scholarly journals Preparation of Ion-Exchanged TEMPO-Oxidized Celluloses as Flame Retardant Products

Molecules ◽  
2019 ◽  
Vol 24 (10) ◽  
pp. 1947
Author(s):  
Cunzhen Geng ◽  
Zhihui Zhao ◽  
Zhixin Xue ◽  
Peilong Xu ◽  
Yanzhi Xia
Keyword(s):  
Thermal Stability ◽  
Ion Exchange ◽  
Heat Release ◽  
Textile Industry ◽  
Large Scale ◽  
13C Nmr Spectroscopy ◽  
Commercial Application ◽  
Limiting Oxygen Index ◽  
13C Nuclear Magnetic Resonance ◽  
Microscale Combustion Calorimetry

Cellulose, as one of the most abundant natural biopolymers, has been widely used in textile industry. However, owing to its drawbacks of flammability and ignitability, the large-scale commercial application of neat cellulose is limited. This study investigated some TEMPO-oxidized cellulose (TOC) which was prepared by selective TEMPO-mediated oxidation and ion exchange. The prepared TOC was characterized by Fourier transform infrared (FT-IR) spectroscopy and solid-state 13C-nuclear magnetic resonance (13C-NMR) spectroscopy. The thermal stability and combustion performance of TOC were investigated by thermogravimetry analysis (TG), microscale combustion calorimetry (MCC) and limiting oxygen index (LOI). The results demonstrated that the thermal stability of TOC was less than that of the pristine material cellulose, but the peak of heat release rate (pHHR) and the total heat release (THR) of all TOC were significantly reduced. Additionally, the LOI values of all TOC products were much higher 25%. In summary, the above results indicated that the modified cellulose with carboxyl groups and metal ions by selective oxidation and ion exchange endows efficient flame retardancy.

ORGANOMETAL HALIDE PEROVSKITE PHOTOVOLTAICS: A DIAMOND IN THE ROUGH

NANO ◽  
2014 ◽  
Vol 09 (05) ◽  
pp. 1440002 ◽  
Author(s):  
MICHAEL GRÄTZEL ◽  
NAM-GYU PARK
Keyword(s):  
Thermal Stability ◽  
Large Scale ◽  
High Efficiency ◽  
Power Conversion ◽  
Perovskite Solar Cell ◽  
Commercial Application ◽  
The Sun ◽  
Metal Halide Perovskite ◽  
Organometal Halide Perovskite ◽  
Halide Perovskite

The sun finds a diamond in the rough, which is the organo-metal halide perovskite. Thanks to exceptional optoelectronic characteristics, solar cells employing perovskite demonstrated first a power conversion efficiency (PCE) of 9.7% in the middle of 2012, which rose steeply to an amazing 16% at the end of 2013. Perovskite-based photovoltaics have several advantages over conventional semiconductor p-n junction devices because high efficiency can be achieved from sub-micrometer-thick very cheap perovskite layers that can be formed by solution processing at temperatures below 150°C, rendering the perovskite solar cell versatile in its application. If photo- and thermal stability as well as tolerance to humidity can be achieved, commercial application on the large scale appear to be feasible.

Synergistic Effect between Modified Graphene Oxide and Ammonium Polyphosphate on Combustion Performance, Thermal Stability and Mechanical Properties of Polylactic Acid

2021 ◽  
Vol 36 (4) ◽  
pp. 367-378
Author(s):  
X.-Y. Pang ◽  
Y.-F. Meng ◽  
Y.-P. Xin ◽  
R. Chang ◽  
J.-Z. Xu
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Graphene Oxide ◽  
Heat Release ◽  
Polylactic Acid ◽  
Network Structure ◽  
Ammonium Polyphosphate ◽  
Limiting Oxygen Index ◽  
Combustion Performance ◽  
Modified Graphene Oxide

