Length scale at the glass transition in semi-crystalline compatibilized polylactide/clay nanocomposites

During the last ten years, great attention has been paid to the effects of interfaces and geometrical confinement on the molecular dynamics of polymers [1,2,3]. One of the characteristic parameters describing the glass transition is the cooperativity length which provides the average dimension of the alpha relaxation process. To investigate the cooperativity length from calorimetric measurements, the Donth's approach [4] is the most appropriated. Previous works have highlighted that interfacial interactions between amorphous polymer and exfoliated clays lead to a cooperativity length increase while confinement of polymer chains in the galleries of clays (intercalated nanocomposite) produces a strong reduction of cooperativity [5]. In this work we propose to investigate the nature of the polymer/clay interactions thanks to the cooperativity length determination in Polylactide-based nanocomposites with the presence of polybutyrate adipate terephthalate (PBAT) compatibilizer. Polylactide (PLA) is a semi-crystalline polymer which thermal crystallization can easily be tailored due to its slow kinetic, and can induce different crystalline forms ( and ) depending on the crystallization temperature [6,7], leading to strongly ordered or defective crystals. So this study aims at picturing the dissociated or cumulated impact of compatibilization and crystallization on the cooperativity in exfoliated and intercalated morphologies.