Effects of extruder parameters and silica on physico-mechanical and foaming properties of PP/wood-fiber composites

In this study, the effects of screw configuration, screw speed and silica content on the physico-mechanical and foaming properties of PP/wood-fiber (WF) composites were investigated. PP/WF composites were produced by the intermeshing co-rotating twin screw extruder. Microcellular closed cell PP/WF composite foams were prepared using pressure-quench batch process method. Firstly, an attempt has been made to determine the optimum conditions of extrusion that involve screw configurations and screw speed. The mechanical properties and morphology results showed that PP/WF composite prepared under the configuration C at screw speed of 150 rpm have higher mechanical properties, and narrower cell size distribution caused by uniform dispersion of wood fiber. And then, under the optimal processing conditions, the effect of silica content on the physico-mechanical properties of PP/WF composite, the final cell morphology as well as the relative density of the foamed PP/WF/Silica composites is studied.