The Role of Oxidation in the Migration Mechanism of Layered Silicate in Polypropylene Nanocomposites
Mauro Zammarano, Jeffrey W. Gilman, Marc R. Nyden, Eli M. Pearce, Menachem Lewin
Polymer nanocomposites based on layered silicates (PLS) have attracted the interest of the scientific community for their outstanding combination of properties such as mechanical and chemical resistance, and reduced permeability and flammability. It is well demonstrated that heating induces structural changes in PLS which are depending on the nature of the atmosphere used during the thermal treatment. Recently, it was shown that heating can also determine a 3-4 fold increase of clay concentration on the surface of polypropylene/layered silicate nanocomposites, through a migration mechanism. Two causes for the migration of the clay particles to the surface were suggested for heating in the isothermal conditions. The first one is due to the gases and gas bubbles formed during the decomposition of the surfactant and the polymer which propel the clay particles to the surface. The second cause is thermodynamic. The clay migrates to the surface due to a difference in the interfacial tension between clay and polymer, and the surface free energy (SFE) of the polymer. In this work we perform different thermal treatments of polypropylene nanocomposites with both oxidative and inert atmosphere in order to investigate the role of oxidation in the migration mechanism. By understanding the mechanism of clay migration we can hope to alter the clay concentration on the surface of the nanocomposites by selecting proper processing conditions. This possibility may has important technological applications in flame retardancy and scratch resistance.
, Gilman, J.
, Nyden, M.
, Pearce, E.
and Lewin, M.
The Role of Oxidation in the Migration Mechanism of Layered Silicate in Polypropylene Nanocomposites, Macromolecular Rapid Communications
(Accessed February 27, 2024)