Lamellar talc

Luzenac 1445, 20M0, 20M00S, OOS - highly lamellar talc with low abrasiveness from French Pyrenees... 

Rio Tlnto has also looked at how very fine lamellar talcs allow thtn-waH blow-molded HDPE bottles and packaging. Here, extra fine 1- to 2-itm Luzenac talc reportedly stiffens and strengthens the resin efficiently without excessively reducing... 

Schiefer-spat, m. slate spar (lamellar variety of calcite). -stein, n. slate, -talk, m. talc slate, indurated talc, -teer, m. shale tar. -teerbl,... 

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... 

Talc particles of different lamellarity and specific surface area have been incorporated into polyethylene vinyl acetate (EVA) copolymer/magnesium hydroxide (MH) composite system.63 The fire retardancy of this system has been studied and compared with formulations containing only EVA and MH and formulations containing EVA, MH, and organomodified montmorillonites (oMMT). It was observed that talc with higher lamellar index showed fire behavior similar to that of EVA/MH/ oMMT system with some intumescence. 

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 particle morphology of the talc materials from the various vendors was investigated with scanning electron microscopy. All the talc materials were found to be flaky and plate-like in appearance as shown in Figures 6-8. When viewed at 3000x, the lamellar orientation of the plates is evident, as well as the presence of smaller crystals growing on the surface. 

Mistron 705, 754, Monomix, Super-20, Monomix-E, PE-60 - microcrystalline talc Naintsch E, SE, ASE, - extremely lamellar structure and talcs containing dolomite Luzenac OOC, 20M0, lOMO, Steabright, Steaopac - various finishes in decorative and industrial paints... 

To our knowledge, only few studies were done on the determination of the surface heterogeneity of solids using IGC at finite concentration, if we exclude the works recently done in our group. In this instance, we first examine the case of solids that are heterogeneous on a quite macroscopic scale, originating generally from a lamellar structure like clays, micas or talcs. 

The last example of macroheterogeneous lamellar solids concerns talcs that are common fillers for polyolefinic matrices because their crystalline structure induces the crystallization of, say, the polypropylene matrix. Of course, talcs are natural products whose superficial properties depend on the location of the mine. Their characteristics are reported in Table 3. 

Inorganic (asbestos, glass, carbon) and organic (PA, PAN, and other) fibers, commercial carbon, lamellar aluminum, kaolin, betonite, vermiculite, chalk, calcium silicate, mica, talc. 

Organic fibers (PA, PAN), glass fibers, graphite, coke, lamellar aluminum, asbestos, kaolin, vermiculite, mica, talc. 

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... 

Lamellar extenders improve coating properties, e.g., rheology (in particular thixotropy by talc and kaolin), matting (talc), dry hiding (talc, kaolin), and adhesion (talc, kaolin). 

Ferrage, E. Martin, F. Boudet, A. Petit, S. Fourty, G. Jouffret, F. Micoud, P. De Parseval, P. Salvi, S. Bourgerette, C. Ferret, J. Saint-Gerard, Y. Buratto, S. Fortune, J. (2002) Talc as Nucleating Agent of Polypropylene Morphology Induced by Lamellar Particles Addition and Interface Mineral-matrix Modelization. /. Mater. Sci. Vol.37, No.8, pp.1561-1573... 

Pure talcs of fine particle size and high lamellar structure, in combination with a new generation bromine compound, make it possible to obtain optimum mechanical properties and fire resistance as well as a limitation on the emission of corrosive by-products. Good results have been recorded with polyolefins in synergy with bromine compounds, for applications such as connectors and appliances. 

Examples of inert or extender fillers include china clay (kaolin), talc, and calcium carbonate. Calcinm carbonate is an important filler, with a particle size of about 1 pm. It is a natural product from sedimentary rocks and is separated into chalk, limestone, and marble. In some cases, the calcium carbonate may be treated to improve interaction with the thermoplastic. Glass spheres are also used as thermoplastic fillers. They may be either solid or hollow, depending on the particular application. Talc is a filler with a lamellar particle shape. It is a namral, hydrated magnesium silicate with good slip properties. Kaolin and mica are also natural materials with lamellar structures. Other fillers include woUastonite, silica, barium sulfate, and metal powders. Carbon black is used as a filler primarily in the rnbber industry, but it also finds application in thermoplastics for conductivity, for UV protection, and as a pigment. Fillers in fiber form are often used in thermoplastics. Types of fibers inclnde cotton, wood flour, fiberglass, and carbon. Table 1.3 shows the fillers and their forms. An overview of some typical fillers and their effect on properties is shown in Table 1.4. Considerable research interest exists for the incorporation of nanoscale fillers into polymers. This aspect will be discussed in later chapters. 

Mica flakes embedded in a polymer and properly oriented in a plane can provide a tortuous path to vapors and liquids, similarly to the natural composites shown in Figure 1.1. Barrier properties can be imparted in blow-molded containers, packaging films, and corrosion-resistant coatings not only by mica but also by other impermeable lamellar fillers, including glass flakes, talc, and nanoclays. In blown LDPE film, the addition of 10% mica was found to reduce the oxygen permeabihty from 4.16 to 3.03 Barrer [37]. Assuming an impermeable, fully oriented lamellar filler, Eq. (8.1), [38] maybe used to predict the composite permeability. Pc, perpendicularly to the filler plane as a function of the matrix permeability, P , filler volume fraction, V(, matrix volume fraction, V , and filler aspect ratio a... 

High aspect ratio fillers include wollastonite and talc, and mica, a lamellar or plate-like filler, also has a modest reinforcing effect. 

Calcium carbonate is an important filler with a particle size of about 1 p,m. It is a natural product from sedimentary rocks and is separated into chalk, limestone, and marble. In some cases the calcium carbonate may be treated to improve the bonding with the thermoplastic. Glass spheres are also used as thermoplastic fillers. They may be either solid or hollow, depending on the particular application. Talc is an important filler with a lamellar particle shape. It is a natural hydrated magnesium silicate with good slip properties. Kaolin and mica are also natural materials with lamellar stracture. Carbon black is used as a filler primarily in the rubber industry. 

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