Dynamic mechanic and creep behaviors of polyoxymethylene/boehmite alumina nanocomposites produced by water-mediated compounding

Abstract

Nanocomposites composed of polyoxymethylene (POM) and synthetic boehmite alumina (BA) are produced by water-mediated (WM) technique. According to WM technique, an aqueous BA 25 and BA 220 nm dispersion was injected into the molten POM in a twin-screw extruder to prepare the related nanocomposite with 3 wt% BA content. The dispersion of BA was studied by scanning electron microscopy and transmission electron microscopy. The thermal, mechanical and creep properties of the composites were determined in dynamic mechanical thermal analysis and short-time creep tests, respectively (performed at various temperatures). The data indicate that an improvement in the stiffness of nanocomposites can be achieved. The POM/BA 25 nm composite outperformed the POM and POM/BA 220 nm composite with respect to the storage modulus and creep characteristics. This was attributed to the particle size effect of BA. Master curves of storage modulus versus frequency and creep compliance versus time were constructed by applying the time–temperature superposition principle. It was established that the Burgers model and the Findley power law are fairly applicable to the creep compliance results.