Thermal stability of organoclay

Several research works reported that the thermal stability of organoclays increases with the number of long alkyl tails in the ammonium molecule (Figure 2.10) [40, 97]. 

The degradation and/or release of the intercalated surfactants in the galleries can promote the collapse of the interlayer spacing and changes in the surface characteristics. The thermal stability of organoclays depends on the type and concentration of surfactants and the interlayer structure [17]. 

Figure 3.6 shows the thermal stability of organoclay prepared with aminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) and cetylpyridinium chloride (CPC) [31]. 

Imidazolium surfactants have been used to enhance the thermal stability of organoclays. Trialkylimidazolium salt derivatives were prepared with propyl, butyl, decyl, and hexadecyl... 

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. 

Thermal analysis of hexadecyltrimethyl quaternary ammonium ion exchanged onto montmorillonite [9] indicates that water could be present in the quat-clay gallery up to 130°C. Reviews of published studies [3] of the thermal stability of organoclays indicate that water could be present up to 200°C. These studies indicate that the addition of quat to montmorillonite past the exchange capacity compromises the thermal stability of the organoclay. Removal of quat from montmorillonite by solvent... 

H. He, J. Duchet, J. Galy, and J.-F. Gerard. Influence of cationic surfactant removal on the thermal stability of organoclays. Journal of Colloid Interface Science, 295 (2006), 202-208. 

In the matrix of PLA/ polycaprilactone (PCL)/OMMT nano-composites, the silicate layers of the organoclay were intercalated and randomly distributed (Zhenyang et at, 2007). The PLA/PCL blend significantly improved the tensile and other mechanical properties by addition of OMMT. Thermal stability of PLA/PCL blends was also explicitly improved when the OMMT content is less than 5%wt. Preparation of PLA/thermoplastic starch/MMT nano-composites have been investigated and the products have been characterized using X-Ray diffraction, transmission electron microscopy and tensile measurements. The results show improvement in the tensile and modulus, and reduction in fracture toughness (Arroyo et ah, 2010). 

Measures have been taken to improve the thermal stability of the organoclays. Extraction of excess modifier can improve the thermal stability of alkyl ammoniums, sometimes with improvements up... 

Following obtained data authors draw the conclusion that the optimal results for thermal properties ate being obtained if 2 wt% of the organoclay is added [11,12,19], The great number of studies on the polymeric composite organoclay-based materials show [11-13,19] that the inclusion of the inoiganic component into the organic polymer improves the thermal stability of the latter, see Tables 3 and 4. 

PP nanocomposite toughened with poly (ethylene-co-octene) using PP-g-MAH (6 wt%) as compatibilizer Thermal stability of the rubber-toughened PP nanocomposites was studied Thermal stability was improved significantly with the addition of small amount of organoclay Lim et al. 2006... 

PBT/HDPE PBT 1 to 90 wt% Nanofil 919 PBT phase and interface based on blend composition The MMT particles located at the blend interface reduce the interfacial tension between blend components. The addition of organoclay also increases the thermal stabilization of blend morphology Hong et al. 2006a, b... 

Shojaei and Faghihi [20] studied the effect of different concentrations of organoclay on styrene-butadiene mbber and phenolic resin blends prepared by two-roll mill. Thermogravimetric studies indicated that the organoclay enhanced the thermal stability of styrene-butadiene rubber vulcanizate, whilst manifesting a catalytic behavior in presence of the phenolic resin. 

Wong et al. [41] showed that sodium montmorillonite imparted a better thermal stability to polyvinylidene difluoride-polyethylene (PE) glycol polymers than did organic montmorillonite. They showed that ethyl-3-methylimidazolium tetrafluoro-borate-functionalized montmorillonite greatly enhanced the thermal stability of the polymer. Liu et al. [42] studied the effect of various organoclays on the heat stability of poly trimethylene terephthalate. 

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