Thermal degradation of polyethylene/layered double hydroxides nanocomposites

Abstract

Mg-Al layered double hydroxide (LDH) was modified with sodium dodecyl sulfate (SDS) by regeneration method. Polyethylene/modified LDH composites (PE/SDS-LDH) were prepared by melt blending and solution mixing method. Maleated polyethylene (PEgMA) was used to improve the compatibility between LDH and PE. The dispersion of LDHs in PE matrix was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). Thermal degradation of PE/SDS-LDH composites was characterized by thermogravimetric analysis (TGA). The results reveal that PE/PEgMA/SDS-LDHs microcomposites were obtained by melt blending method and PE/PEgMA/SDS-LDHs nanocomposites were prepared by melt blending PE with SDS-LDH/PEgMA master-batch obtained by solution mixing. Due to the thermal decomposition of LDHs at much lower temperature than PE, the degradation of composites begins at low temperature regardless of the dispersion of LDH in PE. The initial degradation temperature corresponding to 5% weight loss of nanocomposites is higher than that of microcomposites. Compared with microcomposites, the nanocomposites present the higher temperature corresponding to the maximum thermal degradation rate and more residues at the end of thermal degradation, indicating the better barrier properties and charring effects of nano-dispersed LDH.