Polyolefin nanocomposites prepared by melt compounding in a twin-screw extruder

In this work two types of fillers were used: organically modified montmorillonite and layered double hydroxide, organo-MMT and organo-LDH, respectively. The attention was focused on the selection of a correct mixing protocol (processing parameters such as mean residence time, screw speed etc.) in order to promote both high shear stress and high shear rate, thus assisting the filler dispersion. In particular, LDPE/organo-MMT and LDPE/organo-LDH nanocomposites were prepared via direct melt mixing in a co-rotating twin-screw extruder. A compatibilizer was also used for improving interactions between the clay and the polyolefin matrix. The morphology of nanocomposites was analyzed by X-ray diffraction (XRD) and by transmission electron microscopy (TEM). Moreover, in order to evaluate the degree of processability, the steady shear response at high shear flow conditions was investigated with an on-line capillary rheometer.