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Sodium-montmorillonite (MMT) was modified with two types of AP-POSS and OA-POSS and dual-surfactants (POSS with a ditallow-based second surfactant: 04AP-POSS/08DTDMA and 04OA-POSS/08DTDMA), respectively, via ion-exchange reaction. The interlayer space, interlamellar structure, thermal and surface properties of these organo-montmorillonites were investigated by X-ray diffraction, thermogravimetric analysis, and contact angle measurement. The interlayer space of POSS modified clay was strongly dependent on the arrangement of POSS surfactants, but less on the POSS concentration. The POSS modified montmorillonites have partially exchanged silicate surfaces and good thermal stabilities due to steric hindering and thermal stability of the POSS molecules. Dual-surfactant modified montmorillonites showed higher exchange ratio and possessed better compatibility with PA12 due to the lower interfacial free energy. Polyamide 12-montmorillonite nanocomposites were prepared by conventional melt compounding with the four POSS based organo-montmorillonites. The best dispersion of modified montmorillonite was observed for 3 mass% 04AP-POSS/08DTDMA/MMT filled PA12 nanocomposites, which resulted in the best mechanical performance with an increase of 60% in tensile modulus and 10% in yield strength, respectively, compared to that of pure PA12. Compatibility between montmorillonites and polymer was not the only key factor affecting dispersion, thermal stability and interlayer space were also crucial for good dispersion of montmorillonites in polymer matrix.

This paper reports the application of dual-surfactant, thermally stable organoclays (OC) to the production of poly(butylene terephthalate) (PBT) nanocomposites by the masterbatch method. A common failing of single surfactant organoclays is their thermal instability at high polymer processing temperatures, such as that used for PBT (235 °C). This can be overcome by first modifying the clay mineral with a thermally stable surfactant such as aminopropyl-POSS (AP-POSS). In this study, sodium montmorillonite (Na+Mt) was sequentially modified with AP-POSS and ditallowdimethylammonium chloride by ion-exchange reaction to give dual-surfactant organoclay (OC). This dual surfactant clay mineral was then used to prepare masterbatches comprising 40% clay mineral intercalated with CBT polymerized by ring-opening polymerization. The masterbatches were then processed with PBT by melt compounding to give PBT-clay nanocomposites whose morphology was studied by XRD and TEM and mechanical properties were assessed by tensile testing. Spectral examination showed that the dual surfactant clay mineral was readily intercalated by PBT, while electron microscopy revealed that an intercalated/exfoliated micromorphology was achieved. The elastic modulus and tensile strength of PBT were increased by inclusion of dual-surfactant clay, while the reduction in elongation typically associated with nanoclay inclusion was mitigated by the dual surfactant clay. The possible antagonism of the catalyst used in the ring-opening polymerization and the reinforcing effect of the dual surfactant clay is also discussed.