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Revista mexicana de ingeniería química

Print version ISSN 1665-2738

Rev. Mex. Ing. Quím vol.7 n.2 Ciudad de México Aug. 2008

 

Polímeros

 

Efecto de los aditivos de proceso sobre las propiedades de nanocompuestos de policarbonato con nanopartículas inorgánicas

 

Effect of process additives on the properties of policarbonate nanocomposites with inorganic nanoparticles

 

W. Herrera–Kao y M. Aguilar–Vega*

 

Unidad de Materiales, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Col, Chuburna de Hidalgo, Cp 97200, Mérida Yucatán México. * Autora para la correspondencia. E–mail: mjav@cicy.mx.

 

Recibido 17 de Mayo 2007
Aceptado 10 de Junio 2008

 

Resumen

Se prepararon nanocompuestos de bisfenol–A policarbonato (PC) reciclado, con diferentes concentraciones de nanopartículas de sílica (Aerosil R–972) con y sin ácido esteárico o una nanoarcilla, Cloisite 30B. Se estudiaron materiales con un contenido de 1, 5, y 7.5% en peso de nanopartículas con respecto al peso de PC; además, en algunos casos aquellos que contenían la sílica fueron tratados con 10 y 20% en peso de ayuda de proceso (ácido esteárico) con respecto al peso de sílica. Se determinaron sus propiedades térmicas por medio de Calorimetría Diferencial de Barrido, DSC y sus propiedades mecánicas y dinámico–mecánicas. Los resultados obtenidos muestran una disminución en el valor de la Tg conforme aumenta la concentración de sílica con aditivo o Cloisite 30B. Por otro lado, se observan mayores valores del módulo de tensión y módulo de almacenamiento, E', para las películas preparadas con sílica y 20% de ayuda de proceso o la nanoarcilla Cloisite 30B, y que estos valores aumentan conforme aumenta la concentración de ambas nanopartículas en la matriz de PC. Esto se atribuye a la rigidez proporcionada por las nanopartículas y a su mejor distribución, particularmente con la adición del aditivo para ayuda de proceso. Sin embargo, se observó que la estabilidad térmica disminuye debido a la plastificación producida por la ayuda de proceso, ácido esteárico, y el tensoactivo derivado de un ácido graso usado en el Cloisite 30B.

Palabras clave: policarbonato, nanopartículas, propiedades mecánicas, nanocompuestos.

 

Abstract

Bisphenol A Polycarbonate, PC and silica nanoparticles (Aerosil R–972) or Cloisite 30B nanocomposites were prepared by melt–blending. The silica nanoparticles were treated with 10 and 20 wt % of the stearic acid. Nanocomposites with 1, 5 and 7.5 wt % of filler were tested. The effect of stearic acid concentration on the dispersion of silica nanoparticles was investigated. Thermal properties were obtained by Differential Scanning Calorimetry and mechanical and dynamic mechanical properties were also determined. It was found that Tg decreased with increasing concentration of stearic acid treated silica or Cloisite 30B content due to plasticization of the PC matrix. A fact that is attributed to the presence of increasing concentrations of stearic acid or the tensoactive used in the nanoclay. On the other hand, it was found that the tensile modulus, E, and storage modulus, E', increased with increasing content of silica with additive or Cloisite 30B. This behavior was attributed to an increase in stiffness of the nanocomposite owing to nanoparticles concentration and an improved distribution in the PC matrix of silica treated with stearic acid. However, it was observed that the thermal stability of the nanocomposites, decreases as the concentration of treated silica with stearic acid or Cloisite 30B increases in the composite.

Keywords: polycarbonate, nanoparticles, mechanical properties, nanocomposites.

 

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