Perkalite as an innovative filler for isotactic polypropylene-based nanocomposites

Perkalite, an organically modified synthetic layered double hydroxide, was used as a filler in the preparation of nanocomposites based on isotactic polypropylene. The polymorphism of the polymer matrix was investigated, finding that Perkalite favors beta phase in certain conditions and is not a nucleant for the gamma polymorph. Perkalite promoted the formation of a dual population of lamellae, as evidenced by SAXS data. The dispersion of the filler was studied by WAXD, SAXS, and TEM. Perkalite was intercalated by the polymer and formed small, rather disordered tactoids, that determined an increase in physical mechanical properties, such as modulus, impact strength, thermal stability and heat deflection temperature. The Tm(0) of the materials was calculated by the method proposed by Marand, the kinetics of crystallization was evaluated by the Avrami analysis and also the Hoffman-Lauritzen theory of crystallization regimes was applied. Perkalite was found to depress Tm(0), to greatly enhance the rate of crystallization and to ease the chain folding of macromolecules.