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Effects of nanofiller concentration and surface treatments on the morphology, thermal, viscoelastic and mechanical behaviors of polypropylene copolymer (PP)/boehmite alumina (BA) nanocomposites were investigated. Both untreated and treated BA particles with octylsilane (OS) and with sulphonic acid compound (OS2) were added up to 10 wt% to produce nanocomposites by melt mixing followed by film blow molding and hot pressing. Dispersion of BA was studied by scanning electron microscopy. Differential scanning calorimetry and wide-angle X-ray scattering were adopted to detect changes in the crystalline structure of PP. Thermooxidative degradation of the nanocomposites was assessed by thermogravimetrical analysis. Dynamic mechanical analysis served for studying the viscoelastic, whereas quasi-static tensile, creep and Elmendorf tear tests were used to detect changes in the mechanical performance. BA nanoparticles were finely dispersed in PP up to 10 wt%, even when they were not surface modified. The resistance to thermal degradation was markedly improved by BA nanomodification. Changes observed in the mechanical properties were attributed to BA dispersion, filler/matrix interactions and related effects because the crystalline characteristics of the PP matrix practically did not change with BA modification.

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Trilayer low-density polyethylene (LDPE) films were prepared by incorporating varying concentrations of thyme oil, as the antifungal active additive for avocado packaging. A comprehensive thermal, structural, mechanical, and functional characterization of the prepared films was carried out. Thermal stability of the film reduced with the addition of thyme oil in higher concentration, whereas the degree of crystallinity increased upto 2.5 wt % thyme oil loading. The elastic modulus and elongation at break of the films decreased in presence of thyme oil. However, the incorporation of thyme oil did not change the water vapor transmission characteristics of the original film. The antifungal activity of the films was tested against Colletotrichum gloeosporioides causal organism of "anthracnose" postharvest disease in avocados. The results indicated that the films have great potential as antifungal packaging materials for avocado fruits.