Polystyrene/CaCO3 Composites With Different CaCO3 Radius and Different Nano-CaCO3 Content-Structure and Properties

The Archimedes' principle and physical theory are attempted to analysis the densification and structure of the polystyrene (PS) composites by melt compounding with CaCO3 having different particle size. The difference between the measured specific volume (nu) and the theoretically calculated specific volume (nu(mix)), Delta nu = nu-nu(mix), can reflect the densification of the composites. It is clearly demonstrated that the PS composites become more condensed with the reduction of the CaCO3 particle size. Especially, when the content for nano-CaCO3 achieves 2 wt%, the Delta nu value of the composites reaches the least, which shows the best densification. Meanwhile, the glass transition temperature (T-g) reaches the maximum value of about 100 degrees C by differential scanning calorimetry (DSC) and thermal mechanical analysis (TMA), which indirectly reveals the composites microstructure more condensed. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal that 2 wt% nano-CaCO3 uniformly disperses in PS composites. The CaCO3 selected in this experiment has certain toughening effect on PS. The impact and tensile strength increase with addition of nano-CaCO3, but the elongation at break decreases. When nano-CaCO3 content achieved 2 wt%, the impact and tensile strength present the maximum value of 1.63 KJ/m(2) and 44.5 MPa, which is higher than the pure PS and the composites filled with the same content of micro-CaCO3. POLYM. COMPOS., 31:1258-1264, 2010. (C) 2009 Society of Plastics Engineers