Characterisation of LDH-PE Materials

Other techniques also very valuable to determine the performance of the nanocomposites are those related to their applied properties, i. e., those studying the changes in the properties of the nanomaterials, the effect of different loadings of layered nanocharges on polyethylene properties, and the effect on their applications. Among these properties, the most relevant ones are the mechanical and thermal properties. 

A comparative study has been carried out by Manzi-Nshuti et al. [159] on the mechanical response of PE to which Zn, Mg, and Al hydroxides had been added and that shown by PE/Mg,Al LDH and PE/Zn,Al EDEI. The amormts of filler were chosen to have the same metal loadings in both cases (mixed hydroxides or EDffs fillers). The results evidenced a better behaviour of the samples with the layered filler. The samples with the hydroxides showed worse mechanical properties, probably due to a weaker interaction between the filler and the polymer. 

The relationships between the mechanical response and the morphology of the fillers are not easy to be correlated for polyethylene-layered com-pormds, and in some cases inconsistent results are found in the literature among different authors, although a direct relationship between the exfoHa-tion degree and the change in the mechanical response seems to exist. 

The chemical composition of the LDH also seems to have an effect on the mechanical response of the nanocomposite [159]. A PE/Zn,Al LDH nanocomposite showed an increase in the elongation at break when compared with the unloaded polymer. However, when Mg instead of Zn exists in the hydrotalcite layers of the PE/Mg,Al LDH, such a parameter largely decreases. The reason might be in the different dispersion degree. A PE/ Zn, Al LDH sample with 3% (w/w) loading shows a lower concentration of aggregates than the Mg sample with the same filler loading. 

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