Melt crystallization kinetics of polyhedral oligomeric silsesquioxane under non-isothermal conditions

Melt crystallization of polyhedral oligomeric silsesquioxane (FOSS) 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 PUSS 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 PUSS crystallized slower as the temperature increased. The Delta E-X(T) values for isobutyl PUSS increased monotonically until X(T) = 0.4, and for the methacryl isobutyl PUSS the Delta E-X(T) values decreased. After this point Delta E-X(T) showed similar values for both PUSS samples. The presence of the methacryl radical in PUSS cages interfered in the crystallization process due to the hysteric hindrance among PUSS-PUSS cages. (C) 2014 Elsevier B.V. All rights reserved.