Silicates lamellar surface

In principle, all lamellar minerals may be used as barrier pigments, e.g., micaceous iron oxide [5.167]-[5.169], layer silicates (mica), linear polymeric silicates (wollas-tonite), and talc [5.170], However, untreated mica and talc are not very suitable because they are highly permeable to water [5.57]. The surface can be modified with, for example, silanes or titanates, to reduce water permeability and improve adhesion... 

It is interesting that similar low-temperature weight loss peaks on the DTG curves were also observed for lamellar silicates templated by CTMA+, but the overall shape of the DTG curves was somewhat different [22]. It is not fully clear why these lamellar materials exhibited surfactant decomposition at such low temperatures. This behavior may be related to either properties of their silicate surface or the structural changes in their framework upon heat treatment, or both of these factors, which would promote the Hoffmann elimination at lower temperature [22]. The second of these possible factors may be related to the stress in... 

Several micron-sized layered silicates, such as talcs, can improve the fire retarding behavior of EVA by partial substitution of metal hydroxides. Clerc et al.63 have shown that better fire performance was achieved using higher values of the lamellarity index and specific surface area for four different types of talcs in MH/EVA blends. Expanded mineral and charred layers were formed, similar to intumescent compositions with APP, proving the barrier effect on mass transfer, even at the micron scale for the mineral filler. 

The extender should be acid-resistant (e.g., barytes, talc, mica, china clay, silica, silicates). Minerals with a platelet (lamellar) structure (e.g., talc, mica, and china clay) are particularly suitable for corrosion protection systems since they cover the surface better than particles of other shapes. Better covering makes the paint film less... 

A typical shish-kebab crystalline structure has been foimd by Maiti and Okamoto (2003) and Kim et al. (2001) in polyamide/organoclay nanocomposite and by Choi and Kim (2004) in PP/EPR/talc nanocomposite where a preferential orientation of polymer lamellae perpendicular to the surface of organoclay layers was inspected by TEM measurements. The unique observation of lamellar orientation (Ml the clay layers was ascribed to nucleation and epitaxial crystallization at the interface between layered silicate and polymer matrix especially the surfaces of clay platelets acted as heterogeneous nucleation sites. Orientation of iPP crystals was also enhanced in rPP/PP-MA/o-MMT injection-moulded parts, especially manufactured by dynamic packing injection moulding (Wang et al. 2005). MMT... 

Finally, the BENTONITE sample came from La Serrata de Nijar and was supplied by Minas del Gador. It is a lamellar silicate with a 2 1 structure, a surface area of 83 mVg and a pore volume of 0.381 cmVg. Its montmorilIonite content is over 90%. 

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