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The objective of this work deals with the realization of high O2-barrier blown films based on novel biodegradable blends of Polybutylene succinate (PBS) and Poly-vinyl alcohol (PVOH) for food packaging applications. Blends at different PBS/PVOH weight ratios (100/0, 80/20, 60/40, 0/100 wt%) were produced and their processability and miscibility was preliminary assessed by means of dynamic shear rheological tests. Afterwards, blown films were realized and then characterized in terms of chemical properties and oxygen barrier performance. The results revealed that, although immiscible, polymers in the blend show some degree of interaction. Moreover, as the concentration of PVOH in the films increased, a significant decrease in oxygen permeability was obtained with respect to the neat PBS film, up to 42% for the PBS/PVOH 60/40 sample. The findings of this study highlighted the promising perspectives of these films as sustainable packaging for sensitive foods with high O2-barrier requirements. [ABSTRACT FROM AUTHOR]

In this work, melt blending and co-extrusion techniques have been investigated as functionalization strategies to realize bilayer biodegradable films suitable for food packaging applications, combining enhanced barrier performance, good heat sealability and ductility. The ductile, heat sealable inner layer was realized by mixing Ecovio, a commercial blend based on polylactide (PLA) and polybutylene adipate terephthalate (PBAT) with an amorphous PLA grade; the outer barrier layer, on its side, was realized by blending poly(hydroxybutyrate) (PHB) with a semicrystalline PLA grade. Three different structures were realized changing the relative thicknesses of the two layers, and were characterized for their surface wettability, O2 barrier, heat-sealability and tensile properties. The results highlighted the impact of the bilayer films layout on the functional performance, and pointed out the attractiveness of the developed structures for food packaging applications where barrier to oxygen is critical to reduce oxidative processes. [ABSTRACT FROM AUTHOR]

In order to verify the possibility of manufacturing good quality articles by recycled polypropylene (PP), a study on the effect of many recycling operations on the rheological and mechanical properties of PP was conducted. The amount of degradation occurring during the reprocessing was estimated in the melt state by means of rheological measurements and the results obtained were correlated with the weight average molecular weight [M.sub.w] and the molecular weight distribution MWD. Since the properties in the solid state are strictly dependent upon the molecular structure parameters and the morphology, mechanical properties were checked on films produced from virgin and recycled PP with a cast technology. Moreover, in order to estimate the effect of film composition and of the number of reprocessings on the final properties of the manufactured articles, blend films having different percentages of PP recycled several times and virgin PP were prepared., INTRODUCTION In the plastics industry, reprocessing waste material arising from normal processing operations is a common practice. This procedure, known as primary recycling, is done because it allows processors to [...]

In the present work, the suitability of Polylactic acid (PLA) / Poly-ß-hydroxybutyrate (PHB) blends for blown film extrusion was evaluated in a broad range of compositions, obtaining films with improved performance for food packaging applications. Blending PHB with PLA enhanced the processability of the systems for the film blowing process than neat PLA. Moreover, even though the polymers were found to be immiscible, the addition of PHB improved the crystallization of PLA, with a consequent increase in the stiffness, barrier properties and light-screening ability of the final developed systems. An increase in the ductility of the films was also achieved with a PHB content up to 30 wt.%. Correlations between the transparency and the crystallinity degree, and between the oxygen permeability and the elastic modulus of the films were also evaluated. [ABSTRACT FROM AUTHOR]

Post-consumer flexible packaging abandoned in seas and rivers represent an important environmental problem: their recovery is still a challenge and the management of the recovered material is equally difficult since, due to their heterogenicity and to their long-time permanence in seas or rivers, these plastics present various issues related to high incompatibility, hygroscopicity and presence of bad smells. All this translates into poor processability and mechanical performance and low organoleptic quality. The aim of this work is to characterize the seas and rivers plastic waste (SRPW) composition and to perform a preliminary investigation on the effectiveness of two different mineral fillers as reinforcing and compatibilizing agents for SRPW, in view of possible second-life applications of this waste. In particular, an organo-modified montmorillonite (Dellite 67G) and a natural sodium zeolite mineral (Zeolite 4A), loaded at 5 wt%, were considered for improving the processability and properties of SRPW blown films. The combined use of a polymeric compatibilizer (polyolefin block copolymer grafted with 0.4 wt% maleic anhydride was also considered, in order both to improve the filler dispersion within the polymer and to compatibilize the main constituents of SRPW. The results demonstrated that the addition of both fillers to SRPW leaves essentially unchanged the thermal stability, but gives interesting improvements mainly in terms of stiffness. The effects are more significant when the nanometric Dellite 67G is added, than for the micrometric Zeolite 4A, especially in compatibilized systems. [ABSTRACT FROM AUTHOR]

This study concerned with the upgrading of a mixed polyolefin material, obtained by the sorting and mechanical recycling of flexible packaging of small size (< 0.125 m2). It is mainly composed of polyethylene and a minor amount of polypropylene, with traces of polar contaminants. These latter are responsible for material's hygroscopicity, which negatively affects its processability and final performances. In the present work, the recyclate was melt compounded with different amounts of a nanometric natural zeolite by means of a single-screw extruder. The idea was to take advantage of the potential double function of this additive, as desiccant and reinforcement. The neat recyclate and its blends with the nanozeolite were extruded in the form of ribbons that were submitted to tensile mechanical tests. Significant increases of both stiffness and strain at break were observed for the systems Fil-s/nanozeolite compared to the neat recyclate, due to an efficient drying and reinforcement action of the selected nanozeolite, despite the non-optimal dispersion of the nanofiller. [ABSTRACT FROM AUTHOR]