Pectin-organophilized ZnO nanoparticles as sustainable fillers for high-density polyethylene composites.

A series of nanocomposites made of high-density polyethylene (HDPE) and 10 wt% zinc oxide nanoparticles (ZnO NPs) were produced by extrusion and injection molding. The nanoparticles were prepared via a green way using the pectin-based banana peel extract as the stabilizer and a proper dispersion-providing agent. The fillers were well-dispersed in the matrix and the composites exhibited improved functional characteristics such as increased thermal stability and mechanical properties. The presence of the pectin-organophilized filler had a significant impact on the crystallization process of HDPE. The kinetics of the degradation process was also altered in comparison to the pure polymer. The fire properties of the composites were enhanced as the amount of the gas products produced during their degradation was reduced, what was confirmed by thermogravimetric analysis coupled with gas products analyses (TGA/FTIR/QMS). The structure and morphology of the materials were characterized by scanning electron microscope (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Additionally, the mechanical properties were tested by tensile tests. An in-depth analysis revealed that the HDPE-pectin-ZnO interactions are crucial for the structural and performance properties of the final composite. The used biopolymer reacts with ZnO via ionic interaction and through hydrogen bond in the case of HDPE.

Pectin based banana peel extract as a stabilizing agent in zinc oxide nanoparticles synthesis.

Various amounts of banana peel extract were successfully used as a stabilizing agent in the co-precipitation of zinc oxide nanoparticles. The obtained materials were characterized by means of Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDS), N2 physisorption, thermogravimetric analysis (TGA), and quadrupole mass spectroscopy (QMS). On account of using such a broad spectrum of analytic methods, a thorough description of the interactions between the organic ingredients of the extract and ZnO particles was presented. It was indicated that the banana peel extract is based on pectin. These carbohydrate macromolecules adsorb on ZnO surface due to presence of active carboxylic groups. By increasing the concentration of polysaccharides, pectin-pectin interactions were also observed. The amount of the extract used for the synthesis significantly influenced the crystalline structure of zinc oxide particles along with their size and morphology. The shape and size were varying from thin flakes (450 × 24 nm) when the smallest amount of the extract was used, through nanocones with pointed tips (210 × 120 nm) agglomerated in a flower-like structure, until cubic-shaped nanoparticles (20-40 nm) agglomerated in a pinecone-like structure (430 × 180 nm) when the biggest amount of the extract was applied. The obtained particles have displayed apromising antimicrobial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa) bacteria, and fungus (Candida albicans). The highest activity was demonstrated against S. aureus pathogen.