Nanozirconia (nano-ZrO 2 ) was prepared by the sol-gel method and incorporated into poly(methyl methacrylate) (PMMA) by the in situ bulk polymerization of methyl methacrylate. The structure of the nano-ZrO 2 was confirmed by X-ray diffraction (XRD), transmission electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The structure of the nano-ZrO 2 nanocomposites were studied by differential scanning calorimetry, FTIR spectroscopy, XRD, and scanning electron microscopy, and the results show that there were interactions between the nanoparticles and the polymer. The influence of the nano-ZrO 2 on the thermal stability of PMMA was investigated by thermogravimetric analysis (TGA). The results indicate that nano-ZrO 2 enhanced the thermal stability of the PMMA/nano-ZrO 2 nanocomposites. The effects of the heating rate in dynamic measurements (5-30 C/min) on kinetic parameters such as apparent activation energy (E a ) in TGA both in nitrogen and air were investigated. The Kissinger method was used to determine E a for the degradation of pure PMMA and the PMMA/nano-ZrO 2 nanocomposites. The kinetic results show that the values of E a for the degradation of the nanocomposites were higher than that of pure PMMA in air.
ABSTRACT:The flame-retarded systems consisting of triphenylphosphate (TPP) and nano-poly(phenylsilsesquioxane) spheres (nano-PPSQ) for poly(methyl methacrylate) are reported. The flame-retarded effects were studied by a cone calorimeter test and thermal gravimetric analysis (TGA). The results show that when a part of TPP was substituted with nano-PPSQ, the values of the peak heat release rate of the samples are reduced. The burnt resides were analyzed by the scanning electron microscopy, Raman spectra, and X-ray photoelectron spectroscopy. The results provide evidences that nano-PPSQ can efficiently promote the formation of more dense and compact charred layers composed of varying amounts of graphite and amorphous carbon. The possible mechanisms were discussed. C 2011 Wiley Periodicals, Inc. Adv Polym Techn 30: 33-40, 2011; View this article online at wileyonlinelibrary.com.
The preparation of nano poly(phenylsilsesquioxane) particles (nano-PPSQ) and the influence of nano-PPSQ on the thermal stability and crystallization of polypropylene (PP) were studied. The morphology and thermal stability of PP/nano-PPSQ composites were characterized by scanning electron microscopy (SEM) and the thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix. The TGA results of the PP/nano-PPSQ composites indicated that the incorporation of nano-PPSQ can improve the thermal stability of PP. The crystallization behavior and kinetics of PP/nano-PPSQ composite were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The XRD revealed that the addition of nano-PPSQ influences the crystallinity and crystal size of PP. The Avrami, Ozawa, and combined Avrami/Ozawa (Mo method) equations were applied to describe the crystallization kinetics and estimate the kinetic parameters of mathematical models under the nonisothermal crystallization of PP and PP/nano-PPSQ composites. The results show that nano-PPSQ influences the crystallization temperature and rate.
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