Organo-clay fillers

TEM microphotographs of the so-obtained samples show the typical morphology of intercalated nanocomposites. Furthermore with organo-modified fillers, in addition to small stacks of intercalated clay particles, a limited amount of completely exfoliated/delaminated silicate sheets coexists with the intercalated aluminosilicates layers. 

While organo-silane treatments are extensively used in both thermoset and elastomer applications, their use in thermoplastics has so far been somewhat restricted. This is because they do not react with the surface of calcium carbonate, one of the principal fillers used in this type of polymer and because of the lack of a suitable reactive functionality for most of the thermoplastic polymers. Today they are principally used in conjunction with glass fibres, calcined clays, aluminium and magnesium hydroxides, micas and wollastonite. The main thermo-... 

Pluta, M., Paul, M.A., Alexandre, M., Dubois, P. Plasticized polylactide/clay nanocomposites. I. the role of filler content and its surface organo-modification on the physico-chemical properties. J. Polym. Sci., Part B Polym. Phys. 44, 299-311 (2006)... 

Furthermore, the introduction of organo-modified clays in an epoxy resin was found to lead to the formation of a stronger interface with E-glass fibers, with an increase of the interfacial shear strength of around of 30% for a filler content of 5 wt% [11]. 

Non-reinforcing fillers such as clay and calcium carbonate may be enhanced with surface treatments such as carboxylated polybutadiene, calcium stearate, or an organo-silane coupling agent. 

If chemical treatment of the matrix polymer blend or the filler needs to be avoided or the interaction between the components is insufficient, then a third component, such as a polymer compatibilizer [20], can be added to the composite. Compatibilizers are added especially to polyolefin/nanoclay composites prepared by melt blending because the organo modification of the clay is seldom sufficient to create a favorable interaction between polymer chains and the clay sheets [21]. The interfacial adhesion between the compatibilizer and clay galleries is influenced by the functionality and its concentration, molecnlar weight and molecular weight distribution of the compatibilizer, and the mass ratio of the compatibilizer to the clay [22]. 

Secondly, we need to consider the position of the modifier. The clay chemistry dictates that conventional onium ions will only become firmly attached to the basal plate surfaces, leaving the edges and other faces untreated. These untreated surfaces will probably have sites amenable to treatment with more conventional additives, such as organo-silanes. Thus, mixed surface treatments may be most effective in covering all active surface sites. Indeed, it has been reported that all common mineral fillers are amphoteric to some extent and therefore have sites for adsorbing both acidic and basic surface treatment additives [26]. 

Nanocomposite conventional mesoscale fibers (textile fibers that carry nanoparticulate filler) are produced via conventional fiber-spinning techniques by incorporating well-dispersed nanoparticles into the spinning dope. For instance, an intercalated poly(ethylene terephthalate) (PET)/organo-montmorillonite (MMT) nanocomposite prepared by in situ polymerization of the polyester in the presence of MMT clay was successfully melt spun into microfibers (Guan, G.-H., et al. 2005). Melt-spun conventional fibers of... 

Titanium dioxide is by far the most effective white pigment a compounder can use in a rubber compound. It has superior opacity, brightness, and hiding power over all other white pigments or fillers. However, it is also more expensive than other white fillers such as special water-washed clays, calcium carbonate, and talcs. Occasionally, organo-titanates are used in rubber formulations to improve filler dispersion, that is, the compound s rheology. 

The presence of a tiny amount of filler, i.e., as low as 3 wt% inorganics, allows to increase the elastic modulus from 216 MPa for unfilled PCL to around 280 MPa for intercalated nanocomposites obtained with organo-modified clays. It is worth pointing out that increasing the clay content enhances the material stiffiiess (Figure 1). 

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