scholarly journals PET Foams Surface Treated with Graphene Nanoplatelets: Evaluation of Thermal Resistance and Flame Retardancy

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 501
Author(s):  
Samuele Matta ◽  
Laura Giorgia Rizzi ◽  
Alberto Frache
Keyword(s):  
Fire Retardant ◽  
Graphene Nanoplatelets ◽  
Penetration Test ◽  
Cone Calorimetry ◽  
Sem Images ◽  
Morphological Effect ◽  
Liquid Solutions ◽  
Fire Retardant Properties ◽  
Combustion Tests ◽  
Scanning Electron

In this work, fire-retardant systems consisting of graphene nanoplatelets (GNPs) and dispersant agents were designed and applied on polyethylene terephthalate (PET) foam. Manual deposition from three different liquid solutions was performed in order to create a protective coating on the specimen’s surface. A very low amount of coating, between 1.5 and 3.5 wt%, was chosen for the preparation of coated samples. Flammability, flame penetration, and combustion tests demonstrated the improvement provided to the foam via coating. In particular, specimens with PSS/GNPs coating, compared to neat foam, were able to interrupt the flame during horizontal and vertical flammability tests and led to longer endurance times during the flame penetration test. Furthermore, during cone calorimetry tests, the time to ignition (TTI) increased and the peak of heat release rate (pHRR) was drastically reduced by up to 60% compared to that of the uncoated PET foam. Finally, ageing for 48 and 115 h at 160 °C was performed on coated specimens to evaluate the effect on flammability and combustion behavior. Scanning electron microscopy (SEM) images proved the morphological effect of the heat treatment on the surface, showing that the coating was uniformly distributed. In this case, fire-retardant properties were enhanced, even if fewer GNPs were used.

The fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers

2017 ◽  
Vol 88 (11) ◽  
pp. 1299-1307 ◽  
Author(s):  
Xiansheng Zhang ◽  
Xiaoning Tang ◽  
Ran Wang ◽  
Rui Wang ◽  
Xiong Yan ◽  
...  
Keyword(s):  
Heat Flux ◽  
Fire Retardant ◽  
Heat Fluxes ◽  
Gas Chromatography Mass Spectrometry ◽  
Cone Calorimetry ◽  
Small Molecular Weight ◽  
Absorption Bands ◽  
Pyrolysis Gas ◽  
Pyrolysis Mechanism ◽  
Fire Retardant Properties

In the present work, the fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers were investigated by cone calorimetry, scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and pyrolysis-gas chromatography-mass spectrometry. The fire retardant behaviors were reflected by the cone calorimeter data under heat fluxes of 35, 50, and 75 kW/m2. This demonstrated that, when exposed to higher heat flux, PSA fibers were ignited easier and burned more completely, indicated by lower time to ignition and higher peak heat release rate. It was further confirmed from the morphology of the residual chars that the original fiber shape can be kept at lower heat flux, but it changed into coherent carbonaceous chars with holes at higher heat flux. In comparison of the FTIR spectra of raw fibers with residual chars, it was noticed that upon heating, the amide linkage was more liable to be broken than that of sulfone groups. Additionally, with elevated heat flux, most of the absorption bands vanished and transformed into the typical feature of carbonaceous material. The pyrolysis products showed that some volatile products with small molecular weight, such as benzene, benzonitrile, and aniline, can be created at high temperature, which can be easily ignited. With this research, the fire retardant properties of PSA fibers are revealed and the corresponding pyrolysis mechanism is proposed, which can guide its application in practice.

The effect of nanocrystalline cellulose and TEMPO-oxidized nanocellulose on the compatibility of polypropylene/cyclic natural rubber blends

2020 ◽  
pp. 089270572095912
Author(s):  
IP Mahendra ◽  
B Wirjosentono ◽  
T Tamrin ◽  
H Ismail ◽  
JA Mendez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Natural Rubber ◽  
Nanocrystalline Cellulose ◽  
Mechanical And Thermal Properties ◽  
Interphase Surface ◽  
Sem Images ◽  
Morphological Effect ◽  
Rubber Blends ◽  
Compatibilizing Agent ◽  
Scanning Electron

The effect of nanocrystalline cellulose (NCC) and nanofiber cellulose (NFC) was estimated as a means of reinforcing and compatibilizing agent of polypropylene/ cyclic natural rubber (PP/CNR) blend in terms of mechanical and thermal properties. The morphological effect of NCC and NFC on the PP/CNR blend property was determined through several characterization techniques, i.e. SEM, contact and TGA/DTG. Scanning electron microscopy (SEM) images revealed that the addition of NCC and NFC became more homogenous than without the addition of nanocellulose. The improvement of nanocomposites was also observed on the result of interphase surface tension and thermal stability. This improvement was assumed as the result of physically/ chemically interaction of nanocellulose with the backbone of PP and CNR, in which the nanocellulose can be imagined acting as a bridge to link the PP and CNR’s backbone.

scholarly journals Layered Clay–Graphene Oxide Nanohybrids for the Reinforcement and Fire-Retardant Properties of Polyurea Matrix

