Antioxidant intercalated Zn-containing layered double hydroxides: preparation, performance and migration properties

Abstract

A straightforward preparation of the antioxidant anion 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (DBHP), intercalated into layered double hydroxides (DBHP-LDH) via a co-precipitation method, and adjusting the (Mg, Zn, Al) metal ratio was reported. The influence of the Zn-containing LDH composition was studied by measuring the thermal stability and the DBHP anti-migration ability when dispersed into polypropylene (PP). The overall crystallinity of α-PP is found to remain similar with the dispersion of DBHP-LDH particles, but shaper diffraction peaks indicate the presence of larger crystallized domains, most probably arising from an anisotropic connection of smaller coherent PP domains with the help of PP chains diffusing inside the layered inorganic structure. The latter is acting as a coalescent agent yielding an intercalated PP nanocomposite structure with extended interfaces inducing a shift in the glass transition temperature to a higher temperature. The radical-scavenging activity of DBHP when interleaved between LDH layers is found to be conserved while an optimized cation composition for MgZnAl–DBHP is found for the thermo-oxidative stability in association with a lower DBHP migration among the PP nanocomposite series, making the resulting PP nanocomposite a highly promising candidate for possible applications.