Influence of Al 2 O 3 and CuO nanoparticles on the thermal properties of polyester- and epoxy-based nanocomposites Juliana Primo Basilio de Souza • Joa ˜o Marciano Laredo dos Reis Received: 25 April 2014 / Accepted: 30 November 2014 Ó Akade ´miai Kiado ´, Budapest, Hungary 2014 Abstract The modification of polymer properties through the addition of nanoparticles has lead to the development of the so-called nanocomposites. The purpose of this study was to investigate the effect of Al 2 O 3 and CuO nanopar- ticles on the thermo-physical properties of epoxy- and polyester-based nanocomposites. Analysis was carried out for different volume fractions of nanoparticles, ranging from 2.5 to 10 %. The results showed that the glass tran- sition temperature (T g ) varies differently on each matrix and nanoparticles sizes. However, the obtained T g showed no significant change with nanoparticle concentration. The cross-link density studied by DMA for each nanocomposite shows that Al 2 O 3 fillers are responsible for the decrease in cross-link density, while CuO nanoparticles contribute to improve this property. A significant improvement of ther- mal stability of epoxy and unsaturated polyester resins containing CuO nanoparticles was observed. Keywords Polymer matrix  Nanoparticles  Nanocomposite, thermo-physical properties  T g , DSC, DMA Introduction Nanocomposite materials can be described as materials consisting of embedded nanoparticles or nanopores in a solid matrix, polymers for example. They are considered for various applications as their properties can be tuned by varying the particle material, shape, size, and concentra- tion. Also, it was observed a promoting interest in nano- sized reinforced polymers for high technological applica- tions, as coatings, electronic devices and adhesives, auto- motive and aerospace industries [1–3]. The advantage of nanofillers is that they are miscible with the polymer matrix exploiting unique synergisms between the combined materials. Polymer nanocomposites are usually defined as a combination of a polymer matrix and nano-sized particles [4]. The possibilities to improve mechanical or thermal properties, developing a new material, by nanoparticles, have found applications in both academia and industry. The thermal stability of polymer nanocomposites is considered an important factor and its study provides the required information about the period of the applicability for such nanocomposites [5]. The quantitative study of solid-state transformation in various kinds of materials by means of differential scan- ning calorimetry (DSC) and dynamic mechanical analysis (DMA) has been widely discussed [6–10]. While DSC elucidates the kinetics of physical and/or chemical changes of the polymers such as crystallization and degradation [10], DMA provides a sensitive testing system for rapid determination of thermo-mechanical properties as a func- tion of frequency, temperature, or time [6]. One of the main ideas of modifying polymers with oxide nanoparticles is to enhance the material’s thermal and mechanical properties. DMA was frequently used in nanocomposites character- ization since it allows the measurement of two different modulus of the nanocomposites, a storage modulus (E 0 ) and a loss modulus (E 00 ). The first is related to the ability of the material to return or store mechanical energy and the second is related to the ability of the material to dissipate energy a function of temperature. J. P. B. de Souza  J. M. L. dos Reis (&) Laboratory of Theoretical and Applied Mechanics – LMTA, Mechanical Engineering Post Graduate Program – PGMEC, Universidade Federal Fluminense – UFF, Rua Passo da Pa ´tria, 156, Bloco E, sala 216, Nitero ´i, Rio de Janeiro, Brazil e-mail: jreis@mec.uff.br 123 J Therm Anal Calorim DOI 10.1007/s10973-014-4335-9