Abstract To improve the thermal stability, ZF-GO (graphene oxide (GO) modified by zinc ferrite (ZF)) is prepared. In view of the anti-dripping function of ZF-GO and flame retardant effect of ammonium polyphosphate (APP), the influence of ZF-GO, APP, mixture of ZF-GO and APP on combustion performance, thermal stability and mechanical properties of polylactic acid (PLA) is investigated. Results show that the modification of GO by ZF significantly improves the residue of ZFGO by 34.7%. The char-forming capability and unique network structure of ZF-GO prevent the melt dripping of PLA. Although APP can increase the limiting oxygen index of PLA, there is still melt dripping. The combination of ZF-GO and APP improves the residual yield of 94PLA/3ZF-GO/3APP by 4.3 times relative to pure PLA, and the UL-94 level reaches V-0. The two additives show synergistic char-forming effect, and there is both physical carbonization and chemical carbonization. The incorporated fillers can decrease the total heat release (THR) of PLA composites. Specifically, the THR and peak value of heat release rate of 94PLA/3ZF-GO/3APP decrease by 21.2% and 53.9%, respectively. For the PLA/ZF-GO/APP system, plenty of residues and the anti-dripping network structure are key factors to get good flame retardancy. Addition of ZFGO and APP reduces the tensile strength, but the tensile elongation of the modified PLA composites is improved. 94PLA/ 3ZF-GO/3APP shows good integrated performance.

scholarly journals Effects of chemical pre-treatment on structure and property of polyacrylonitrile based pre-oxidized fibers

2020 ◽  
Vol 15 ◽  
pp. 155892501989894
Author(s):  
Xiaolu Sun ◽  
Jiayin Song ◽  
Jin Zhang ◽  
Jingyan Liu ◽  
Huizhen Ke ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Heat Release ◽  
Flame Retardant ◽  
Oxygen Index ◽  
Energy Dispersive Spectrometer ◽  
Chemical Compositions ◽  
Limiting Oxygen Index ◽  
X Ray ◽  
Pre Treatment

Polyacrylonitrile-based pre-oxidized fibers with improved thermal stability, flame retardant, and mechanical properties were made from the pristine polyacrylonitrile fibers through chemical pretreatment followed by pre-oxidation in air. The morphological structure of the polyacrylonitrile-based pre-oxidized fibers was investigated by Fourier transfer infrared spectra, X-ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectrometer. The changes of characteristic functional groups and chemical compositions confirmed the successful modification of the polyacrylonitrile fibers during pre-treatment. The grooves and cracks on the surface of polyacrylonitrile-based pre-oxidized fibers were remarkably decreased in comparison with that of pristine polyacrylonitrile fibers. The evolution of crystalline structure of the polyacrylonitrile fibers proved the occurrence of cyclization reactions during pre-oxidation. Meanwhile, thermal stability, flame retardant, and mechanical properties of polyacrylonitrile-based pre-oxidized fibers were also investigated by thermogravimetric analyzer, oxygen index meter, micro combustion calorimeter, and single fiber tensile tester, respectively. The results demonstrated that the polyacrylonitrile-based pre-oxidized fibers initially pre-treated by hydroxylamine hydrochloride, followed by monoethanolamine, had a high limiting oxygen index of 40.1 and breaking strength of 2.03 cN/dtex. The peak of heat release rate and total heat release of polyacrylonitrile-based pre-oxidized fibers decreased significantly while its charred residues increased, contributing to the improved flame retardant property.

scholarly journals Thermal Properties of PEDOT-compl-PSS Sensor Yarns and Textile Reinforced Thermoplastic Composites

2019 ◽  
Vol 2 (2) ◽  
pp. 66-71
Author(s):  
Ivona Jerković ◽  
Ana Marija Grancarić ◽  
Clement Dufour ◽  
Francois Boussu ◽  
Vladan Končar
Keyword(s):  
Thermal Properties ◽  
Heat Release ◽  
Conductive Polymer ◽  
Thermoplastic Composites ◽  
Polymer Complex ◽  
Integrated Sensor ◽  
Limiting Oxygen Index ◽  
Smart Textile ◽  
Pyrolysis Residue ◽  
Microscale Combustion Calorimetry

