New Reactive Formulations For Polypropylene Foams

摘要

This work focuses on reactive extrusion to design polypropylene (PP) chains with long and short branching to obtain non-linear behavior for the synthesis of low-density foams (<100 kg m~(?3)) using a batch supercritical carbon dioxide (scCO_2) foaming process. From a maleic anhydride (MA) grafted PP (PP-g-MA), the long-branched chains are performed using MA/ OH reaction (with Sorbitol alcohol). On the other hand, short branched chains are made from the hydrolysis/condensation of amino-alkoxysilane (3-Aminopropyl-triethoxysilane, APTES) in situ grafted onto PP chains through the (MA/NH2 reaction). The results show the need to combine both systems to reach the optimum of the rheological behavior (linear and non-linear) to obtain a low-density foam. On the other hand, the foaming behavior of polypropylene/polyamide 6 (PP/PA6) polymer blends at T = 180 ℃ is also investigated as another way to control the rheology and foamy behavior. At this temperature, T = 180 ℃, the PA6 phase behaves as solid dispersed particles in a viscoelastic liquid PP matrix. Finally, this study shows the influence of PA6 concentration on the foaming and foam morphology correlated to a rheological study (shear and extensional) and mechanical compressive properties.