Dynamic Mechanical Analysis of Acrylic Copolymer-TiO 2 Nanoparticles
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Dynamic Mechanical Analysis of Acrylic Copolymer-TiO 2 Nanoparticles Rubén Castillo-Pérez1, 2, 4, Mireya L. Hernández-Vargas1, 2, 4, Oscar Hernández-Guerrero3, 4, Bernardo F. Campillo-Illanes1, 4 and Osvaldo Flores-Cedillo4 1
Facultad de Química, UNAM, Ciudad Universitaria D.F. 04510, MEXICO. Posgrado de Ingeniería, Facultad de Química, UNAM, Ciudad Universitaria D.F, 04519, MEXICO. 3 Facultad de Ciencias Químicas e Ingeniería, Centro de Investigación en Ingeniería y Ciencias Aplicadas, UAEM, Av. Universidad 1001, Cuernavaca, Mor. 62209, MEXICO. 4 Instituto de Ciencias Físicas, UNAM, Av. Universidad s/n, Col. Chamilpa, Cuernavaca, Morelos, 62210, MEXICO. 2
ABSTRACT The field of composites materials has evolved from the use of traditional fillers (e.g. carbon and glass fibers) to nanoscale fillers that add unique and often multifunctional properties to the neat polymer. Because nanoparticles have extremely high surface to volume ratios, that alter the mobility of polymer chains near their interfaces, even a small addition of nanoparticles. These components have the potential to drastically transform the properties of the host polymers. While the last decade has observed several advances in the field of nanocomposites, some recent reviews have made it clear that definitive structureproperty relationships are insufficient in the literature. The influence of inorganic TiO 2 nanoparticles on the dynamic mechanical properties and microstructure of copolymer based on Butyl acrylate - Methyl methacrylate - Acrylic Acid has been investigated. The mechanical relaxations of the reinforced copolymer/TiO 2 composites were studied under tension mode. Addition of TiO 2 nanoparticles to acrylic copolymer produced a decrease in the glass transition temperature. Dynamic mechanical analysis (DMA) showed that the local motions associated with the alpha-transition (40°C) are enhanced as the frequency of oscillation increases, i.e. the tan d maximum increases at higher frequencies. The addition of TiO 2 nanoparticles reduces significantly the strength of the alpha-transition. Thus, the cooperative molecular motions involving segments of the molecular chains associated with the alpha-transition were compromised by the presence of TiO 2 nanoparticles resulting in a decrement of the storage modulus.
INTRODUCTION Polymers nanocomposites can be constructed by dispersing nanofiller material into a polymeric matrix. Different types of nanofillers are currently utilized, e.g. nanoclays, carbon nanotubes, electrospun polymeric nanofibers, graphemes, and hybrid organic– inorganic nanoparticles such as polyhedral silsesquioxane (POSS) [1]. The effect of the fillers on the composites properties depends on their concentration, the shape and particle size, aggregate size, surface characteristics, and degree of dispersion. It has been reported that the degree of dispersion of the fillers in a polymer matrix has significant effects on the
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