Joint effects of rotational extrusion and TiO2 on performance and antimicrobial properties of extruded polypropylene copolymer pipes

摘要

In this study, effects of titanium dioxide (TiO2) and rotation extrusion on structures and properties of polypropylene random copolymer (PPR) pipes were investigated. The experimental results showed that with the presence of TiO2, not only the antibacterial ability of PPR pipe was improved significantly but also the toughness was enhanced since a large number of PP chains were promoted to crystallize into b-form crystals. Furthermore, when rotation extrusion was introduced into the process of PPR pipe, the drag hoop flow caused by mandrel and die rotation was superposed on the axial flow, so the polymer melts in the annulus underwent a helical flow and its flow direction deviated from the axis to drive the molecular orientation off the axial direction, bringing out the increased hoop strength. As a result, PPR pipe with excellent performance was prepared under the combined effect of rotation extrusion and TiO2. The antibacterial activity was 99.2%, the hoop tensile strength reached 27.5 MPa, 67.7% higher than that of the convention-extruded PPR pipe with TiO2, and the impact strength was 10.9 kJ/m(2), increased by 81.6% compared to that of the rotation-extruded pure PPR pipe. (C) 2015 Wiley Periodicals, Inc.