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Showing 3 results for Mahmudi


Volume 9, Issue 1 (Winter 2018)
Abstract

Aims: Nylon or polyamide is one of the most used and most important polymers used in the plastic and fiber industries of the world. For this reason, its use is less sensitive to the properties of its very poor biodegradability. Therefore, the aim of the present study was the biodegradability modification of synthetic polyamide 6 (pa6) fibers via in-situ melt blending with recycled poly (lactic) acid plastic food container flakes (r-PLA) during the melt spinning process.
Materials & Methods: In this experimental study, polyamide chips 6 in textile industry and Poly (Lactic) Acid Plastic Disposable Container Flakes were used. The weight loss, mechanical properties, and surface morphology variations of pure and modified fiber samples after soil burial test were analyzed for comprehensive biodegradability study of the modified fiber samples. Data were analyzed by One-Way Analysis of Variance.
Findings: The mechanical tests performed on Norris fiber showed successful production of blend fibers with the percentages of 5, 10, 20, 30, and 40 of the components of r-PLA and A 50% r-PLA fiber sample did not have acceptable mechanical properties. The changes of PA6/r-PLA blended fibers with a significant increase in r-PLA component in the PA6 substrate were significant.
Conclusion: The blend modified of PA6 and Poly (Lactic) recycled samples, with a composition containing from 5% to 40% of the dispersed recycled poly-lactic acid fraction have successfully melt spinning capability. By increasing the percentage of recycled poly lactic acid in the blended fibers, the mechanical properties show improvement in samples of 5% and 10% by weight and show reduction in higher percentages. Iincreasing the biodegradability of modified PA 6 fibers with increasing the r-PLA content is obviously confirmed.

Volume 13, Issue 55 (9-2015)
Abstract

Chemical preservatives are usually used to reduce or eliminate pathogenic or spoilage microorganisms but their inordinate applications have resulted in toxigenic residuals and adverse effects on consumers, So many researches have been done to substitute the chemicals with naturally occurring compounds, especially plant essential oils. In this study, the chemical compositions of essential Thymus kotschyanus were identified with set GC-MS. Then organoleptic properties, microbial and physicochemical quality of Doogh sample prepared with adding different concentration Thymus kotschyanus essential oil were investigated during 14 day storage. Results of GC-MS analysis indicated that thymol (51.1 %), p-cymene (13.78 %) and γ-terpinene (9.03 %) comprised the highest amount of this EO. T. kotschyanus EO destroyed E.coli O157:H7 in addetive low concentrations to Doogh in same the early days and the MIC that  determined by the micro dilution method was 470µg/ml. Based on the results, essential oil doesn’t have significant changes in Doogh physico-chemical properties excepion total solid that essentail Doogh free comparsion with Doogh contain 100 and 200 ppm make significant changes(p<0.05), the Doogh that contain 50 ppm was accepted by panelist. The addition of this EO has no adverse effect on the physicochemical and organoleptic properties of Doogh, also this EO effective substances could be purified and used as natural antibacterial agent, solely or along with others techniques, to prolong food shelf life.

Volume 16, Issue 11 (1-2017)
Abstract

In the present study, AM60 magnesium alloy was casting and then subjected to hot extrusion process. Next, Multi Directional Forging (MDF) experiments with six pass numbers were conducted to investigate the influence of the operation on the microstructure and mechanical properties of these alloys. The shear punch test (SPT) and Vickers microhardness test were employed to evaluate the mechanical properties of the extruded and MDFed samples. Both the shear yield stress (SYS) and ultimate shear strength (USS) obtained from the shear punch test increased just after two passes but decreased with further pressing, although it was expected that the grains became finer with increasing the pass number. After two passes USS increased from 121.58 MPa to 142.42 MPa. This rise and fall indicates that texture softening overcame the strengthening effects of the grain refinement. The Vickers microhardness was measured across the cross sections of the extruded and MDFed samples, the results of this test also confirms that rise and fall procedure. The average microhardness of the extruded and MDFed samples were found to be respectively 73.50, 85.93, 82.26 and 77.83 HV for the extruded and 2,4 and 6 passes of MDFed, which confirms SPT results. Optical micrographs showed that processing by MDF reduces the grain size from 11.22 to 1.91 µm after 6 passes.

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