Properties of OMt PE CPN

PE is a polymer with a high stability which decomposes in a single step under pyrolytic conditions with a peak temperature around 475 C under dynamic heating. In the presence of the nanoclay the results reported by the different authors are quite misleading. Most authors describe no effect of the Mt on the thermal stability of PE composites and nanocomposites, but there are others who describe an increase or decrease in the stability. Anyhow, the described shifts in the thermal decomposition temperature are small and may depend on different factors, especially on the intrinsic stability of the modifying agent of the nanoclay. 

Accordingly Moraviec et al. (2005) also described no increase in the thermal stability of LDPE independently if the nanoclay underwent exfoliation or not. These authors described an improved thermal stability of the compatibilized composites in air. Sanchez-Valdes etal. [18] also found that the exfoliated or intercalated clay inhibited the polymer decomposition in air, which were justified by the improved barrier for diffusion of oxygen into the material and also by the diffusion of the degradation by-products from the sample. 

On the other hand, Zhai et al. [35] described a small increase in the decomposition temperature at the earlier stages of the decomposition process for OMt PE CPN containing 3 and 5 phr of OMt modified with an ammonium salt (with a C-18 tallow), but the highest increase in the thermal stability was found for the CPN containing 1 phr of OMt, which was justified by a highest exfoliation degree and which kept monolayer in the composite containing Iphr of OMt. By other hand EM et al. [41] described an important improvement of the thermal stability of OMt PE CPN when OMt was modified with imidazolium and phosphonium salts due to the intrinsic stability of these salts as compared to conventional ammonium salts. 

The type of surfactant employed to promote the clay layers separation could also affect strongly to the mechanical behaviour. Livi et al. [41] employed imidazolium and phosphonium-modified montmorillonites, and found with these surfactants an important increase in stiffness of the PE without reducing its fracture behaviour. For example the moduli could be increased by 50% with 2wt% of the imwashed phosphonium OMt. 

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