Investigation of mechanical, dynamic mechanical, rheological and morphological properties of blends based on polypropylene (PP) and cyclic olefin copolymer (COC)

In this study, polypropylene (PP)/cyclic olefin copolymer (COC) blends were processed in a co-rotating twin screw extruder by melt processing technique. PP/COC blends were prepared without compatibilizer as COC is expected to be compatible with polypropylene due to its olefinic behaviour. Effects of COC blending with PP on mechanical, dynamic mechanical, rheological and morphological behaviour were investigated thoroughly. An increasing fraction of stiffened COC in the PP/COC blends is responsible for the enhancement of tensile strength and modulus, flexural strength and modulus and of a decrease in the elongation at break and impact energy. Various blend system models, such as Parallel, Series, Coran, Takayanagi, Kerner and Halpin Tsai models, have been used to predict tensile strength and modulus and compared with experimental data. When COC is added, shear viscosity of PP/COC blends increases compared to pure PP. The high shear rheological behaviour of PP/COC blends displayed non-Newtonian and shear-thinning behaviour. Shear viscosity as functions of blend composition shows negative deviation from the expected log linearity. DMA results established immiscibility of PP and COC in the blend system, by providing independent glass transition (Tg) for PP and COC component. Scanning electron microscopy results revealed fibrillar morphology for PP/COC blends and co-continuous behaviour in the PP50/COC50 blend composition. The intention of the prepared PP/COC blends is to enhance ...

Source: European Polymer Journal - September 18, 2018 Category: Chemistry Source Type: research