w¹), which is modified by the addition of MMT particles. Furthermore, the activation energy of nanocomposites resulted slightly higher than that of asphalt/polymer blends without MMT.

Keywords: asphalt, montmorillonite, triblock polymers SBS, SIS, SEBS, modified asphalt, rheology, storage stability.

 

Resumen

Se estudió el efecto de la montmorillonita (MMT) sobre las propiedades reológicas, estabilidad térmica y morfología del asfalto AC-20 modificado con copolímeros tribloque. El asfalto modificado (AM) se preparó por mezclado sucesivo de nanopartículas y polímeros SBS, SIS y SEBS. Los resultados obtenidos muestran que la arcilla puede formar distribuciones intercaladas y/o exfoliadas. La presencia de la MMT en el AM aumenta ligeramente la temperatura de ablandamiento y la viscosidad del asfalto a temperaturas altas y disminuye el grado de penetración. Adicionalmente, estos materiales muestran un aumento en los módulos elástico y viscoso, lo que indica un considerable mejoramiento en la resistencia a la deformación permanente por acanalamiento a temperaturas elevadas. La estabilidad térmica del asfalto modificado aumenta con la presencia de MMT, debido a la mejora de la compatibilidad entre el asfalto y el polímero por sus interacciones con la arcilla. En efecto, la morfología del AM observada por microscopía optica presenta una reducción en el tamaño de partícula del polímero en el sistema ternario asfalto/polímero/MMT, lo cual se ve reflejado en el mejoramiento de la compatibilidad y de sus propiedades viscoelásticas. El asfalto AC-20 y las mezclas binarias polímero/asfalto presentan una relajación terminal característica del polímero (G' ~ w², G" ~ w¹),). Por su parte, las mezclas asfalto/polímero/MMT muestran un cambio en el espectro de relajación terminal (G' y G" ~ w¹), además de un ligero aumento en la energía de activación.

Palabras clave: asfalto modificado, arcilla MMT, polímeros tribloque, reología, estabilidad térmica.

 

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References

Baochang, Z., Man, X., Dewen, Z., Huixuan, Z., Baoyan, Z. (2009). The effect of styrene-butadiene-rubber/montmorillonite modification on the characteristics and properties of asphalt. Construction and Building Materials 23, 3112-3117.         [ Links ]

Chung, J.W., Han, S.J., Kwak, S.Y. (2008). Dynamic viscoelastic behavior and molecular mobility of acrylonitrile-butadiene copolymer nanocomposites with various organoclay loadings. Composites Science and Technology 68, 1555-1561.         [ Links ]

Fang, C., Yu, R., Zhang, Y., Hu, J., Zhang, M., Mi, X. (2012). Combined modification of asphalt with polyethylene packaging waste and organophilic montmorillonite. Polymer Testing 31, 276-281.         [ Links ]

Herrera R., García G., Xicotencalt H. and Medina L. (2012). On the effect of the composition of the elastomeric block of SBS and SEBES block polymers on the rheological properties of modified asphalt. Revista Mexicana de Ingeniería Quimica 11, 133-144.         [ Links ]

Kuo, W.Y., Huang, J.S., Yu, B.Y. (2011). Evaluation of strengthening through stress relaxation testing of organo-modified montmorillonite reinforced cement mortars. Construction and Building Materials 25, 2771-2776.         [ Links ]

Markanday, S. S., Stastna, J., Polacco, G., Filippi, S., Kazatchkov, I., Zanzotto, L. (2010). Rheology of Bitumen Modified by EVA-Organoclay Nanocomposites. Journal of Applied Polymer Science 118, 557-565.         [ Links ]

Ouyang, C., Wang, S., Zhang, Y., Zhang, Y. (2005). Preparation and properties of styrene-butadiene-styrene copolymer/kaolinite clay compound and asphalt modified with the compound. Polymer Degradation and Stability 87, 309-317.         [ Links ]

Ouyang, C., Wang, S., Zhang, Y., Zhang, Y. (2006). Low-Density Polyethylene/Silica Compound Modified Asphalts with High-Temperature Storage Stability. Journal of Applied Polymer Science 101, 472-479.         [ Links ]

Ouyang, C., Wang, S., Zhang, Y., Zhang, Y. (2006). Thermo-rheological properties and storage stability of SEBS/kaolinite clay compound modified asphalts. European Polymer Journal 42, 446-457.         [ Links ]

Perez-Lepe, A., Martínez-Boza, F.J., Attane, P., Gallegos, C. (2006). Destabilization Mechanism of Polyethylene-Modified Bitumen. Journal of applied Polymer Science 100, 260-267.         [ Links ]

Polacco, G., Krìz, P., Filippi, S., Stastna, J., Biondi, D., Zanzotto, L. (2008). Rheological properties of asphalt/SBS/clay blends. European Polymer Journal 44, 3512-3521.         [ Links ]

You, Z., Mills-Bealea, J., Foley, J.M., Roy, S., Odegard, G.M., Dai, Q., Goh, S.W. (2011). Nanoclay-modified asphalt materials: Preparation and characterization. Construction and Building Materials 25, 1072-1078.         [ Links ]

Yu, J., Wang, L., Zeng, X., Wu, S., Li, B. (2007). Effect of Montmorillonite on Properties of Styrene-Butadiene-Styrene Copolymer Modified Bitumen. Polym. Eng. Sci., 47, 1289-1295.         [ Links ]

Yu, J., Zeng, X., Wu, S., Wang, L., Liu, G. (2007). Effect of Montmorillonite on Properties of Styrene-Butadiene-Styrene Copolymer Modified Bitumen. Materials Science and Engineering A 447, 233-238.         [ Links ]

Yu, J.Y., Feng, P.C., Zhang, H.L., Wu, S.P. (2009). Effect of organo-montmorillonite on aging properties of asphalt. Construction and Building Materials 23, 2636-2640.         [ Links ]

Zare-Shahabadi, A., Shokuhfar, A., Ebrahimi-Nejad, S. (2010). Preparation and rheological characterization of asphalt binders reinforced with layered silicate nanoparticles. Construction and Building Materials 24, 1239-1244.         [ Links ]

Zhang, J., Wang, J., Wu, Y., Wang, Y., Wang, Y. (2008). Preparation and properties of organic palygorskite SBR/organic palygorskite compound and asphalt modified with the compound. Construction and Building Materials 22, 1820-1830.         [ Links ]

Zhang, J., Wang, J., Wu, Y., Sun, W., Wang, Y. (2009). Investigation on Thermo-Rheological Properties and Stability of SBR Modified Asphalts Containing Palygorskite Clay. Journal of Applied Polymer Science 113, 2524-2535.         [ Links ]

Zhang, H., Yua, J., Wang, H., Xue, L. (2011). Investigation of microstructures and ultraviolet aging properties of organo-montmorillonite/SBS modified bitumen. Materials Chemistry and Physics, 129, 769-776.         [ Links ]