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 66
Author(s):  
Mădălina Ioana Necolau ◽  
Celina Maria Damian ◽  
Radu Claudiu Fierăscu ◽  
Anita-Laura Chiriac ◽  
George Mihail Vlăsceanu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Great Influence ◽  
Fire Retardant ◽  
Mechanical Analysis ◽  
Cone Calorimetry ◽  
Exchange Method ◽  
Functionalized Graphene Oxide ◽  
Ct Analysis ◽  
Fire Retardant Properties ◽  
Layered Clay

Nanostructures are more and more evolved through extensive research on their functionalities; thus, the aim of this study was to obtain layered clay–graphene oxide nanohybrids with application as reinforcing agents in polyurea nanocomposites with enhanced thermal–mechanical and fire-retardant properties. Montmorillonite (MMT) was combined with graphene oxide (GO) and amine functionalized graphene oxide (GOD) through a new cation exchange method; the complex nanostructures were analyzed through FTIR and XPS to assess ionic interactions between clay layers and GO sheets by C1s deconvolution and specific C sp3, respective/ly, C-O secondary peaks appearance. The thermal decomposition of nanohybrids showed a great influence of MMT layers in TGA, while the XRD patterns highlighted mutual MMT and GO sheets crystalline-structure disruption by the d (002) shift 2θ = 6.29° to lower values. Furthermore, the nanohybrids were embedded in the polyurea matrix, and the thermo-mechanical analysis gave information about the stiffness of MMT–GO nanocomposites, while GOD insertion within the MMT layers resulted in a 30 °C improvement in the Tg of hard domains, as shown in the DSC study. The micro CT analysis show good dispersion of inorganic structures within the polyurea, while the SEM fracture images revealed smooth surfaces. Cone calorimetry was used to evaluate fire-retardant properties through limiting the oxygen index, and MMT–GOD based nanocomposites showed a 35.4% value.

scholarly journals Microscopy Methods for Biofilm Imaging: Focus on SEM and VP-SEM Pros and Cons

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 51
Author(s):  
Michela Relucenti ◽  
Giuseppe Familiari ◽  
Orlando Donfrancesco ◽  
Maurizio Taurino ◽  
Xiaobo Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Ion Beam ◽  
Ruthenium Red ◽  
Variable Pressure ◽  
Sem Images ◽  
Advantages And Disadvantages ◽  
Pros And Cons ◽  
Microscopy Techniques ◽  
Scanning Electron

Several imaging methodologies have been used in biofilm studies, contributing to deepening the knowledge on their structure. This review illustrates the most widely used microscopy techniques in biofilm investigations, focusing on traditional and innovative scanning electron microscopy techniques such as scanning electron microscopy (SEM), variable pressure SEM (VP-SEM), environmental SEM (ESEM), and the more recent ambiental SEM (ASEM), ending with the cutting edge Cryo-SEM and focused ion beam SEM (FIB SEM), highlighting the pros and cons of several methods with particular emphasis on conventional SEM and VP-SEM. As each technique has its own advantages and disadvantages, the choice of the most appropriate method must be done carefully, based on the specific aim of the study. The evaluation of the drug effects on biofilm requires imaging methods that show the most detailed ultrastructural features of the biofilm. In this kind of research, the use of scanning electron microscopy with customized protocols such as osmium tetroxide (OsO4), ruthenium red (RR), tannic acid (TA) staining, and ionic liquid (IL) treatment is unrivalled for its image quality, magnification, resolution, minimal sample loss, and actual sample structure preservation. The combined use of innovative SEM protocols and 3-D image analysis software will allow for quantitative data from SEM images to be extracted; in this way, data from images of samples that have undergone different antibiofilm treatments can be compared.

scholarly journals Effects of Graphene Nanoplatelets on Mechanical and Fire Performance of Flax Polypropylene Composites with Intumescent Flame Retardant

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4094
Author(s):  
Imran Ali ◽  
Nam Kyeun Kim ◽  
Debes Bhattacharyya
Keyword(s):  
Flame Retardant ◽  
Decomposition Rate ◽  
Natural Fiber ◽  
Fire Retardant ◽  
Graphene Nanoplatelets ◽  
Intumescent Flame Retardant ◽  
Fume Hood ◽  
Fire Dynamics ◽  
Polypropylene Composites ◽  
Set Up

The integration of intumescent flame-retardant (IFR) additives in natural fiber-based polymer composites enhances the fire-retardant properties, but it generally has a detrimental effect on the mechanical properties, such as tensile and flexural strengths. In this work, the feasibility of graphene as a reinforcement additive and as an effective synergist for IFR-based flax-polypropylene (PP) composites was investigated. Noticeable improvements in tensile and flexural properties were achieved with the addition of graphene nanoplatelets (GNP) in the composites. Furthermore, better char-forming ability of GNP in combination with IFR was observed, suppressing HRR curves and thus, lowering the total heat release (THR). Thermogravimetric analysis (TGA) detected a reduction in the decomposition rate due to strong interfacial bonding between GNP and PP, whereas the maximum decomposition rate was observed to occur at a higher temperature. The saturation point for the IFR additive along with GNP has also been highlighted in this study. A safe and effective method of graphene encapsulation within PP using the fume-hood set-up was achieved. Finally, the effect of flame retardant on the flax–PP composite has been simulated using Fire Dynamics Simulator.

