Conversion of Recycled Polymers/Fibers Into Melt-Blown Nonwovens

Being a simple one-step process for converting polymer directly into a nonwoven fabric, melt blowing is ideally suited for processing of several recycled plastics. The process uses hot air to draw the fibers and does not require precise, individual control of each filament as in the conventional fiber-spinning processes. Recycled polypropylenes (PPs) from several sources were investigated as candidates for melt blowing. Waste from spun-bond line and spun-bond-melt-blown-spun-bond (SMS) fabrics were pelletized and then melt blown at our facility. The feasibility of using a melt-blowing line with an extruder gear pump unit to remelt the waste fibers/web and feed it with the molten virgin polymer stream coming from the main extruder was explored. A 1000 MFR virgin PP resin and fabrics produced from that polymer were used for this investigation. Fabrics were characterized in all the cases for their performance properties. Some of the relevant data are reported here. It was observed that in most of the cases, fabrics with good properties could be produced at high throughputs, thus demonstrating that most of the plant waste can be reused.     

ZnO、ZnO/ZnS和ZnO/ZnS/α-Fe_2O_3纳米复合材料的光致发光行为及可见光催化活性（英文）

为了获得用于染料甲基橙(MEO)降解的高效、经济、易得的光催化剂,采用简单的化学合成法在水溶液介质中制备ZnO、ZnO/ZnS和ZnO/ZnS/α-Fe_2O_3纳米复合材料。利用X射线衍射(XRD)和BET技术测定合成材料的物相、结晶度、表面结构和表面行为。X射线衍射结果表明,ZnO、ZnO/ZnS和ZnO/ZnS/α-Fe2O3纳米材料结晶良好。根据XRD谱中各峰的强度,确定纳米复合材料的组成。BET分析表明,所制备的材料具有介孔行为、Ⅳ型(吸附脱附)曲线和H4型迟滞现象。3种材料中,ZnO/ZnS/α-Fe_2O_3复合材料的比表面积最大。利用紫外-可见光谱分析,测定材料的带隙能,光致发光光谱(PL)则用来确定材料的发射行为和表面缺陷。在PL光谱中,ZnO/ZnS的紫外峰强度比ZnO的低,且ZnO/ZnS/α-Fe_2O_3的紫外峰强度更低。与ZnO相比,ZnO/ZnS的可见发射光谱强度增大,且ZnO/ZnS/α-Fe_2O_3的可见发射光谱强度比ZnO/ZnS的更大。所合成的材料被用作染料甲基橙降解的光催化剂。光降解数据表明,3种染料甲基橙降解的光催化剂中ZnO/ZnS/α-Fe_2O_3是最佳的。紫外光发射峰强度的降低和可见光发射强度的增大导致电子和空穴复合减少,因而使得ZnO/ZnS/α-Fe_2O_3具有最高的光催化活性。     

Single step green process for the preparation of antimicrobial nanotextiles by wet chemical and sonochemical methods

Abstract

In this work, the green synthesis of silver nanoparticles (AgNPs) was carried out by using Zanthoxylum rhesta plant’s fruit extract for the first time. The green synthesis and in situ deposition of AgNPs on cellulose fibers in cotton was carried out by wet and sonochemical methods. The AgNPs and AgNPs-deposited cotton fabrics were fully characterized. The crystallite size of particles obtained by both methods was around 37?nm and the hydrodynamic diameters were in the range of 69 to 184?nm and 75 to 111?nm. The scanning electron microscopy (SEM) images showed uniform deposition of the nanoparticles on cotton fabrics. The AgNPs-deposited cotton fabrics showed excellent antibacterial activities against gram positive and gram negative bacteria namely, Escherichia coli (E-coli), Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis. This work presents a significant advancement in the preparation of antimicrobial nanotextiles by a smart combination of green synthesis and in situ deposition approach.     

Binder fiber distribution and tensile properties of thermally point bonded cotton‐based nonwovens

Cotton‐based nonwovens are generally produced by carding and then bonding. One of the most important characteristics of nonwoven materials is the uniformity of their structure and properties. However, the carded webs always have irregularities caused by processing and material variables. The binder fiber distribution in carded cotton‐based nonwoven fabrics was analyzed based on the crystallization behavior of one of the components of the binder fibers by DSC. The effects of process parameters, such as bonding temperature and binder fiber component, on the uniformity were discussed in detail in this article. Also, the relationship of binder fiber distribution and the strip tensile property and single‐bond tensile strength were investigated. The results showed that if the binder fibers were not well distributed in the fabric, it would be hard to get the same trend of temperature effect on tensile property for the strip and single‐bond tests. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3148–3155, 2004     

Microstructural Characterization and Role of Glassy Layer Developed on Inconel 690 During a Nuclear High-Level Waste Vitrification Process

The interaction of Inconel 690 metallic components with borosilicate melt leads to development of a partially amorphous and a partially crystalline layer within borosilicate melt adjacent to the interface. Such a heterogeneous layer is referred to here as a glassy layer. In the present investigation, the glassy layer is constituted of several phases, e.g. a Cr₂O₃ layer, a Ni₂CrO₄ needle, and NiCr₂O₄ cubic phases. Incorporation of such a glassy layer within the melt pool can lead to significant microstructural changes in the melt. Formation of barium chromate and nickel silicate has been observed in a sodium barium borosilicate melt with excess amount of Cr₂O₃ and NiO, respectively.     

