Spherulite growth rates of in situ prepared poly(propylene terephthalate)/SiO2 nanocomposites

The spherulite growth rates of in situ prepared PPT/SiO₂ nanocomposites containing 2–5 wt% nano-silica were studied. Measurements of the spherulite growth rates were carried out by applying non-isothermal experiments using polarized light microscopy (PLM). Comparison with results from isothermal PLM tests showed good agreement. Isothermal crystallizations after self-nucleation were also performed using differential scanning calorimetry (DSC) and the inverse crystallization half-times were estimated. The Lauritzen–Hoffman analysis was applied by using data from both isothermal and non-isothermal PLM experiments and the DSC results. Regimes II–III transition were observed at critical breakpoint close to 195 °C. The regimes I–II transition was not so clear, because of the semi-rigid macromolecular chains of the polymers. Results using DSC data were in satisfactory agreement to those using PLM spherulite growth data.