Effects of silicalite-1 nanoparticles on rheological and physical properties of HDPE

The addition of silicalite-1 nanoparticles (0.2-20 wt%) increased slightly the crystallization temperature of HDPE with silicalite-1 content, at 20 wt% loading by ca. 2.5 °C, but it had little effect on the melting temperature. The nanocomposites displayed a little higher onset degradation temperature than pure polymer by 7-11 °C. The WAXD profiles showed that the intensity of diffraction peaks for HDPE was decreased with increasing silicalite-1 content from 5 wt% but that the peak position of every crystal plane did not shift in the presence of silicalite-1 nanoparticles. The incorporation of the nanoparticles increased the melt viscosity of HDPE with silicalite-1 content. It also increased both storage (G′) and loss modulus (G″). In the so-called Cole-Cole plot, pure HDPE showed a single master curve whose slope was 1.37, while the nanocomposites with 10 and 20 wt% silicalite-1 exhibited the inflection in the low frequency range before which the slopes were 1.22 and 1.02, respectively. Much more accelerated crystallization behavior under shear was observed with silicalite-1 content at the isothermal crystallization temperature of 125 °C than at 120 °C.