Surface and Microstructural Failures of PET-Coated ECCS Plates by Salmon-Polymer Interaction
The new types of knowledge-intensive, multilayer containers consist of steel plates protected against corrosion by nanometric electrolytic chromium (Cr0) and chromium oxide (Cr2O3) layers chemically bonded to polyethylene terephthalate (PET) polymer coating to preserve food. It was observed that after emptying the cans, the salmon adhered to the polymer coating, changing its color, and that this adhesion increased with longer storage times. This work was aimed at determining the product-container interactions and their characterization by X-ray diffraction (XRD), confocal Raman and micro-Raman imaging and scanning electron microscopy (SEM) analysis. The zones of adhesion showed surface changes, variations in crystallinity and microstructural degradation of the PET coating. In addition, localized damages altering the functional properties of the multilayer system were observed as microcracking in the chromium layers that protect the steel. The degradation undergone was evaluated and characterized at a surface and microstructural level to establish the failure mechanisms, which were mainly associated with the activity of the adhered muscle and its biochemical components. Finally, a recommendation is done to preserve the useful life and functionality of cans for the preservation and efficient use of resources with an impact on recycling and environmental conservancy.
Comparison of the quality and storage stability of salmon packaged in various retort pouches
Abstract The effect of thin metal oxide coated barrier materials on the quality of shelf stable salmon was investigated. Four different retort pouch structures were used: Cast polypropylene (CPP); polyethylene terephthalate (PET)/silicon oxide-coated nylon/CPP (SIOX); Aluminum oxide-coated PET/nylon/CPP (ALOX); PET/aluminum foil/CPP (FOIL). To determine the amount of lipid oxidation in the salmon, thiobarbituric acid reactive substance (TBARS) was measured. Salmon packaged in SIOX pouches had higher TBARS value, 43.53 mili-extinction/g, than salmon packaged in FOIL pouches, 37.06 mili-extinction/g, after 8 weeks of storage. A multiple comparisons test was used to evaluate the sensory characteristics of the salmon. Salmon packaged in SIOX pouches had less acceptability, 4.11, than salmon packaged in FOIL pouches, 5.44, after week 8. Conversely, salmon packaged in ALOX pouches had similar sensory and TBARS value with salmon packaged in FOIL pouches. The barrier properties of each pouch material were also investigated. Oxygen permeability (OP, g μm/m 2 day kPa) of SIOX increased from 0.88 to 10.55 after retort processing. SIOX had an OP of 10.94 at week 8 while ALOX and FOIL had 0.51 and 0.47 of OP, respectively. Overall, shelf stable salmon packaged in ALOX had a shelf life comparable to salmon packaged in a traditional FOIL pouch material, while salmon packaged in SIOX had a significantly lower shelf life then either ALOX or FOIL.
Structural analysis of polymer-metal laminates by electron microscopy and infrared spectroscopy
SummariesPolymers and metals greatly differ in their deformation behaviour when they are conformed as laminate composites. Knowledge of the conformation of a polymer in the interface region is an important aspect in understanding the mechanism of adhesion in the composite.Characterisation and performance evaluations of the metal-polymer protective substrates, composed of a steel plate coated with electrolytic chromium (ECCS) and surface-protected by a poly(ethyleneterephthalate) (PET) co-rolled layer, were carried out by SEM (scanning electron microscopy) and TEM (transmission electron microscopy). The chemical composition and morphology of the components that allow for good adhesion of the metal-polymer plate were studied at the interface. ATR (attenuated total reflection), FT-IR (Fourier transform-infrared) and confocal Raman spectroscopy were employed to analyse the structural changes of the PET coatings on the ECCS plates resulting from the manufacturing processes and mechanical stresses.RésuméLes polymères et les métaux, quand ils constituent un stratifié composite, sont très différents les uns des autres, en ce qui concerne leur comportement à la déformation. La connaissance de la conformation d’un polymère dans la région de l’interface constitue un aspect important de l’interprétation du mécanisme d’adhésion dans le composite.La caractérisation et des évaluations de la performance des substrats métal-polymère protecteurs, composés d’une plaque d’acier revêtue du chrome électrolytique (ECCS) et dont la surface est protégée par une couche co-roulée du poly(éthylènetèréphthalate) (PET) ont été effectuées par SEM (microscopie électronique à balayage) et par TEM (microscopie électronique en transmission). La composition chimique et la morphologie des composants qui permettent la bonne adhésion de la plaque métal-polymère étaient étudiées au niveau de l’interface. ATR (réflexion totale attenuée), FT-IR (infrarouge par transformée de Fourier) et la spectroscopie Raman confocale ont été utilisées pour analyser les changements structuraux des revêtements PET sur les plaques ECCS, changements qui résultaient des procédés de fabrication et des stress mécaniques.ZusammenfassungPolymere und Metalle unterscheiden sich stark in ihrer Deformierbarkeit, selbst wenn sie als Laminatkomposit verarbeitet sind. Um die Adhäsionsmechanismen in einem Komposit zu verstehen, ist es wichtig, die Konformation des Polymeres an der Berührungsfläche zu verstehen. Wir verwendeten SEM (Scan-Elektron-Mikroskopie) und TEM (Transmissionselektronenmikroskopie) für die Charakterisierung und Leistungsbewertung von Metall/Polymerschutzsubstraten aus spezialverchromtem (ECCS), PET-beschichteten Feinstblech. Die chemische Komposition und Morphologie der Komponenten, die für die gute Adhäsion der Metall/Polymerplatte verantwortlich sind, wurden an der Berührungsfläche studiert. Abgeschwächte Total-Reflektion (ATR), FT-IR Spektroskopie (FT-IR) und konfokale Ramanspektroskopie wurden eingesetzt, um die Strukturveränderungen der PET-Schicht und des verchromten Bleches durch den Herstellungsprozeß und mechanischen Stress zu ermitteln.