The Photoluminescence Enhancement and Stability of Porous Silicon by Cathodic Reduction and Acid Treatment

2014 ◽  
Vol 887-888 ◽  
pp. 458-461
Author(s):  
Chang Qing Li ◽  
Kun Wang ◽  
Pei Jia Liu ◽  
Qi Ming
Keyword(s):  
Electron Microscope ◽  
Porous Silicon ◽  
Acid Treatment ◽  
Cathodic Reduction ◽  
Luminescence Properties ◽  
Sem Images ◽  
Photoluminescence Enhancement ◽  
The Stability ◽  
Scanning Electron ◽  
Cathode Reduction

Porous silicon (PSi) was fabricated by using electrochemical anodic etching method. Then acid treatment and cathode reduction treatment were employed to improve the luminescence properties and stability of PSi material. Photoluminescence (PL) measurements and scanning electron microscope (SEM) were used to observe the luminescence properties and microstructure of samples, respectively. The results of PL measurements showed that the PL intensity and the stability of luminescence of samples after cathodic reduction and acid treatment were significantly improved. The SEM images showed that the porosity of PSi may be increased through the cathodic reduction treated.

The Use of Sol-Gel Method for Obtaining Fire-Resistant Elastic Coatings on Cotton Fabrics

2021 ◽  
Vol 1038 ◽  
pp. 468-479
Author(s):  
Olga Skorodumova ◽  
Olena Tarakhno ◽  
Olena Chebotaryova ◽  
Oleg Bezuglov ◽  
Fatih Mehmet Emen
Keyword(s):  
Thin Layer ◽  
Fire Protection ◽  
Sol Gel ◽  
Fire Retardant ◽  
Cotton Fabrics ◽  
Covalent Bonds ◽  
Silica Coatings ◽  
Factors Influencing ◽  
Fire Retardant Properties ◽  
Main Factors

Based on the generalization of research results on the processes of obtaining SiO2 sols using tetraethoxysilane and ethyl silicates, the main factors influencing the elasticity of silica coatings on cotton fabrics and their fire-retardant properties are considered. The possibility of forming covalent bonds between the functional groups of cellulose, gel coating and flame retardant layer is considered, which explains the strong fixation of a thin layer of coating on the fibers of the fabric and improve its fire protection. The use of the developed compositions for fire-retardant elastic coatings based on ethyl silicate allows to increase the time of complete burning of cotton from 30s (untreated fabric) to 600s (treated with binary coating).

scholarly journals Possible source of ancient carbon in phytolith concentrates from harvested grasses

2012 ◽  
Vol 9 (5) ◽  
pp. 1873-1884 ◽  
Author(s):  
G. M. Santos ◽  
A. Alexandre ◽  
J. R. Southon ◽  
K. K. Treseder ◽  
R. Corbineau ◽  
...  
Keyword(s):  
Plant Tissue ◽  
Atmospheric Carbon Dioxide ◽  
Energy Dispersive Spectrometer ◽  
Nutrient Acquisition ◽  
Published Data ◽  
Plant Nutrient ◽  
Before Present ◽  
Sem Images ◽  
Carbon Dioxide Co2 ◽  
Scanning Electron

Abstract. Plants absorb and transport silicon (Si) from soil, and precipitation of Si within the living plants results in micrometric amorphous biosilica particles known as phytoliths. During phytolith formation, a small amount of carbon (<2%) can become occluded in the silica structure (phytC) and therefore protected from degradation by the environment after plant tissue decomposition. Since the major C source within plants is from atmospheric carbon dioxide (CO2) via photosynthesis, the current understanding is that the radiocarbon (14C) content of phytC should reflect the 14C content of atmospheric CO2 at the time the plant is growing. This assumption was recently challenged by 14C data from phytoliths extracted from living grasses that yielded ages of several thousand years (2–8 kyr BP; in radiocarbon years "Before Present" (BP), "Present" being defined as 1950). Because plants can take up small amounts of C of varying ages from soils (e.g., during nutrient acquisition), we hypothesized that this transported C within the plant tissue could be attached to or even embedded in phytoliths. In this work, we explore this hypothesis by reviewing previously published data on biosilica mineralization and plant nutrient acquisition as well as by evaluating the efficiency of phytolith extraction protocols from scanning electron microscope (SEM) images and energy dispersive spectrometer (EDS) analyses from harvested grasses phytolith concentrates. We show that current extraction protocols are inefficient since they do not entirely remove recalcitrant forms of C from plant tissue. Consequently, material previously measured as "phytC" may contain at least some fraction of soil-derived C (likely radiocarbon-old) taken up by roots. We also suggest a novel interpretation for at least some of the phytC – which enters via the root pathway during nutrient acquisition – that may help to explain the old ages previously obtained from phytolith concentrates.

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