Smart textile structures such as sensor yarns provide real possibility for in situ structural health monitoring of textile reinforced thermoplastic composites. In this work thermal properties of E-glass/polypropylene (GF/ PP) and E-glass/poly(N,N’-hexamethylene adipamide) (GF/PA66) sensor yarns based on conductive polymer complex [3,4(ethylenedioxy)thiophene]-compl-poly(4-vinylbenzenesulfonic acid) (PEDOT-compl-PSS) and related composites were studied. Thermogravimetric analysis (TGA), microscale combustion calorimetry (MCC) and limiting oxygen index (LOI) methods were used to detect thermal behaviour of these structures and effect of coatings applied. According to TGA, GF/PP sensor yarn started to decompose at higher temperature, 345 °C, and showed higher pyrolysis residue, 28 %, compared to GF/PA66 sensor yarn that started to decompose at 316 °C and had lower pyrolysis residue, 23 % . The MCC showed that Heat Release Rate peaks of GF/PP sensor yarn, 341 W/g, and GF/PA66 sensor yarn, 348 W/g, occurred at similar Heat Release Temperature, ~ 430 °C. The additional peak, 51 W/g, was detected for GF/PP sensor yarn at 493 °C. Finally, LOI 22 and LOI 23 were detected only for GF/PP and GF/PA66 composites with integrated sensor yarns.

Investigation on the effect of supported synergistic catalyst with intumescent flame retardant in polypropylene

2021 ◽  
Vol 41 (4) ◽  
pp. 281-288
Author(s):  
Hongmei Peng ◽  
Qi Yang
Keyword(s):  
Heat Release ◽  
Flame Retardant ◽  
Flame Retardancy ◽  
Flame Retardants ◽  
Supported Catalyst ◽  
Intumescent Flame Retardant ◽  
Limiting Oxygen Index ◽  
Polypropylene Composites ◽  
Cone Calorimeter Test ◽  
Microscale Combustion Calorimetry

Abstract In this paper, cerium nitrate supported silica was prepared as a new type of catalytic synergist to improve the flame retardancy in polypropylene. When 1% of Ce(NO3)2 supported SiO2 was added, the vertical combustion performance of UL-94 of polypropylene composites was improved to V-0, the limiting oxygen index (LOI) was increased to 33.5. From the thermogravimetric analysis (TGA), the residual carbon of C and D was increased by about 6% at high temperature compared with B. When adding supported catalyst, the heat release rate (HRR) and total heat release (THR) were significantly reduced according to the microscale combustion calorimetry (MCC), the HRR of sample E with 2% synergist was the lowest. The combustion behaviors of intumescent flame retardant sample B and sample D were analyzed by cone calorimeter test (CCT), the HRR of sample D with supported synergist was significantly reduced, and the PHRR decreased from 323 kW/m2 to 264 kW/m2. The morphologies of the residue chars after vertical combustion of polypropylene composites observed by scanning electron microscopy (SEM) gave positive evidence that the supported synergist could catalyze the decomposition of intumescent flame retardants into carbon, which was the main reason for improving the flame retardancy of materials.

