Octadecylamine-modified montmorillonite

The effect of stereochemistry and polydispersity on nanocomposite properties has yet to be explored fully. An intriguing result was obtained by Quijada et al. who performed melf mixing of PP-g-MA with octadecylamine-modified montmorillonite or hectorite, then blended these materials with different isotactic polypropylenes. Nanocomposites with better clay exfoliation were obtained using metallocene polypropylene compared to Ziegler-Natta polypropylene, presumably because of ifs lower polydispersity. While stereoselective metallocene catalysts have been used successfully for in situ propylene polymerization in combination with clay supports (see Section 5.2.2.2), the materials properties of these nanocomposites have thus far received insufficienf affention. 

A commercially available organoclay based on a layered silicate (montmorillonite modified by dimethyldistearylammonium cation exchange) was used. The content of the quaternary ammonium compound was 38 wt%. Octadecylamine-modified montmorillonite is used to study the thermal stability of organoclay. 

Graphite modified with octadecylamine Optical microscopy Organically modified montmorillonite Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)... 

The influence of the inclusion size, shape, and surface treatment on the gas permeability of polyethylene in its micro- and nanocomposites has been investigated in various papers.Kato et al. report the N2 permeability of nanocomposites based on polyethylene (PE) melt compounded with maleic anhydride grafted polyethylene (MA-g-PE) and octadecylamine (C18-MMT) modified montmorillonite. The gas permeability coefficient for all the prepared samples are reported in Fig. 11.8. Interestingly, polyethylene, maleic anhydride grafted polyethylene, a 70/30 blend of PE/MA-g-PE and a blend of PE/MA-g-PE/MMT have almost the same permeability coefficient. Only the composites obtained by mixing the polymeric matrices with the modified montmorillonite show for PE/MA-g-PE/C18-MMT (PECHl) a decrement of 30% in permeability and for MA-g-PE/C18-MMT (PECH3) a decrement of 35%. The differences in the gas barrier property were attributed to the different dispersion of the clay silicate layers in the matrix. 

Sodium montmorillonite/PVK composites have been prepared by free radical polymerization using cerium ammonium nitrate [223]. Sodium montmo-rillonite was used in the form of nanolayers both of hydrophilic and organophilic types, modified with octadecylamine and trimethyl stearyl ammonium. 

Na-montmorillonite (MMT) was purified by dispersion of crude clay into deionized water and separation of non-colloidal impurities. To obtain cation exchange process, the purified MMT was swollen in deionized water for 24 h agitation at room temperature and a certain quantity of 1-octadecylamine was added. The system was maintained at around 68 °C for about 4 h and then filter and repeatedly washed with deionized water. The product was then dried, crushed, and sieved with 325-mesh to obtain organically modified montorillonite (OMMT). The main objective for the modification of nanoclay montmorillonite consists in or-ganophilization of clay in order to improve the compatibility with epoxy resin blends. Otherwise, the polymer and the clay will form a separate phase system with a low interface among the various components. 

The oil absorption parameter was calculated on the basis of the amount of dibutyl phthalate oil absorbed by the filler particles. This parameter can characterize the tendency of the filler to create own structure in elastomer matrix. The values of this parameter for modified fillers were, respectively 65,2 g/lOOg for MMT I.30E modified with octadecylamine, 78 g/lOOg for MMT 1.31 PS modified with octadecylamine and aminepropyltriethoxysilane, 72,1 g/lOOg for MMT 1.34 TCN. The montmorillonites modified with ionic liquids characterized the similar values of oil absorption parameters (MMT mod. ADDMA 75,2 g/lOOg, MMT mod. SDDMA 82,5 g/lOOg)... 

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