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In the current study the effect of different mesoporous silica particles like MCF and SBA-15 on the solid state polymerization (SSP) of poly(ethylene terephthalate) (PET) was investigated. PET nanocomposites containing 1 and 2.5 wt% SBA-15 silica (average pore diameter 4.7 nm) and MCF silica (average pore diameter 14.2 nm) have been prepared by in-situ polymerization. All nanocomposites have been characterized using FTIR spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). SSP was conducted at 220, 230 and 240 °C for 1, 2, 3 and 4 h under vacuum. Intrinsic viscosity (IV) measurements after solid-state polymerization of nanocomposites revealed that PET/SBA-15 nanocomposites exhibited lower IV increase compared to neat PET, while the opposite was observed for PET/MCF nanocomposites, especially for 1 wt% MCF content. A simple kinetic model was employed to predict the time evolution of IV, as well as the carboxyl and hydroxyl content during SSP at different temperatures and reaction times.

In the current study the effect of different clay type, as well as clay organomodifier, on solid state polymerization (SSP) of poly(ethylene terephthalate) (PET) was investigated. PET/clay nanocomposites containing Nanomer I.30E, Cloisite 10A and Laponite have been prepared by melt mixing and their structure was studied by X-ray diffraction measurements. Solid state was conducted at 220, 230 and 240 °C for 1, 2, 3 and 4 h under vacuum application. The I.30E organo-clay exhibited the higher immobilized amorphous fraction. This is due to its better dispersion and exfoliation of the clay nanolayers into the PET matrix, compared to the other organoclays. Intrinsic viscosity (IV) measurements after solid-state polymerization of nanocomposites revealed that IV increase is time and temperature dependent. However, nanocomposites exhibited much lower IV increase compared with neat PET. A simple kinetic model was employed to predict the time evolution of IV, as well as the carboxyl and hydroxyl content during SSP. From the experimental measurements and the theoretical simulation results it was proved that the higher aspect ratio of the nano-clay added, leads to higher inactivated hydroxyls end-groups concentration, higher activation energies and lower transesterification and esterification kinetic rate constants. Increased dispersion of the clay nanolayers in the polymer matrix in addition to increased aspect ratio, leads to better gas barrier properties, reducing the diffusivity and thus the removal of the polycondensation byproducts, i.e. water and EG.

Glassy and rubbery epoxy–clay nanocomposites were synthesized by using various montmorillonite organoclays in order to investigate and compare the effect of the type of alkylammonium ion clay modifier on the structure and properties of the nanocomposites. The organoclays studied were the Nanomer I.28E and I.30E and the Cloisite C10A, C15A and C20A. The functionality (acidity), size and shape of backbone chain, hydrophobicity and polarity were the varying parameters of the organic modifiers that were correlated to the ability of the organoclays to form highly intercalated or exfoliated nanocomposites and to the changes observed in the mechanical (tensile measurements), thermo-mechanical (DMA) and thermal (TGA) properties of the epoxy nanocomposites. The primary alkylammonium ion modifiers with reactive/acidic hydrogen atoms, compared to the quaternary octadecyl, dihydrogenated tallow and benzyl-substituted hydrogenated tallow ammonium ions, were the most effective for the formation of exfoliated clay glassy and rubbery epoxy nanocomposites which exhibited improved properties compared to the pristine epoxy polymers.