International Journal of Material Science
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Open Access journal
ISSN (Print) 2226-4531 - ISSN (Online) 2226-4523
Published by Science and Engineering Publishing Company [49 journals]
- Nisin as an Antibacterial Substance in Active Packaging: 2. Use of
Ethylene Methyl Acrylate and Co-Polyamide to Enhance Its Effectiveness
Abstract: Nisin as an Antibacterial Substance in Active Packaging: 2. Use of Ethylene Methyl Acrylate and Co-Polyamide to Enhance Its Effectiveness
Author Gilad ReichenbergAmos OphirYiftach Ni
This work deals with flexible thermoplastic films incorporating nisin for antibacterial active packaging purposes. A novel approach was used to gain control over nisin release profile from a thermoplastic film with the aim of enhancing nisin antibacterial efficiency. The release profile of nisin from active packaging to foodstuff is a key factor concerning the enhancement of its efficiency. In our last study, polymer blends of EVA and co-polyamide were used to control nisin migration from film to foodstuff simulant. In this part, EVA was replaced by EMA due to applicable reasons. Samples of 400μm thick were produced by using a laboratory twin screw compounder and a laboratory hot press (same as part 1). Release kinetics and antibacterial tests were done in order to characterize different target bacteria response to different migration profiles. Listeria ATCC 33090 was used as target bacteria. Nisin migration profile to foodstuff simulant was determined by Lowry’s protocol. Osmotic pressure driven release mechanism appears to be the migration mechanism and diffusion kinetics was dominant. Results show that polymer blend continues phase determines the diffusion coefficient. Furthermore, films were characterized for their elastic modulus properties as supplementary data. Elastic modulus and nisin concentration in foodstuff stimulant show an inverse proportion. It is concluded that this proportion is related to the formation of more surface area that is exposed for migration.
- Experimental Investigations on Thermal Analysis and Thermal
Characterization of Al 6061-Sic-Gr Hybrid Metal Matrix Composites
Abstract: Experimental Investigations on Thermal Analysis and Thermal Characterization of Al 6061-Sic-Gr Hybrid Metal Matrix Composites
Author S A MOHAN KRISHNAT N SHRIDHARL KRISHNA MURTH
Metal matrix composites are regarded to be one of the most predominant classifications in composite materials. The thermal characterization of hybrid metal matrix composites has been increasingly important in a wide range of applications. The coefficient of thermal expansion, thermal conductivity, thermal diffusivity and specific heat capacity are the most important properties of Metal Matrix Composites (MMCs). Since nearly all Metal Matrix Composites are used in various temperature ranges, measurement of thermal properties of MMCs as a function of temperature is necessary in order to know the behaviour of the material. In this research paper, the evaluation of thermal conductivity, thermal diffusivity, thermal expansivity and thermal capacity has been accomplished for Al 6061, Silicon Carbide and Graphite hybrid metal matrix composites from room temperature to 300°C. Aluminium based composites reinforced with Silicon Carbide and Graphite particles have been prepared by stir casting technique. The thermal behaviour of hybrid composites with different percentage compositions of reinforcements has been investigated. The results have indicated that the thermal properties of the different compositions of hybrid MMCs vary by the addition of Graphite with Silicon Carbide and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity and thermal conductivity of hybrid composites.
- Study And Characterization of A Metal Matrix Composite Reinfor Ced with
Abstract: Study And Characterization of A Metal Matrix Composite Reinfor Ced with Tantalum Carbide-TaC
Author Leiliane Alves OliveiraUílame Umbelino GomesCarlson Pereira SouzaSérgio Renato da Silva Soare
Steel is an alloy EUROFER promising for use in nuclear reactors, or in applications where the material is subjected to temperatures up to 550°C due to their lower creep resistance under. One way to increase this property, so that the steel work at higher temperatures it is necessary to prevent sliding of its grain boundaries. Factors that influence this slip contours are the morphology of the grains, the angle and speed of the grain boundaries. This speed can be decreased in the presence of a dispersed phase in the material, provided it is fine and homogeneously distributed. In this context, this paper presents the development of a new material metal matrix composite (MMC) which has as starting materials as stainless steel EUROFER 97, and two different kinds of tantalum carbide-TaC, one with average crystallite sizes 13.78 nm synthesized in UFRN and another with 40.66 nm supplied by Aldrich. In order to improve the mechanical properties of metal matrix was added by powder metallurgy, nano-sized particles of the two types of TaC. This paper discusses the effect of dispersion of carbides in the microstructure of sintered parts. Pure steel powders with the addition of 3% TaC UFRN and 3% TaC commercial respectively were ground for 5 hours in the planetary mill. Each of the resultant particulate samples were cold compacted under a uniaxial pressure of 600MPa in a cylindrical die 5 mm in diameter. Subsequently, the compressed were sintered in a vacuum oven at a temperature of 1250°C with an increment of 20°C and 10°C per minute and maintained at these isotherms for 60 minutes. The distribution, size and dispersion of steel and composite particles were determined by X-ray diffraction, laser particle size and scanning electron microscopy(SEM). The structures of the sintered bodies were observed by optical microscopy(OM) and scanning electron microscopy(SEM).