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The objective of this study was to prepare linear low density polyethylene (LLDPE)/chitosan/closite nanocomposites by using various concentrations of LLDPE, chitosan, and closite clay mineral. The nanocomposites were then characterized for their thermal, mechanical, and rheological properties by using different analytical techniques including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheological characterization, tensile strength study, and scanning electron microscopy. The TGA demonstrated that crosslinked composites are thermally more stable than non-crosslinked composites. The DSC stated that the percentage crystallinity of crosslinked composites is lower than the non-crosslinked composites. It is also observed that the increasing quantity of chitosan and closite also reduces the percentage crystallinity of the prepared nanocomposites. Rheological characterization revealed that, crosslinked composites are viscoelastic in nature and have high complex viscosities (η*) and high dynamic shear storage modulus (G′), while non-crosslinked composites showed high dynamic shear loss modulus (G″). Tensile strength of crosslinked composites was much higher than non-crosslinked composites, however elongation at break (Eb) values of non-crosslinked composites are higher than crosslinked composites. The scanning electron microscopy displayed strong adhesion between matrix-filler-interphase in crosslinked composites, while some gaps were also observed in non-crosslinked composites. As a conclusion, chitosan, closite clay, and the LLDPE based nanocomposites with improved thermal, mechanical, and rheological properties can be successfully prepared by employing a peroxide-initiated melt compounding technique. [ABSTRACT FROM AUTHOR]

Goldnanoparticle–porphyrin assemblies were formed by bindingfunctionalized porphyrins to gold nanoparticles (Au-NPs). Spectroscopicproperties of hybrids and binding strength of porphyrins to Au-NPswere observed based on number and type of linker moieties using fluorescencespectroscopy. Binding appears to be dependent on number rather thantype of linker moieties present on the porphyrin molecules, as tetraaminophenylporphyrin shows the highest binding among the molecules we studiedand causes agglomeration of nanoparticles due to presence of fourlinker groups. The inner filter effects of Au-NPs are considerablyhigh due to their high extinction coefficient and cause large errorsin the evaluation of quenching efficiencies. We have described a verysimple method to calculate the inner filter effects of Au-NPs by firstloading them with porphyrins and then replacing them with nonfluorescentligands. The difference in the fluorescence of unbound porphyrinsin the presence and absence of Au-NPs describes their inner filtereffects. [ABSTRACT FROM AUTHOR]