The role of prepared ZnO nanoparticles on improvement of mechanical and antibacterial properties of flexible polyurethane foams: experimental modeling

2017 ◽  
Vol 75 (4) ◽  
pp. 1519-1533 ◽  
Author(s):  
M. S. Seyed Dorraji ◽  
M. H. Rasoulifard ◽  
M. Shajeri ◽  
H. R. Ashjari ◽  
M. Azizi ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Antibacterial Properties ◽  
Polyurethane Foams ◽  
Experimental Modeling ◽  
Flexible Polyurethane

scholarly journals Some key Factors Influencing the Flame Retardancy of EDA-DOPO Containing Flexible Polyurethane Foams

2018 ◽  
Author(s):  
Agnieszka Przystaś ◽  
Milijana Jovic ◽  
Khalifah A Salmeia ◽  
Daniel Rentsch ◽  
Laurent Ferry ◽  
...  
Keyword(s):  
Flame Retardancy ◽  
High Speed ◽  
Combustion Efficiency ◽  
Polyurethane Foams ◽  
Key Factors ◽  
Ul 94 ◽  
Combustion Flow ◽  
Flexible Polyurethane ◽  
Pu Foams

In this work we have investigated the role of various additives (emulsifier, anti-dripping agent) and formulation procedure (pre- dispersion of solid additives in polyol via milling) which influence the flame retardancy of 6,6′-[ethan-1,2-diylbis(azandiyl)]bis(6H-dibenzo[c,e][1,2]oxaphosphin-6-oxid) (EDA-DOPO) containing flexible polyurethane foams. For comparison, the flame retardancy of two additional structurally analogues bridged 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based compounds i.e. ethanolamine-DOPO (ETA-DOPO) and ethylene glycol-DOPO (EG-DOPO) were also evaluated together with EDA-DOPO in flexible PU foams of various formulations. The flame retardancy of three bridged-DOPO compounds depends on the type of PU formulation. For certain PU formulation containing EDA-DOPO, lower fire performance was observed. Addition of emulsifier and polytetrafluoroethylene (PTFE) to these PU formulations influenced positively the flame retardancy of EDA-DOPO/PU foams. In addition, dispersion of EDA-DOPO and PTFE via milling in polyol improved the flame retardancy of the PU foams. Mechanistic studies performed using pyrolysis combustion flow calorimetry (PCFC) and its coupling to FTIR showed no difference in the combustion efficiency of the bridged-DOPO compounds in PU foams. From these PCFC experiments we can conclude that these bridged-DOPO compounds and their decomposition products may work primarily in the gas phase as flame inhibitors. Physiochemical behavior of additives in PU formulation responsible for the improvement in the flame retardancy of PU foams was further investigated by studying the dripping behavior of the PU foams in UL 94 HB test. A high-speed camera was used to study the dripping behavior in the UL 94 HB test and results indicate a considerable reduction of a total number of melt drips and flaming drips for the flame retardant formulations. This reduction in melt drips and flaming drips during the UL 94 HB tests help PU foams achieve higher fire classification.

Electrochemical behaviour of chromium–graphene composite coating

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62083-62090 ◽  
Author(s):  
Rekha M. Y. ◽  
M. K. Punith Kumar ◽  
Chandan Srivastava
Keyword(s):  
Composite Coating ◽  
Zno Nanoparticles ◽  
Electrochemical Behaviour ◽  
Chromium Coating ◽  
Corrosion Resistant ◽  
Graphene Composite ◽  
Pure Chromium

This work illustrates the role of graphene in enhancing the corrosion resistant properties of chromium–graphene composite coating when compared to the corrosion resistant properties of pure chromium coating containing ZnO nanoparticles.

