Nanofilled and/or toughened POM composites produced by water-mediated melt compounding: Structure and mechanical properties

Binary and ternary composites composed of polyoxymethylene (POM), polyurethane (PU) and synthetic boehmite alumina (AlO(OH)) were produced by water-mediated melt compounding technique. PU latex and/or aqueous alumina suspension were injected into the molten POM in a twin-screw extruder to prepare toughened and/or reinforced polymer composites. The dispersion of the alumina and PU was studied by transmission- and scanning electron microcopy techniques (TEM and SEM, respectively), and discussed. The crystallization of the POM-based systems was inspected by polarized optical microscopy (PLM). The mechanical and thermomechanical properties of the composites were determined in dynamic-mechanical thermal analysis (DMTA), short-time creep tests (performed at various temperatures), uniaxial static tensile and notched Charpy impact tests. Incorporation of alumina increased the stiffness and resistance to creep and reduced the tensile strength, elongation at break and impact toughness. The change in the above parameters was opposite for the POM/PU binary blends. Additional incorporation of alumina in the POM/PU blend enhanced the resistance to creep, elongation at break and maintained the impact toughness compared to the POM/PU blend.