Studies on Dynamic Adsorption Behaviour of Ethyl Acetate from Air on 5A and 13X Molecular Sieves

Experimental data for dynamic adsorption of ethyl acetate present in air using 5A and 13X molecular sieves are generated with variations of inlet adsorbate concentration, inlet velocity and bed diameter to bed length ratio to study their effects on the adsorber bed performance. Mathematical model based on Linear Driving Force approximation is validated with experimental data and simulated to understand effects of other pertinent parameters such as overall mass transfer coefficient, saturation capacity and bed to wall heat transfer coefficient. 13X molecular sieve with higher capacity than 5A shows closer to ideal adsorption behaviour. Mass transfer rate is controlled by pore diffusion.     

Assessing Impacts of Conservation Measures on Watershed Hydrology Using MIKE SHE Model in the Face of Climate Change

Climate change triggers changes in temperature, precipitation, evapotranspiration, etc. and has a significant impact on water resources in many regions. Considering the increasing scarcity of water as a result of climate change, conservation of water and groundwater recharge have become crucial factors for water resources planning and management. In this paper, an attempt is made to study the detailed hydrological behaviour of a treated watershed using physically based distributed hydrological modelling system MIKE SHE to assess the impact of conservation measures on watershed hydrology considering future climate change. Three hypothetical management scenarios are simulated for the period 2010–2040. RegCM4 regional climate model is used in the study for RCP 4.5 and RCP 8.5 scenarios. Detailed hydrological water balance is extracted for individual years from 1979 to 2009 to compare relevant components. The evaluation for base period shows 10.06% reduction in surface runoff and 11.33% enhancement in groundwater recharge. Further simulation with RCP 4.5 and RCP 8.5 scenarios show notable reduction in surface runoff and increase in groundwater recharge. The structures in the micro-watershed influence the surface runoff and increase infiltration into the soil, resulting in higher groundwater recharge. MIKE SHE simulations for various structures management scenarios establish the role of conservation measures in reducing surface runoff and enhancing groundwater recharge under substantial effect of climate change. The results will assist in decision-making on watershed development plans in quantitative terms, including planning for water conservation measures in the face of climate change.

     

Compact model and circuit simulations for asymmetric, independent gate FinFETs

We present a rigorous surface-potential-based compact model of independent-gate asymmetric FinFETs enabled by solving several long-standing theoretical problems. The model is verified with TCAD simulations and is implemented in a standard circuit simulator. Simulation examples for both digital and analog circuits verify good model convergence and demonstrate the capabilities of new circuit topologies that can be implemented using independent-gate asymmetric FinFETs.     

Fe-EBT Chelate Complex: A Novel Mean for Growth of α-FeOOH and γ-Fe2O3 Nanostructures

Acicular goethite (α-FeOOH) and worm-like maghamite (γ-Fe₂O₃) nanostructures have been prepared adopting a novel route, using Na₂[Fe(HL)₂(H₂O)₂] chelate complex in alkaline medium. It is found that concentration of hydrated Fe(III) ions increased with increasing temperature, which later play a key role in generation of different phases of iron oxide. Phase and morphology of the products are investigated using XRD, FTIR, SEM, and TEM analysis. Using UV-Vis spectra, various electronic transitions of goethite and maghamite particles are examined. Maghamite nanostructures exhibit superparamagnetic property at room temperature. On the basis of experimental observations and analytical data, growth mechanism of the nanostructures is discussed.     

Protective activities of some phenolic 1,3-diketones against lipid peroxidation: possible involvement of the 1,3-diketone moiety

The protective activities of four ginger-derived phenolic 1,3-diketones (1-4) and curcumin (5) against lipid peroxidation was studied by using different biologically relevant model systems and pulse radiolysis. The extraordinary activity of 5 vis-à-vis 1-4 against Fe(2+)-mediated peroxidation may be attributed to the additional phenolic hydroxy group in the former, which lends it better iron-chelating and radical-scavenging properties. In iron-independent peroxidation, however, the ginger constituent [6]-dehydrogingerdione (1) showed activity comparable to that of 5; this indicates its higher affinity for the lipid peroxide radical (LOO(.)), due to its higher hydrophobicity. A very high rate constant for the reaction between 1 and Cl(3)COO(.), measured by pulse radiolysis, not only confirmed this, but also established the superior antioxidant efficacy of 1 in comparison to vitamins E and C. This was also evident from the results obtained from a liposomal peroxidation study with 1 and vitamin C. This study also established a synergistic effect of the latter on the antioxidant activity of 1. HPLC analysis of the products of the reaction between 1 and Cl(3)COO(.) revealed the formation of higher concentrations of ferulic acid (7), along with vanillin (6). The presence of ascorbate affected the generation of 7 more than it did that of 6. On this basis, a mechanism for the antioxidant action of 1 has been proposed, which suggests the contribution of the phenolic group as well as the active methylene group of the 1,3-diketones.