Morphology, mechanical properties and thermal degradation kinetics of PMMA-zirconia nanocomposites prepared by melt compounding

Abstract

Abstract. Zirconia nanoparticles were synthesized by means of a sol-gel method and embedded in poly(methyl methacrylate) (PMMA) by melt compounding. The zirconia was well dispersed in the PMMA matrix, with only a few clusters, especially for the highest investigated zirconia content. NMR results showed heteronuclear dipolar interactions involving the carbons and the surrounding hydrogen nuclei. The effect of the amount of zirconia, in the range of 1-5!wt%, on the thermomechanical properties and thermal degradation kinetics of PMMA was also investigated by means of dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), and Fourier-transform infrared spectroscopy (FTIR). The presence of zirconia showed a decrease in the storage and loss moduli at lower temperatures, probably due to a plasticization effect. The presence of zirconia in PMMA slightly increased its thermal stability, but the activation energies of thermal degradation for the nanocomposites were significantly lower, at degrees of conversion higher than 0.3, than those of pure PMMA.

The effect of silica nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of polycarbonate

“…The increase in activation energy with an increase in degree of conversion was also observed by us when investigating PMMASiO 2 /TiO 2 ÁZrO 2 nanocomposites [13,18,19] and by several other authors [20][21][22]. It was generally explained as changes in the degradation mechanism with increasing degree of conversion.…”

Influence of the modification, induced by zirconia nanoparticles, on the structure and properties of polycarbonate

“…The TEM micrographs of the ZrO 2 powder, reported in our previous paper [21], showed aggregates with a large number of particles (more than 30) of different sizes. In each aggregate the bigger, quite thick particles (around 200-400 nm) were surrounded by smaller spongy particles (50-100 nm).…”

P(VDF-TrFE)/ZrO2 Polymer-Composites for X-ray Shielding

“…However, this intense absorbance band is reported to be present in the PMMA/ZrO 2 nanocomposites made by different methods, for all ZrO 2 concentrations studied. 10,13,16 It is also present in P(VDF-TrFE)/PMMA blends, for all PMMA contents, but downshifted to 1735 cm -1 . 17 Although a conclusive explanation to this phenomenon requires additional investigations and calculation by molecular modeling, we suggest that the absorption band at 1645 cm -1 could be originated by the weakening of the C=O bond, which could also be sharing its electronic charge with the P(VDF-TrFE) copolymer chain, decreasing its intensity at 1745 cm -1 .…”

“…The next step conducts to the formation of nanocomposites by mechanically mixing the polymeric material with the nanoparticles. [10][11][12][13] Organic acids have been utilized to improve the compatibility and even to enhance the reactivity of nanoparticles with organic matrix. The surface modifiers from methacrylate group make the nanoparticles polymerizable in radical polymerization.…”

“…14 Also, in this respect, we note that the FTIR data collected at higher temperatures for PMMA/ZrO 2 nanocomposites reported in the literature have clearly demonstrated the absence of these absorption bands above 100°C. 10,16 DSC thermograms were collected in order to detect changes in the P(VDF-TrFE) 50/50 crystalline structure provoked by the addition of ZrO 2 -MMA nanoparticles. This DSC data could be of great help in view of well known ferroelectric behavior of P(VDF-TrFE) that presents a ferroelectric-to-paelectric (f-p) phase transition for trifluorethylene contents ranging from 18 to 63 mol%.…”