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.
Ultrathin Wafer Pre-Assembly and Assembly Process Technologies: A Review
Ultrathin silicon wafer technology is reviewed in terms of the semiconductor applications, critical challenges, and wafer pre-assembly and assembly process technologies and their underlying mechanisms. Mechanical backgrinding has been the standard process for wafer thinning in the semiconductor industry owing to its low cost and productivity. As the thickness requirement of wafers is reduced to below 100 μm, many challenges are being faced due to wafer/die bow, mechanical strength, wafer handling, total thickness variation (TTV), dicing, and packaging assembly. Various ultrathin wafer processing and assembly technologies have been developed to address these challenges. These include wafer carrier systems to handle ultrathin wafers; backgrinding subsurface damage and surface roughness reduction, and post-grinding treatment to increase wafer/die strength; improved wafer carrier flatness and backgrinding auto-TTV control to improve TTV; wafer dicing technologies to reduce die sidewall damage to increase die strength; and assembly methods for die pick-up, die transfer, die attachment, and wire bonding. Where applicable, current process issues and limitations, and future work needed are highlighted.