Silver nanoparticles in isotactic polypropylene (iPP) Part I. Silver nanoparticles as metallic nucleating agents for β-iPP polymorph

Isotactic polypropylene (iPP) nanocomposites containing 0.1, 0.2, 0.4 and 0.6 wt % of silver nanoparticles (nAg) were prepared by melt compounding in a one-screw extruder. Selected samples were isothermally recrystallized at different temperatures 50, 75, 100, 125, 130 and 135 degrees C, and under non-isothermal conditions. The size of the silver particles dispersed in the iPP matrix were estimated by ultraviolet/visible spectroscopy (UV-VIS). The effects of nAg additions on the structure of the iPP were studied by wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) techniques. The results clearly indicate that the addition of nAg induces the formation of the beta-iPP polymorph. It is shown that the relative amount of the beta form in the recrystallized nanocomposites depends on both the concentration of silver nanoparticles and thermal conditions of recrystallization.