Single-Step Application of Polyelectrolyte Complex Films as Oxygen Barrier Coatings

Abstract Zirconia-based thermal barrier coatings (TBCs), produced using Vacuum Plasma Spray (VPS) technology, were recently subjected to burner rig testing. The VPS TBC performance was compared to TBCs deposited using conventional Atmospheric Plasma Sprayed (APS) and Electron Beam Physical Vapor Deposition (EB-PVD) techniques. All of the coatings consisted of an MCrAlY bond coat and a partially stabilized ZrO2-8%Y2O3 (PSZ) top coat. The TBC coated pins (6.35 mm in diameter) were tested using gas temperatures ranging from 110CC to 1500°C. The pins were tested to failure under severe conditions (1500°C gas temperature, with no internal cooling). The initial testing indicated that under typical operating gas temperatures (1400°C), the VPS TBC performance was comparable, if not superior, to conventional TBCs. Following the encouraging results, thick composite TBCs, produced in a single-step operation, were investigated. Preliminary work on ZrO2-8% Y2O3/Ca2SiO4 composite TBCs with interlayer grading included thermal shock testing and temperature drop measurements across the TBC. The composite TBC thicknesses ranged from 850µm to 1.8 mm. Initial results indicate that thick adherent composite TBCs, with high resistance to severe thermal shock, can be produced in a single step using the VPS process.

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Nano-inspired oxygen barrier coatings for food packaging applications: An overview

Trends in Food Science & Technology ◽

10.1016/j.tifs.2020.01.024 ◽

2020 ◽

Vol 97 ◽

pp. 210-220 ◽

Cited By ~ 5

Author(s):

Cesare Rovera ◽

Masoud Ghaani ◽

Stefano Farris

Keyword(s):

Food Packaging ◽

Oxygen Barrier ◽

Barrier Coatings ◽

Inspired Oxygen

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Enzymatic Hydrolysis of Bacterial Cellulose for the Production of Nanocrystals for the Food Packaging Industry

Nanomaterials ◽

10.3390/nano10040735 ◽

2020 ◽

Vol 10 (4) ◽

pp. 735

Author(s):

Cesare Rovera ◽

Filippo Fiori ◽

Silvia Trabattoni ◽

Diego Romano ◽

Stefano Farris

Keyword(s):

Enzymatic Hydrolysis ◽

Bacterial Cellulose ◽

Food Packaging ◽

Hydrolytic Activity ◽

High Oxygen ◽

Oxygen Barrier ◽

Final State ◽

Barrier Coatings ◽

Significant Difference ◽

Packaging Industry

Bacterial cellulose nanocrystals (BCNCs) obtained by enzymatic hydrolysis have been loaded in pullulan biopolymer for use as nanoparticles in the generation of high-oxygen barrier coatings intended for food packaging applications. Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was hydrolyzed by two different enzymatic treatments, i.e., using endo-1,4-β-glucanases (EGs) from Thermobifida halotolerans and cellulase from Trichoderma reesei. The hydrolytic activity was compared by means of turbidity experiments over a period of 145 h, whereas BCNCs in their final state were compared, in terms of size and morphology, by atomic force microscopy (AFM) and dynamic light scattering (DLS). Though both treatments led to particles of similar size, a greater amount of nano-sized particles (≈250 nm) were observed in the system that also included cellulase enzymes. Unexpectedly, transmission electron microscopy (TEM) revealed that cellulose nanoparticles were round-shaped and made of 4–5 short (150–180 nm) piled whiskers. Pullulan/BCNCs nanocomposite coatings allowed an increase in the overall oxygen barrier performance, of more than two and one orders of magnitude (≈0.7 mL·m−2·24 h−1), of pure polyethylene terephthalate (PET) (≈120 mL·m−2·24 h−1) as well as pullulan/coated PET (≈6 mL·m−2·24 h−1), with no significant difference between treatments (hydrolysis mediated by EGs or with the addition of cellulase). BCNCs obtained by enzymatic hydrolysis have the potential to generate high oxygen barrier coatings for the food packaging industry.

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