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1 – 10 of 484Kesavan Devarayan, Padmavathi P. and Kopperundevi Sivakami Nagaraju
Development of thin film sensors with pH function for noninvasive real-time monitoring of spoilage of packed seafood such as fish, crab and shrimp are described in this study. It…
Abstract
Purpose
Development of thin film sensors with pH function for noninvasive real-time monitoring of spoilage of packed seafood such as fish, crab and shrimp are described in this study. It is also the purpose of this study to enhance the leaching resistance of the sensors by using a suitable strategy and to quantitatively correlate the sensor’s halochromism with the total volatile amine.
Design/methodology/approach
To prepare halochromic sensors with better leaching resistance, biocompatible materials such as starch, agar, polyvinyl alcohol and cellulose acetate along with a halochromic dye were used to prepare the thin film sensors. These thin films were evaluated for monitoring the spoilage of packed seafood at room temperature, 4°C and −2°C up to 30 days. The halochromic sensors were characterized using UV-visible and FT-IR spectroscopy.
Findings
CIELab analyses of the halochromism of the thin film sensors revealed that the color changes exhibited by the sensors in response to the spoilage of seafood are visually distinguishable. Further, the halochromic response of the thin films was directly proportional to the amount of total volatile base nitrogen that evolved from the packed seafood. Excellent leaching resistance was observed for the developed thin film sensors. The halochromic property of the sensors is reversible and thus the sensors are recyclable. Besides, the thin film sensors exhibited significant biodegradability.
Originality/value
This study provides insights for use of different biocompatible polymers for obtaining enhanced leaching resistance in halochromic sensors. Further, the color changes exhibited by the sensors are in line with the total volatile amines evolved from the packed seafood. These results highlight the importance of the developed halochromic thin film sensors for real-time monitoring of the spoilage of packed seafood.
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POLYMERS are mixtures of compounds of similar chemical composition and of high molecular weights. Naturally occurring products such as rubber, cellulose, proteins and shellac…
Abstract
POLYMERS are mixtures of compounds of similar chemical composition and of high molecular weights. Naturally occurring products such as rubber, cellulose, proteins and shellac, extracted materials such as asphaltic bitumens, and synthetic products, produced by a polymerisation process, are all included under this heading.
Oleochemicals can be made from the components of renewable animal, marine and vegetable oils and fats. This oleochemical group of products is a large one, comprising fatty acids…
Abstract
Oleochemicals can be made from the components of renewable animal, marine and vegetable oils and fats. This oleochemical group of products is a large one, comprising fatty acids, glycerol and numerous derivatives of these including fatty alcohols, fatty esters, and nitrogen‐, phosphorus‐and sulphur‐containing materials. Polyoxyalkylated end products from the above, from heavy metal and water‐soluble soaps, epoxidised chemicals, polymer components, and the quarternary ammonium compounds are found. The oleochemicals of interest to the lubricants manufacturer are those which function in some specific manner. Anti‐corrosive, anti‐oxidant, anti‐squawk, anti‐stick, anti‐sludge, anti‐wear detergent, dispersant and oiliness agents, pour point depressants and viscosity modifying materials, are examples.
This article is intended to indicate some of the problems involved in obtaining latices which have practical utility. I shall be mainly concerned with copolymers of vinyl esters…
Abstract
This article is intended to indicate some of the problems involved in obtaining latices which have practical utility. I shall be mainly concerned with copolymers of vinyl esters and the various acrylic monomers and also with latices which are applied as such—not merely polymerised in emulsion as a convenient method of obtaining the solid polymer in particulate form.
