Preparation and Anti-Flame Capability of Expandable Graphite

2012 ◽  
Vol 560-561 ◽  
pp. 779-783 ◽  
Author(s):  
Xiu Yan Pang ◽  
Ming Kai Song

Subscript textFeasible conditions to get flame retardant expandable graphite (EG) with low initiation expansion temperature and high dilatability were obtained through orthogonal test and single factor experiment. EG with initiation expansion temperature of 148 ±2 °C and expansion volume of 550 mL/g can be prepared according to the mass ratio of C : KMnO4 : 98% H2SO4 : Na4P2O7 = 1.0 : 0.4 : 5.0 : 0.6 (H2SO4 should be diluted to thSubscript texte mass concentration of 80% before intercalation reaction), the reaction time is 40 min at 40 °C. Addition of 30% of the prepared EG to Liner Low-Density Polyethylene (LLDPE) can improve its limiting oxygen index LOI from 17.5% to 29.4%, and the synergistic anti-flame LOI of 20% EG with 10 polyphosphate (APP II) can reach to 31.2%. TG and DTA analysis was completed to discuss the anti-flame mechanism.

2013 ◽  
Vol 11 (6) ◽  
pp. 953-959 ◽  
Author(s):  
Xiuyan Pang ◽  
Yu Tian ◽  
Mingwei Duan ◽  
Meng Zhai

AbstractTo get expandable graphite (EG) flame retardant for Liner Low-Density Polyethylene (LLDPE) with low initial expansion temperature and high dilatability, the effects of various factors on dilatability were investigated including the dosages of oxidant KMnO4, intercalating reagent H2SO4, assistant intercalating reagent acetic acid (HAc) and reaction temperature. Feasible conditions were obtained according to the results of L9 (34) experiments and single factor experiments. EG with an initial expansion temperature of 160°C and expansion volume of 460 mL g−1 could be prepared according to the mass ratio of material graphite C: KMnO4: 100% H2SO4: HAc = 1.0: 0.4: 5.0: 1.0 (H2SO4 should be diluted to the mass concentration of 75% before the intercalation reaction); the reaction time was 1.0 hour at 25°C. It was found that reaction temperature and H2SO4 dosage were the most important influence factors for dilatability. The limiting oxygen index could be improved to 28.1% by adding 30% of the prepared EG to LLDPE, and the synergistic anti-flame capability of 20% EG with 10% Ammonium polyphosphate (APP) (I) can reach to 33.9%. According to thermal gravimetric and differential thermal analysis results, 70% LLDPE /10% APP (I) /20% EG synergistic anti-flame system shows higher residual carbon and thermal stability.


2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Hongmei Zhao ◽  
Xiuyan Pang ◽  
Zhixiao Zhai

A kind of polyphosphate modified expandable graphite (EGp) was prepared in graphite oxidation and intercalation reaction with KMnO4 as oxidant, H2SO4 as intercalator, and sodium hexametaphosphate (SHMP) as assistant intercalator. The feasible mass ratio of C : KMnO4 : H2SO4 (98%) : SHMP was determined as 1.0 : 0.3 : 4.5 : 0.6, H2SO4 was diluted to 77 wt% before intercalation reaction, and the reaction lasted for 40 min at 40°C. Expanded volume and initial expansion temperature of the prepared EGp reached 600 mL/g (at 800°C) and 151°C, respectively. X-ray diffraction spectroscopy testified the intercalation and layer structure of EGp, and Fourier transform infrared spectroscopy illuminated the intercalated functional groups. Flame retardance of the prepared EGp and the referenced EG (with only H2SO4 as intercalator) for linear low density polyethylene (LLDPE) was also investigated. Addition of 30 wt% EGp to the polymer improved the limiting oxygen index (LOI) from 17.5 to 27.3%. On the other hand, the LOI of the same amount of the referenced EG was only 24.6%. Assistant intercalation of SHMP improved the dilatability and flame retardancy.


Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1801
Author(s):  
Rafał Oliwa ◽  
Joanna Ryszkowska ◽  
Mariusz Oleksy ◽  
Monika Auguścik-Królikowska ◽  
Małgorzata Gzik ◽  
...  

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.


Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 168 ◽  
Author(s):  
Pablo Acuña ◽  
Zhi Li ◽  
Mercedes Santiago-Calvo ◽  
Fernando Villafañe ◽  
Miguel Rodríguez-Perez ◽  
...  

Three types of expandable graphite (EG) differing in particle size and expansion volume, are compared as flame retardant additives to rigid polyurethane foams (RPUFs). In this paper we discuss microstructure, thermal stability, fire behavior, and compression performance. We find that ell size distributions were less homogeneous and cell size was reduced. Furthermore, thermal conductivity increased along with EG loading. Thermogravimetric analysis (TGA) showed that EG only increased residue yield differently. The results indicate that a higher expansion of EG increased the limiting oxygen index (LOI) value, whereas a bigger particle size EG improved the rating of the vertical burning test (UL94). Results from the cone calorimeter test showed that a bigger particle size EG effectively reduced peak of heat release rate (pHRR). Furthermore, a higher expansion, led to a decrease in smoke production (TSP). The combination of both characteristics gives extraordinary results. The physical–mechanical characterization of the EG/RPUF foams revealed that their compression performance decreased slightly, mostly due to the effect of a bigger size EG.


