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Novo Hamburgo, Brazil

Bianchi O.,University of Caxias do Sul | Martins J.N.,Federal University of Rio Grande do Sul | Martins J.N.,Feevale University Feevale | Luvison C.,University of Caxias do Sul | And 4 more authors.
Journal of Non-Crystalline Solids | Year: 2014

Melt crystallization of polyhedral oligomeric silsesquioxane (POSS) was studied by differential scanning calorimeter (DSC), X-ray diffraction (XRD), Fourier transformed infra-red spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM analysis showed that POSS samples are aggregated in micrometric size. Additionally, FTIR spectra confirmed intermolecular interactions among carbonyl groups. All samples showed that the Ozawa exponent ranged from 1 to 2.6 and the Ozawa crystallization rate constant was found to decrease with increasing temperature and reduction of average X(T). This suggests that these POSS crystallized slower as the temperature increased. The ΔEX(T) values for isobutyl POSS increased monotonically until X(T) = 0.4, and for the methacryl isobutyl POSS the ΔEX(T) values decreased. After this point ΔEX(T) showed similar values for both POSS samples. The presence of the methacryl radical in POSS cages interfered in the crystallization process due to the hysteric hindrance among POSS-POSS cages. © 2014 Elsevier B.V. Source

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