Montmorillonite thermal degradation

Bourbigot, S., Gilman, J. W., and Wilkie, C. A. Kinetic analysis of the thermal degradation of polysty-rene-montmorillonite nanocomposite, Polym. Degrad. Stab. (2004), 84, 483 -92. 

Thermal degradation of chloromethyl-1,3,5-trioxanes 127 (Scheme 29) in the presence of catalytic amounts of montmorillonite clay generated a-chloroaldehydes which could be treated in situ with thiourea to afford 2-aminothi-azoles 128, or with ethylene glycol to yield the corresponding 2-chloromethyl-l,3-dioxolanes 129 <1994CL2039>. The acidic sites in montmorillonite clays may act as acid catalysts, though the details of the mechanism were not provided. 

Riva, A., Zanetti, M., BragUa, M., Camino, G., and Falqui, L. 2002. Thermal degradation and rheological behaviom- of EVA/montmorillonite nanocomposites. Polymer Degradation Stability 77 299-304. 

Carrasco, F., Pages, P. Thermal degradation and stability of epoxy nanocomposites influence of montmorillonite content and cure temperature. Polym. Degrad. Stab. 93, 1000 (2008)... 

Bmardic, I., Macan, J., Ivankovic, H., Ivankovic, M. Thermal degradation kinetics of epoxy/ organically modified montmorillonite nanocomposites. J. Appl. Polym. Sci. 107, 1932-1938 (2008)... 

Except montmorillonite, other clays like layered double hydroxide (LDH) can enhance thermal degradation of polymers. In such nanocomposites there are no reported for accelerating effect of LDH on polymer thermal degradation. This is because LDH can be more easily dispersed in intercalated or exfoliated structures, compared with MMT, into a polymer matrix and thus the stabilization effect is higher [22]. 

Authors have reported the thermal degradation behaviour of polycaprolactone (PCL) bio-nanocomposites [47, 77]. A study by Chrissafis et al. [46] investigated the thermal behaviour of modified and unmodified nanocomposites on PCL. They revealed that both unmodified montmorillonite and multiwalled carbon nanombes inhibited the thermal degradation of the bio-nanocomposites. On the other hand, organically modified montmorillonite and nanosilica increased the rate of degradation of PCL bio-nanocomposites (Fig. 9). 

Lately Qin at al. reported data on polypropylene/montmorillonite (PP/MMT) microcomposites thermal degradation and flammability [11]. They mentioned that PP microcomposites exhibit higher thermal stability and considerably reduced peak heat release rate due to physico-chemical adsorption of the volatile degradation products on the silicates... 

Natural rubber/cw-1,4-polybutadiene (NR/BR) blends (70/30 mass ratio) have been widely used in the tire industry. Many nanocomposites based on organo-montmorillonite (OMMT)/rubber blends have been investigated. However, relatively little attention had been paid to binary rubber hybrids/ montmorillonite nanocomposites, and according to Zheng Gu et ah, no studies existed dealing with OMMT/NR/BR nanocomposites. So, the authors described the preparation of OMMT/NR/BR nanocomposites by direct mechanical blending and determined the cure characteristics, static mechanical properties, dynamic mechanical properties, and thermal stability of the nanocomposites. OMMT/NR/BR nanocomposites had exactly the same onset decomposition temperature and lower thermal degradation rate as the NR/BR blends. 

Botana A, Mollo M, Eisenberg P, Torres Sanchez RM (2010) Effect of modified montmorillonite on biodegradable PHB nanocomposites. Appl Clay Sci 47(3 ) 263-270 Bruzaud S, Bourmaud A (2007) Thermal degradation and (nano)mechanical behavior of layered silicate reinforced poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanocomposites. Polym Test 26(5) 652-659... 

The improvement in the thermal performance of the polymers after the incorporation of filler was demonstrated in Figure 1.9 for poly(methyl methacrylate). Figure 1.14 further shows the thermal behavior of polypropylene nanocomposites containing different volume fractions of montmorillonite modified with dioctadecyldimethylammonium. Curve 1 represents the thermal degradation of pure polymer. Curve 2 represents the composite with 1 vol% clay. The thermal stability of the polymer was significantly enhanced. Further... 

Figure 1.17 Thermal degradation behavior of nanocomposites containing (a) quinohnium- and (b) pyridinium-modified montmorillonites in different amounts. Reproduced from [41] with permission from Elsevier.

If the concentration increased further, a third fraction of surfactant occurred that was weakly attached by van der Waals forces to a layer of sorbed surfactant cations and underwent thermal degradation at temperatures very similar to that for pure surfactant [95, 96]. Additionally, Osman et al. found that the thermal stability of alkylammonium self-assembled monolayers on montmorillonite, estimated by the time needed for 5% isothermal mass loss, was high enough to enable compounding it with several commercially available polymers [97]. 

A. Gu and G. Liang, Thermal degradation behaviour and kinetic analysis of epoxy/montmorillonite nanocomposites. Polymer Degradation and Stability, 80 (2003), 383-91. 

---