Thermal Stability and Combustion Behavior

In air a thermooxidative mechanism of degradation leads to a higher amount of poly aromatic structures up to about 500°C. However, at higher temperatures, complete volatilization of material occurs, and no residue is observed. 

2 Thermal Decomposition of Organically Modified Layered Silicates The thermal stability of organically modified clays plays a key role in the synthesis and processing of polymer-layered silicate (PLS) nanocomposites. The thermal decomposition of ammonium-treated clays proceeds, schematically, in four steps  

Evolution of absorbed water and gaseous species below 180°C 

Evolution of products associated with residual organic carbonaceous residue between 700 and 1000°C 

The onset temperature of decomposition of alkyl quaternary ammonium-modified montmorillonite, in nonoxidative thermal degradation, is about 180°C. Initial degradation of the surfactant follows either a Hoftnann elimination or an Sn2 nucleophilic substitution mechanism. Both mechanisms can affect the performance of high-processing-temperature nanocomposites and, in general, the thermal stability and combustion behavior of nanocomposites. In particular, Hofmann elimination generates acidic sites on the layered silicate that can act as a protonic acid catalyst on polymer decomposition. Imidazolium and phosphonium salts exhibit improved thermal stability compared to ammonium salts.Alkylimidazolium salt-modified layered silicates were used successfully to prepare organoclays that exhibit an onset of decomposition temperature up to 392°C. 

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H. Ma, Z. Fang, and L. Tong. Preferential melt intercalation of clay in ABS/ brominated epoxy resin-antimony oxide (BER-AO) nanocomposites and its S5mergistic effect on thermal degradation and combustion behavior. Polymer Degradation and Stability, 91 (2006), 1972-1979. 

J.C. Oxley, J.L. Smith, E. Rogers, W. Ye, A. Aradi, T. Henley, Heat-Release Behavior of Fuel Combustion Additives, Energy and Fuel, 5 (2001) 1194-1199. J.C. Oxley, J.L. Smith, E. Rogers, W. Ye, A. Aradi, T. Henley, Fuel Combustion Additives A Study of their Thermal Stabilities and Decomposition Pathways, Energy and Fuel, 14(6) (2000) 1252-1264. 

The degradation and combustion behavior of polycarbonate/POSS hybrid system has been reported recently.48 Different loading contents of trisilanolphenyl-POSS (TPOSS) were melt blended with polycarbonate matrix (PC). The data shown in Table 8.4 indicate that no improvement in thermal stability parameters (i.e., onset decomposition temperature and peak decomposition temperature) was observed compared to the neat polycarbonate. The thermo-oxidative degradation process of the hybrid system proved to be a complicated process, which includes hydrolysis/alcoholysis of the carbonate linkage, free radical oxidative chain degradation, reformation, and branching and cross-linking reactions. 

Shao, C., Huang, J., Chen, G., Yeh, J., and Chen, J. Thermal and combustion behaviors of aqueous-based polyurethane system with phosphorus and nitrogen containing curing agent. Polymer Degradation and Stability, 65, 359-371 (1999). 

The impact of the nanocomposite technology on polymers is huge, reflected in enhanced properties of the resulting PNs, such as enhanced mechanical, barrier, solvent-resistant, and ablation properties.12 The effect of nanocomposite technology on the thermal and fire performance of the polymers is primarily observed in two important parameters of the polymers (1) the onset temperature (7( ,nsct) in the thermogravimetric analysis (TGA) curve—representative of the thermal stability of the polymer, and (2) the peak heat release rate (peak HRR) in cone calorimetric analysis (CCA)—a reflection of the combustion behavior (the flammability) of the polymer. The Tonset will be increased and the peak HRR will be reduced for a variety of polymers when nanoscale dispersion of the nanoadditive is achieved in the polymer matrix. 

The impact of nanocomposite technology on flame retardance (the thermal and fire resistance) of the polymers, as mentioned in Section 11.1, is primarily reflected in two important parameters (1) the ronset in the TGA curve—representative of the thermal stability of the polymer and (2) the peak HRR in the curve of CCA—reflection of the combustion behavior (the flammability) of the... 

Many studies aimed to the formulation of post-combustion catalysts with higher OSC. Ceria proved to be a good candidate as a TWC support with enlarged OSC and satisfactory behavior under dynamic conditions [1,3-7] but a poor thermal stability. 

Zhan, J., Song, L., Nie, S., Hu, Y., 2009. Combustion properties and thermal degradation behavior of polylactide with an effective intumescent flame retardant. Polym. Degrad. Stabil. 94, 291—296. 

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