Study On Morphology And Properties Of PS/SEBS/nano-TiO2ternary Composites

Polystyrene (PS) has been widely used in many fields because of its advantages suchas stiffness, transparency, process easily, moderate price and so on. However, the shortagesof PS are brittleness and low impact strenghth. PS was modified with SEBS and nano-TiO2synergistically in this paper. The morphology and properties of PS/SEBS/nano-TiO2composites were investigated. PS ternary composites with strength and toughness wereexpected to obtain.The morphology structure of PS composites was observed on scanning electronmicroscope. The elastomer average particle size and particle size distribution were carriedout using Nano Measurer1.2image analysis software. The mechanical properties, thermalstability, rheological properties, melt index were investigated with impact testing machine,electronic universal testing machine, DSC, torque rheometer and melt flow rate machine.The toughening mechanism of PS filled with elastomers and nano-TiO2ternary compositeswas analyzed and discussed. The results show that:The average particle size of dispersed phase SEBS particles increases with increasingSEBS concentration between0.6μm and1.4μm and particle size distribution of SEBSbecomes narrower gradually in PS/SEBS/nano-TiO2composites. The average particle sizeof SEBS decreases firstly and then increases with nano-TiO2concentration increased.The dispersed phase SEBS-g-MAH in PS/SEBS-g-MAH/nano-TiO2compositesshows a lower average particle size as compared to PS/SEBS/nano-TiO2composites and isunder0.5μm. PS/SEBS-g-MAH/nano-TiO2composites has lower decreasing rate of tensilestrength and higher notched impact strength than PS/SEBS/nano-TiO2composites. At16%elastomer concentration, the notched impact strength of PS/SEBS-g-MAH/nano-TiO2composites is20%higher than that of PS/SEBS/nano-TiO2composites. From theobservation of impact fracture surface, it is found that SEBS-g-MAH particles dispersemuch finer and more uniform in PS than SEBS particles. It indicates that the effectivenessof SEBS-g-MAH particles as toughening agent improves.The average particle size of SEBS in PS composites prepared by two-step is smalleras a whole than that of PS composites prepared by one-step at same nano-TiO2content.The toughening effectiveness of PS composites prepared by two-step is obvious. Whereasthe tensile strength of PS composites prepared by two-step decreases.The thermal stability and rheological properties of PS ternary composites areimproved. The glass transition temperature of PS/SEBS/nano-TiO2composites is higherthan pure PS. The toughening effectiveness of PS/SEBS/nano-TiO2composites is notsimple independent toughening addition but synergistic toughening effectiveness.