2011 ◽  
Vol 391-392 ◽  
pp. 204-208
Author(s):  
Xiao Ping Hu ◽  
Yu Yang Guo ◽  
Quan Min Xu ◽  
Hui Min Heng ◽  
Liang Jun Li

A novel intumescent flame retardant oligomer containing phosphorous-nitrogen structure (PSPTR) was synthesized and characterized by Fourier Transform Infrared (FTIR) and Mass Spectrometry (MS). The thermal behavior of PSPTR was investigated by thermogravimetric analysis (TGA). The TGA data shows that PSPTR has a high initial temperature of thermal degradation and a high char residue of 41.18wt% at 700 . A novel intumescent flame retardant (IFR) system, which is composed of PSPTR and novolac phenol (NP), was used to impart flame retardancy of ABS. The combustion behaviors of the ABS/IFR composites were investigated by Limiting Oxygen Index (LOI) and UL-94 tests. When the content of IFR (PSPTR:NP=1:1 mass ratio) is 30 wt%, the LOI value of ABS/IFR reaches 28.2, and the vertical burning test reaches UL-94 V-1 rating.


Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 127 ◽  
Author(s):  
Yu Sun ◽  
Yazhen Wang ◽  
Li Liu ◽  
Tianyuan Xiao

A 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) acrylate, (6-oxidodibenzo [c,e][1,2] oxaphosphinin-6-yl) methyl acrylate (DOPOAA), has been prepared. Copolymers of styrene (St) and DOPOAA were prepared by emulsion polymerization. The chemical structures of copolymers containing levels of DOPOAA were verified using Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The thermal properties and flame-retardant behaviors of DOPO-containing monomers and copolymers were observed using thermogravimetric analysis and micro calorimetry tests. From thermogravimetric analysis (TGA), it was found out that the T5% for decomposition of the copolymer was lower than that of polystyrene (PS), but the residue at 700 °C was higher than that of PS. The results from micro calorimetry (MCC) tests indicated that the rate for the heat release of the copolymer combustion was lower than that for PS. The limiting oxygen index (LOI) for combustion of the copolymer rose with increasing levels of DOPOAA. These data indicate that copolymerization of the phosphorus-containing flame-retardant monomer, DOPOAA, into a PS segment can effectively improve the thermal stability and flame retardancy of the copolymer.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2205
Author(s):  
Qian Li ◽  
Yujie Li ◽  
Yifan Chen ◽  
Qiang Wu ◽  
Siqun Wang

A novel liquid phosphorous-containing flame retardant anhydride (LPFA) with low viscosity was synthesized from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and methyl tetrahydrophthalic anhydride (MeTHPA) and further cured with bisphenol-A epoxy resin E-51 for the preparation of the flame retardant epoxy resins. Both Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS) and nuclear magnetic resonance (NMR) measurements revealed the successful incorporation of DOPO on the molecular chains of MeTHPA through chemical reaction. The oxygen index analysis showed that the LPFA-cured epoxy resin exhibited excellent flame retardant performance, and the corresponding limiting oxygen index (LOI) value could reach 31.2%. The UL-94V-0 rating was achieved for the flame retardant epoxy resin with the phosphorus content of 2.7%. With the addition of LPFA, the impact strength of the cured epoxy resins remained almost unchanged, but the flexural strength gradually increased. Meanwhile, all the epoxy resins showed good thermal stability. The glass transition temperature (Tg) and thermal decomposition temperature (Td) of epoxy resin cured by LPFA decreased slightly compared with that of MeTHPA-cured epoxy resin. Based on such excellent flame retardancy, low viscosity at room temperature and ease of use, LPFA showed potential as an appropriate curing agent in the field of electrical insulation materials.


2012 ◽  
Vol 441 ◽  
pp. 284-288
Author(s):  
Hong Lu ◽  
Yan Chen ◽  
Jin Ping Guan

In this paper, four kinds of silk georgettes with different density were chosen as samples. The flame retardant formaldehyde-free vinyl phosphate dimethyl-2-(methacryloyloxyethyl) phosphate (DMMEP) was grafted onto them by graft copolymerization technique. Some tests such as Limiting Oxygen Index (LOI), vertical flammability, wrinkle resistance and color fastness were examined. Through the discussion and analysis of the experiment results, the properties of original and treated fabrics were compared and suggestions were given for the flame retardant process and garment design.


2014 ◽  
Vol 1073-1076 ◽  
pp. 286-291
Author(s):  
Yong Zuo ◽  
Peng Jiang ◽  
Xiao Long Wang ◽  
Bin Fu ◽  
Xiao Long Yang ◽  
...  

The fermentation conditions of Bacterial Strain T2013 were studied. The fermentation conditions of T2013 were investigated with single-factor experiment. In addition to, the fermentation conditions were optimized through the orthogonal test. The results showed the highest production of blue pigment was obtained on condition that fermentation time was 2d, the liquid volume was 50ml in the 250ml shake-flask, the inoculum volume was 2%, the initial value of pH was 7.6, fermentation temperature was 37°C and the speed was 150r/min.The fermentation conditions of Bacterial Strain T2013 were preliminarily determined,whichprovides a theoretical basis for the industrial production of blue pigment.


2011 ◽  
Vol 175-176 ◽  
pp. 465-468 ◽  
Author(s):  
Lei Shi ◽  
Hua Wu Liu ◽  
Ping Xu ◽  
Dang Feng Zhao

Plain weave fabrics of polyacrylonitrile pre-oxidation yarns (PANOF) were prepared by small rapier loom. The flame retardation properties, mechanical properties and wear behaviors of PANOF plain weave fabrics were tested. The limiting oxygen index (LOI) of these PANOF plain weave fabric samples was 31%, which meets the criterion of flame-retardant fabrics. These fabrics neither melt nor shrunk when left in flame for a short period of time and the fabric structures were well maintained. Compared with flammable polyacrylonitrile fabrics, the polyacrylonitrile pre-oxidation fabrics exhibited excellent flame retardation properties, with satisfactory mechanical properties and comfortable handle.


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