Octamethyl-POSS-HDPE nanocomposites were prepared by the melt mixing route. The rheological and viscoelastic behavior of HDPE-octamethyl-POSS nanocomposites was investigated with a strain-controlled rheometer and dynamic mechanical analysis (DMA). The rheological results show that while at lower filler concentration (0.25-0.5 wt %) POSS particles act as lubricant and reduce the complex viscosity of the nanocomposites, at higher concentrations, viscosity increases. POSS remains miscible in HDPE at lower concentrations and lower temperatures used in the study; however it starts aggregating at higher concentrations and higher temperatures. The presence of POSS particles causes gelation in HDPE matrix at concentrations higher than 5 wt % possibly due to the segregated particle-particle interaction. The storage modulus shows an increase at lower POSS concentrations but decreases at higher POSS concentrations. The R-transition temperatures shift to higher values at low POSS concentrations and is attributed to restriction of the movement of HDPE chain segments in the intercrystalline regions due to the presence of POSS macromers around the crystallite boundaries. The effect of POSS on morphology of HDPE was studied with X-ray diffraction and DSC techniques. It was observed that while POSS does not interfere with the crystallization of HDPE, it crystallizes itself into nanocrystals.

ABSTRACT:In the present study isotactic polypropylene (PP) and metallocene-catalyzed linear low-density polyethylene (mLLDPE) were blended together to obtain thermoplastic materials (compositions) with improved toughness. Structure-property relationships were determined for these compositions with the help of scanning electron microscopy (SEM). Special emphasis was made on tracing the morphological features that led to the optimum mechanical performance. A co-continuous type of structure was found to have much superior toughness as compared to a dispersed-matrix structural type, for blends comprised of the same components (PP and mLLDPE). The study showed the fascinating possibility of creating toughened PP blends by inducing a co-continuous structure.

The present study investigated mixed polyolefin compositions with the major component being a post‐consumer, milk bottle grade high‐density polyethylene (HDPE) for use in large‐scale injection moldings. Both rheological and mechanical properties of the developed blends are benchmarked against those shown by a currently used HDPE injection molding grade, in order to find a potential composition for its replacement. Possibility of such replacement via modification of recycled high‐density polyethylene (reHDPE) by low‐density polyethylene (LDPE) and linear‐low‐density polyethylene (LLDPE) is discussed. Overall, mechanical and rheological data showed that LDPE is a better modifier for reHDPE than LLDPE. Mechanical properties of reHDPE/LLDPE blends were lower than additive, thus demonstrating the lack of compatibility between the blend components in the solid state. Mechanical properties of reHDPE/LDPE blends were either equal to or higher than calculated from linear additivity. Capillary rheological measurements showed that values of apparent viscosity for LLDPE blends were very similar to those of the more viscous parent in the blend, whereas apparent viscosities of reHDPE/LDPE blends depended neither on concentration nor on type (viscosity) of LDPE. Further rheological and thermal studies on reHDPE/LDPE blends indicated that the blend constituents were partially miscible in the melt and cocrystallized in the solid state.