Adhesion promoters: Some oleochemicals can promote the adhesion of polymers to various surfaces, e.g. stearic acid can increase the adhesion of polyolef ins to metals and to the…
Abstract
Adhesion promoters: Some oleochemicals can promote the adhesion of polymers to various surfaces, e.g. stearic acid can increase the adhesion of polyolef ins to metals and to the surfaces of other polymers. Erucamide is effective in the lamination of cellophane to polyethylene films, and alumina‐modified iron stearate has been found effective in aiding the adhesion of polyethylene to steel surfaces. The effect of oleamide on the adhesion of polyethylene to aluminium and to nylon 6 has been studied. Stearic acid had an adhesion promoting role in polyethylene/aluminium laminated packaging film. Barium stearate can effect the adhesiveness of poly(vinyl chloride).
Abstract
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Polymethacrylates are distinguished by transparency as well as by chemical and mechanical resistivity. This overview of the current status of the thermoplastic methacrylate solid…
Abstract
Polymethacrylates are distinguished by transparency as well as by chemical and mechanical resistivity. This overview of the current status of the thermoplastic methacrylate solid resins discusses synthesis, production processes, binder characteristics, and major areas of application.
Polyvinyl acetal resins have grown in use steadily over the past two decades. Pioneered by Monsanto under the trademarks Butvar® (polyvinyl butyral) and Formvar® (polyvinyl…
Abstract
Polyvinyl acetal resins have grown in use steadily over the past two decades. Pioneered by Monsanto under the trademarks Butvar® (polyvinyl butyral) and Formvar® (polyvinyl formal), the resins have a combination of properties making them ideal for applications in many different fields.
Evan Malone, Megan Berry and Hod Lipson
The paper's aim is to show the development of materials and methods which allow freeform fabrication of macroscopic Zn‐air electrochemical batteries. Freedom of geometric design…
Abstract
Purpose
The paper's aim is to show the development of materials and methods which allow freeform fabrication of macroscopic Zn‐air electrochemical batteries. Freedom of geometric design may allow for new possibilities in performance optimization.
Design/methodology/approach
The authors have formulated battery materials which are compatible with solid freeform fabrication (SFF) while retaining electrochemical functionality. Using SFF processes, they have fabricated six Zn‐air cylindrical batteries and quantitatively characterized them and comparable commercial batteries. They analyze their performance in light of models from the literature and they also present SFF of a flexible two‐cell battery of unusual geometry.
Findings
Under continuous discharge to 0.25 V/cell with a 100 Ω load, the cylindrical cells have a specific energy and power density in the range of 40‐70 J/g and 0.4‐1 mW/cm2, respectively, with a mass range of 8‐18 g. The commercial Zn‐air button cells tested produce 30‐750 J/g and 7‐9 mW/cm2 under the same conditions, and have a mass range of 0.2‐2 g. The two‐cell, flexible Zn‐air battery produces a nominal 2.8 V, open‐circuit.
Research limitations/implications
The freeform‐fabricated batteries have ∼10 percent of the normalized performance of the commercial batteries. High‐internal contact resistance, loss of electrolyte through evaporation, and inferior catalyst reagent quality are possible causes of inferior performance. Complicated material preparation and battery fabrication processes have limited the number of batteries fabricated and characterized, limiting the statistical significance of the results.
Practical implications
Performance enhancement will be necessary before the packaging efficiency and design freedom provided by freeform‐fabricated batteries will be of practical value.
Originality/value
The paper demonstrates a multi‐material SFF system, material formulations, and fabrication methods which together allow the fabrication of complete functional Zn‐air batteries. It provides the first quantitative characterization of completely freeform‐fabricated Zn‐air batteries and comparison to objective standards, and shows that highly unusual, functional battery designs incorporating flexibility, multiple cells, and unusual geometry may be freeform fabricated.
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he development of printed circuit technology is almost inseparable from the development of materials. Copper clad laminates could be said to have started with the discovery of…
Abstract
he development of printed circuit technology is almost inseparable from the development of materials. Copper clad laminates could be said to have started with the discovery of phenolic resins by Dr Leo Baekeland in 1909. He found that by using catalysts he could control the speed and extent of the reaction of phenol with formaldehyde, suspending the reaction at any time to add reinforcements. Using resins in a liquid form he was able to combine them with wood cloth, paper or fibre to build an insulating material.