Effect Of Processing On Microstructure, Rheology And Properties Of Glass Fiber Reinforced Ternary Composites

Short glass fiber (SGF) is the most widely-used reforcing fibers in fiber reinforcedpolymer composites. The present work focuses on the relationships among processing, rheology,morphology, and mechanical properties of the SGF reinforced polymer composites using twodifferent composites, i.e.,(PA6/MMT)/SGF and PP/EPDM/SGF.The (PA6/MMT)/SGF composites were prepared using a twin-extruder. The parison wasformed using a single-screw extruder with different die geometries (divergent and straight die) andscrew speed (20,40,60and133rpm). At relatively high shear rates, both PA6/MMT and(PA6/MMT)/SGF composites show lower shear viscosities than that of pure PA6, due to thefact that MMT and SGF were oriented under shear. The η*, G’and G"of PA6weresignificantly increased with the addition of MMT and SGF. At the same time, the compositeswere transformed from elastic response dominated state to viscous response dominatedone.The SGF oriented along the flow direction within the parison wall formed by straight die,while that formed by divergent die showed five different orientation layers, that is, skinintermediate layer, sub-skin layer, core layer, core intermediate layer, inner layer, respectively.The SGF in the skin intermediate and inner layers oriented along the flow direction. Thedeviation between the orientation direction of SGF and melt flow direction occurred in thecore layer, the angle between the two directions increased with the screw speed. When thescrew speed increased from20to133rpm, the angle increased from45oto85o. Under theeffects of complex flow field, the network structure of the SGF formed in the sub-skin andcore intermediate layers.The compounding sequence can influence the morphology, rheological properties, andmechanical properties of the PP/EPDM/SGF composites. The SGF was encapsulated byEDPM, and the morphology of EDPM phase was mainly droplets and fibers in the(EPDM/SGF)/PP composite. The EDPM phase was mainly in the form of interconnectedlaminar morphology in (PP/SGF)/EPDM composite. For PP/EPDM/SGF composite, theEPDM phase mainly showed lamellar morphology, and also showed droplet morphology.PP/EPDM/SGF composite showed the highest G’and η*, whereas (EPDM/SGF)/PPcomposite showed the lowest ones.(PP/SGF)/EPDM composite showed the highest tensilestrength (22.32MPa) and impact strength (24.18kJ·m-2), due to the high interfacial strengthbetween PP and SGF and the formation of interconnected laminar morphology, respectively.