Preparation of polycrystalline ZnO nanoparticles loaded onto graphene oxide and their antibacterial properties

2021 ◽  
pp. 102531
Author(s):  
Xin Zhang ◽  
Huanxian Shi ◽  
Enzhou Liu ◽  
Xiaoyun Hu ◽  
Ke Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Zno Nanoparticles ◽  
Antibacterial Properties

scholarly journals Effects of Rifaximin on Luminal and Wall-Adhered Gut Commensal Microbiota in Mice

2021 ◽  
Vol 22 (2) ◽  
pp. 500
Author(s):  
Marina Ferrer ◽  
Mònica Aguilera ◽  
Vicente Martinez
Keyword(s):  
Fluorescent In Situ Hybridization ◽  
Fragment Length Polymorphism ◽  
Functional Gastrointestinal Disorders ◽  
Antibacterial Properties ◽  
Broad Spectrum Antibiotic ◽  
Commensal Microbiota ◽  
Bacterial Biodiversity ◽  
Rule Out

Rifaximin is a broad-spectrum antibiotic that ameliorates symptomatology in inflammatory/functional gastrointestinal disorders. We assessed changes in gut commensal microbiota (GCM) and Toll-like receptors (TLRs) associated to rifaximin treatment in mice. Adult C57BL/6NCrl mice were treated (7/14 days) with rifaximin (50/150 mg/mouse/day, PO). Luminal and wall-adhered ceco-colonic GCM were characterized by fluorescent in situ hybridization (FISH) and microbial profiles determined by terminal restriction fragment length polymorphism (T-RFLP). Colonic expression of TLR2/3/4/5/7 and immune-related markers was assessed (RT-qPCR). Regardless the period of treatment or the dose, rifaximin did not alter total bacterial counts or bacterial biodiversity. Only a modest increase in Bacteroides spp. (150 mg/1-week treatment) was detected. In control conditions, only Clostridium spp. and Bifidobacterium spp. were found attached to the colonic epithelium. Rifaximin showed a tendency to favour their adherence after a 1-week, but not 2-week, treatment period. Minor up-regulation in TLRs expression was observed. Only the 50 mg dose for 1-week led to a significant increase (by 3-fold) in TLR-4 expression. No changes in the expression of immune-related markers were observed. Rifaximin, although its antibacterial properties, induces minor changes in luminal and wall-adhered GCM in healthy mice. Moreover, no modulation of TLRs or local immune systems was observed. These findings, in normal conditions, do not rule out a modulatory role of rifaximin in inflammatory and or dysbiotic states of the gut.

In situ monitoring of isophorone diisocyanate-based flexible polyurethane foams formation

2016 ◽  
Vol 54 (1) ◽  
pp. 37-52 ◽  
Author(s):  
I Eceiza ◽  
L Irusta ◽  
A Barrio ◽  
MJ Fernández-Berridi
Keyword(s):  
Foam Height ◽  
Polyurethane Foams ◽  
In Situ Monitoring ◽  
Generation Process ◽  
Isophorone Diisocyanate ◽  
Experimental Conditions ◽  
Foaming Process ◽  
Foam Generation ◽  
Flexible Polyurethane

Novel isophorone diisocyanate-based flexible polyurethane foams were prepared by the one-step method in a computerized foam qualification system (FOAMAT). The experimental conditions to obtain this type of foams, in relation to the nature and concentration of catalysts as well as the reaction temperature, were established as no data were available in scientific literature. The chemical reactions occurring during the foam generation process were monitored in situ by attenuated total reflectance-FTIR spectroscopy. The kinetics of the foam generation was fitted to an nth order model and the data showed that the foaming process adjusted to a first-order kinetics. The physical changes as pressure, foam height, and dielectric polarization were monitored by the FOAM software (FOAMAT). According to these parameters, the foaming process was divided into four steps: bubble growth, bubble packing, cell opening, and final curing.

scholarly journals Mutagenicity of ZnO nanoparticles in mammalian cells: Role of physicochemical transformations under the aging process

2015 ◽  
Vol 9 (8) ◽  
pp. 972-982 ◽  
Author(s):  
Mei M. Wang ◽  
Yi C. Wang ◽  
Xi N. Wang ◽  
Yun Liu ◽  
Hong Zhang ◽  
...  
Keyword(s):  
Zno Nanoparticles ◽  
Mammalian Cells ◽  
Aging Process
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