Thermooxidative degradation of LDPE nanocomposites: Effect of surface treatments of fumed silica and boehmite alumina

Abstract

Fumed silica (FS) and synthetic boehmite alumina (BA) with and without surface treatments were incorporated in 5 wt. % in low density polyethylene (LDPE) through melt blending. FS was treated by hexadecyl silane, whereas BA by octyl silane and alkylbenzene sulfonic acid.The related nanocomposites were subjected to pyrolysis gas chromatography-mass spectomertry (Py-GC-MS) and thermogravimetric analysis (TGA) under isothermal and dynamic conditions, respectively. Py-GC-MS results proved that the thermal degradation mechanism did not change in presence of the nanofillers. The latter suppressed the formation of high molecular weight hydrocarbons and affected the relative amounts of diene/alkene/alkane fragments for each hydrocarbon fraction.Dynamic TGA scans were registered at different heating rates in air. The activation energy (E α ) of thermoxidative degradation was calculated by the Ozawa-Flynn-Wall (OFW) method at various degradation degrees. E α of the LDPE nanocomposites depended on both specific surface area and surface treatment of the nanofillers used. The former enhanced whereas the latter decreased the activation energy for the LDPE-FS nanocomposites. By contrast, E α was slightly increased for the surface treated LDPE-BA nanocomposites.

Preparation and Characterization of Alumina HDPE Composites

“…Similar results were reported by other researchers on different types of polymer matrices, like PE (HDPE and LDPE) and PP [2,21,26]. Generally, the improvement in the thermal stability could be attributed to the physical origin of the nanoparticles and due to their barrier effect towards diffusion of gaseous degradation products [27]. The FTIR was performed to analyze the chemical composition of the prepared PNCs and to confirm chemical homogeneity of the fillers dispersed in the polymer matrices.…”

Effects of Fumed Silica and Draw Ratio on Nanocomposite Polypropylene Fibers

“…Analogous improvement has been reported for PP fibers containing fumed silica [ 14 ] or polyethylene plates with fumed silica or hydrotalcite [ 27 , 40 , 46 ]. Improved thermo-oxidative stability, manifested by the shifts of T 0.1 , T 0.5 and T 0.8 toward higher temperatures, can be ascribed to the barrier effect of the nanoparticles hampering the diffusion of the gaseous degradation products [ 53 ]. T 0.1 for the composite with 2 vol % of AR974, which is slightly lower than the corresponding temperature of other PP-silica nanofibers, can tentatively be related to possible aggregate formation accounting for less effective barriers to diffusion.…”

Flame retarded poly(lactic acid): A review

“…Besides, volatile gas released by PLA during degradation was greatly reduced in the presence of Al-SBA-15, which was attributed to the adsorption and retardation of released volatile gas via the labyrinth effect. The latter was often quoted as the major contributing factor of the improved thermal resistance of polymeric nanocomposites [75].…”