Synergistic effects of red phosphorus masterbatch with expandable graphite on the flammability and thermal stability of polypropylene/thermoplastic polyurethane blends

2019 ◽  
Vol 28 (3) ◽  
pp. 209-219 ◽  
Author(s):  
Na Wang ◽  
Lingtong Li ◽  
Yang Xu ◽  
Kun Zhang ◽  
Xiaolang Chen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Heat Release ◽  
Flame Retardant ◽  
Synergistic Effects ◽  
Thermoplastic Polyurethane ◽  
Expandable Graphite ◽  
Gravimetric Analysis ◽  
Red Phosphorus ◽  
Limiting Oxygen Index ◽  
Ul 94

The flammability characterization and synergistic effects of red phosphorus masterbatch (RPM) with expandable graphite (EG) in flame-retardant polypropylene (PP)/thermoplastic polyurethane (TPU) composites are investigated by limiting oxygen index, UL-94 testing, cone calorimeter tests, thermal gravimetric analysis, Fourier transform infrared (FTIR), and scanning electron microscopy. The results show that the flame retardancy of PP/TPU/EG/RPM composites is greatly influenced by RPM. The synergistic effects between RPM and EG take place in the flame-retardant composites. The presence of RPM with EG decreases significantly the heat release rates and total heat release, and UL-94 V-0 rating is achieved when suitable amount of RPM substitutes for EG in the PP/TPU/EG/RPM composites. The T onset and T 10 wt% of the composites are improved because of the presence of RPM. The FTIR spectra show that the incorporation of RPM improves the thermo-oxidative stability of PP/TPU at higher temperatures. The morphological observations indicate the reinforcement of thermal stability, and flame-retardant performance is attributed to the compact and stable char layers promoted by RPM with EG acted as an effective heat barrier and thermal insulation.

Impact of graphene oxide on epoxy resin characteristics

2020 ◽  
pp. 095400832094392
Author(s):  
Maziyar Sabet ◽  
Hassan Soleimani ◽  
Seyednooroldin Hosseini ◽  
Erfan Mohammadian
Keyword(s):  
Thermal Stability ◽  
Graphene Oxide ◽  
Heat Release ◽  
Fire Resistance ◽  
Fire Retardant ◽  
Polymer Chains ◽  
Limiting Oxygen Index ◽  
Limited Mobility ◽  
Smoke Production ◽  
Smoke Density

The incorporation of a small part of graphene oxide (GO) offers an appropriate fire retardant for thermally conductive epoxy (EP) resin composites, which is verified by the upper limiting oxygen index of 24.5% and other standard flame-retardant tests. The smoke production rate, total smoke production (TSP), and the smoke density of EP composites were reduced with additional GO. The increased efficiency of fire resistance and smoke suppression is primarily due to the formation of physical barrier and compactness of the developed GO char layers, serving as an effective barrier layer that increases the fire resistance, and the thermal steadiness of the char layers derives from the effect of GO inclusion. The barrier impact of GO and the limited mobility of polymer chains are crucial factors in increasing thermal stability and reduction of generating dangerous carbon monoxide during burns. The thermal stability increased and the peak heat release rate, total heat release, TSP, and the largest smoke density value reduced to 52.5%, 43.6%, 33.9%, and 44.2%, correspondingly, compared with pure EP. The tensile strength and elongation at break of EP composites were enhanced by 23% and 8.4% compared with pure EP, respectively.

scholarly journals Effects of Chemically Treated Eucalyptus Fibers on Mechanical, Thermal and Insulating Properties of Polyurethane Composite Foams

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1781 ◽  
Author(s):  
Sylwia Członka ◽  
Anna Strąkowska ◽  
Piotr Pospiech ◽  
Krzysztof Strzelec
Keyword(s):  
Thermal Stability ◽  
Heat Release ◽  
Polyurethane Foams ◽  
Mechanical And Thermal Properties ◽  
Flame Resistance ◽  
Cone Calorimetry ◽  
Limiting Oxygen Index ◽  
Polyurethane Composite ◽  
Surface Modified ◽  
The Impact

