Montmorillonite organomodified

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. 

FIGURE 10.14 Compression force versus gap of EVA/PA6/APP-based intumescent formulations measured at400°C without (REF) and with nanoparticles (Si02, silica OMMT, organomodified montmorillonite LDH, lamellar double hydroxide). 

The FR properties of polymer-layered silicate nanocomposites have been studied for a wide range of polymers, especially for organomodified montmorillonites (OMMT) in thermoplastics. Depending on the nature of the polymer, the decomposition pathway and decomposition products may change.8 A major consequence of the introduction of modified clays is the formation or the enhancement of charred structure, caused by cross-linking processes possibly catalyzed by the nanoparticles. 

B. Swoboda, E. Leroy, F. Laoutid, and J.M. Lopez-Cuesta, Flame retardant PET/PC blends compatibilized by organomodified montmorillonites, Proceedings of the ACS Conference, New Orleans, LA, 2008. 

Some physieal-mechanieal properties of nanocomposites produced by in situ method, and also produeed via melt blending polyethyleneterephthalate with organomodified montmorillonite (nalchikit-M), educed from bentonite clay of Gerpegezh field (Russia, KBR) and from eommercial clay bentonite-128. 

The addition of plasticizer used for the improvement of mechanical properties leads generally to an increase in the oxygen permeability coefficient due to the higher mobility of the polymer chain and higher free volume [102]. On the contrary, the dispersion of nanoclays in PLA makes it possible to divide the permeability coefficient by 2 or 3 depending upon the type of the nanoclays (e.g. organomodified montmorillonite, cloisite 25A or 30B, organomodified synthetic fluorine mica) and exfoliation [129-131]. 

In this chapter we have divided modified clays in two different types namely organomodified montmorillonite (OMt) and expanded organo-montmorillonite (EOMt). The effect of these clay particles in NR matrix will be discussed elaborately in the forthcoming section. 

The most common usage concerns organomodified Montmorillonite (MMT), a natural phyUosiUcate extracted from Bentonite. Raw formula of Montmorillonite is (Na,Ca)o,3(Al, Mg)2Si40io(OH)2,nH20. 

Two types of MMT-sodium montmorillonite (Cloisite Na, Southern Clay) and an organomodified montmorillonite (Cloisite 30B) -were used to prepare MMT-PFA nanocomposites, denoted as NaMMT-PFA and 30BMMT-PFA, respectively. 

Figure 14.6 Formation of covalent bonds between 1,6-diisocyanatohexane and the silanol and hydroxyl groups in an organomodified montmorillonite as explained in Ref [70].

Nanocomposites of organomodified montmorillonites (C20A, C25A, and C30B) and a biodegradable PEA were obtained by in-situ polycondensation of sodium chloroacetylaminohexanoate [75]. This synthesis was based on a thermal polycondensation reaction in which the formation of a metal halide salt became the driving force of the process [76, 77]. 

The above technique can be advantageously adapted to a situation where the polymer of interest is not soluble in any solvent, as is the case for polyimides. The polyimide precursor, ie, a poly(amic acid) solution in dimethylacetamide, is prepared and blended to a dispersion of an organomodified montmorillonite in the same solvent. Dimethylacetamide is then gradually removed, and upon heating the poly(amic acid) film at 300°C imder nitrogen atmosphere the polyimide-clay hybrid is obtained. When an ammonium salt of dodecylamine is used in the ion-exchange process, true exfoliation is achieved and fiirthermore the clay platelets align parallel to the film surface (28). 

G. Liu, L. Zhang, D. Zhao, and X. Qu, Bulk polymerization of styrene in the presence of organomodified montmorillonite. Journal of Applied Polymer Science, 96 (2005), 1146-52. 

Carli, L.N., Crespo, J.S., Mauler, R.S., 2011. PHBV nanocomposites based on organomodified montmorillonite and haUoysite the effect of clay t5fpe on the morphology and thermal and mechanical properties. Composites Part A Applied Science and Manufacturing 42, 1601-1608. 

Figure 4.1 Diffraction pattern of an organomodified montmorillonite. The black arrow shows the (001) basal peak, the gray arrow points to a (hkO) peak.

Maspoch et al. [209] added organomodified montmorillonite to poly(ethylene-vinyl alcohol) (EVOH), studying the fracture behavior of 400 [xm thick cast films. The presence of the montmorillonite particles promoted an increase in... 

Bala, P., et al, Organomodified montmorillonite as filler in natural and synthetic rubber. Journal of Applied Polymer Science, 2004. 92(6) 3583-3592. 

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