In this work, rigid polyurethane (PUR) foams were prepared by incorporating 2 wt% of eucalyptus fibers. The eucalyptus fibers were surface-modified by maleic anhydride, alkali, and silane (triphenylsilanol) treatment. The impact of the modified eucalyptus fibers on the mechanical, thermal, and fire performances of polyurethane foams was analyzed. It was observed that the addition of eucalyptus fibers showed improved mechanical and thermal properties and the best properties were shown by silane-treated fibers with a compressive strength of 312 kPa and a flexural strength of 432 kPa. Moreover, the thermal stability values showed the lowest decline for polyurethane foams modified with the silane-treated fibers, due to the better thermal stability of such modified fibers. Furthermore, the flame resistance of polyurethane foams modified with the silane-treated fibers was also the best among the studied composites. A cone calorimetry test showed a decrease in the peak of heat release from 245 to 110 kW∙m−2 by the incorporation of silane-treated fibers. Furthermore, total heat release and total smoke release were also found to decrease remarkably upon the incorporation of silane-treated fibers. The value of limiting oxygen index was increased from 20.2% to 22.1%. Char residue was also found to be increased from 24.4% to 28.3%. It can be concluded that the application of chemically modified eucalyptus fibers has great potential as an additive to incorporate good mechanical, thermal, and fire properties in rigid polyurethane foams.

scholarly journals Surface Coating for Flame Retardancy and Pyrolysis Behavior of Polyester Fabric Based on Calcium Alginate Nanocomposites

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 875 ◽  
Author(s):  
Zhenhui Liu ◽  
Jiao Li ◽  
Xihui Zhao ◽  
Zichao Li ◽  
Qun Li
Keyword(s):  
Thermal Stability ◽  
Flame Retardancy ◽  
Textile Industry ◽  
Calcium Alginate ◽  
Polyester Fabric ◽  
Gas Chromatography Mass Spectrometry ◽  
Calcium Borate ◽  
Cone Calorimetry ◽  
Pyrolysis Gas ◽  
Limiting Oxygen Index

A polyester fabric, coated with calcium alginate and nano-calcium borate composites (CAB-PL), was fabricated by a post-cross-linking method, with remarkable improvement of flame retardancy and thermal stability, as compared with the original polyester fabric (PL). The mechanical properties of CAB-PL and PL were studied, and characterizations and tests including Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM), limiting oxygen index (LOI), cone calorimetry (CONE) and thermogravimetric analysis (TGA) were employed to evaluate the flame retardancy and thermostability. The test results of CAB-PL showed excellent mechanical strength and anti-dripping properties. In comparison with PL, TGA results indicate that the presence of surface-coated composites produced more char residue and can effectively inhibit the heat transmission, and the LOI value of CAB-PL was improved from 25 to 33. Moreover, CONE results show that 88.65% reduction of total smoke release (TSR) values was induced by the presence of CAB. In addition, the possible pyrolysis mechanisms for CAB-PL have been proposed based on the results of pyrolysis-gas chromatography–mass spectrometry (Py-GC-MS) analysis. The combined results can provide useful information for understanding the flame retardant mechanisms of alginates as well. In summary, polyester fabric was upgraded by coating it with the calcium alginate/nano-calcium borate, thus achieving extraordinary flame retardancy and thermal stability for various applications within the textile industry.

Biomass Chitosan-Induced Fe3O4 Functionalized Halloysite Nanotube Composites: Preparation, Characterization and Flame-Retardant Performance

NANO ◽  
2019 ◽  
Vol 14 (12) ◽  
pp. 1950154 ◽  
Author(s):  
Mengmeng Zhang ◽  
Yamin Cheng ◽  
Zhiwei Li ◽  
Xiaohong Li ◽  
Laigui Yu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Heat Release ◽  
Flame Retardant ◽  
Combustion Process ◽  
Three Dimensional ◽  
Halloysite Nanotubes ◽  
Limiting Oxygen Index ◽  
Degradation Temperature ◽  
Cone Calorimeter Test ◽  
Ep Matrix

An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe3O4, is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe3O[Formula: see text] playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe3O4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe3O4 is significantly improved by [Formula: see text]C relative to pure EP, and the residual carbon yield under air atmosphere is 8.8[Formula: see text]wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe3O4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe3O4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe3O4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.

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