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Charles A. Wilkie - One of the best experts on this subject based on the ideXlab platform.
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Polystyrene- and poly (methyl methacrylate)-organoclay nanocomposites using a one-chain benzimidazolium surfactant
Polymer Degradation and Stability, 2013Co-Authors: Jianxiang Feng, Charles A. WilkieAbstract:In this paper, the synthesis of a one-chain benzimidazolium surfactant is accomplished and polystyrene (PS) and poly(methyl methacrylate) (PMMA) nanocomposites with organoclay modified by the above surfactant are prepared by melt blending. XRD, TEM, TGA and Cone Calorimetry are employed to evaluate the dispersion of the clay in the polymer matrices, thermal stability and fire behavior. TEM results show that the clay disperses more uniformly in the PMMA matrix than in PS. Both polymer nanocomposites exhibit enhanced thermal stability. From Cone Calorimetry, substantial reduction of heat release rates is obtained at 3wt% and 5wt% of clay from polystyrene and a more remarkable reduction in PMMA.
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Fire performance of flame retardant polypropylene and polystyrene composites screened with microscale combustion Calorimetry
Polymers for Advanced Technologies, 2010Co-Authors: Hongdian Lu, Charles A. WilkieAbstract:Flame retardant polypropylene (PP) and polystyrene (PS) materials were prepared by the incorporation of decabromodiphenyl oxide and Sb2O3 in addition to nanoparticles, montmorillonite clay, and carbon nanotubes (CNTs). Their fire performance was screened with microscale combustion Calorimetry (MCC) as well as evaluated by Cone Calorimetry. The decabromodiphenyl oxide–Sb2O3 system exhibited better efficiency in reducing the peak heat release rate (PHRR) of PP compared to PS in the MCC, whereas the trend was the opposite in Cone Calorimetry. Introduction of clay or CNTs to the decabromodiphenyl oxide–Sb2O3 system was beneficial in reducing the PHRR of both composites in Cone Calorimetry; however, a reduction in the PHRR in the MCC was only observed in the PS composites. The thermogravimetric analysis (TGA) studies revealed that the fire results from the MCC for the two types of composites were strongly correlated with their thermal degradation traces. There were poor relationships between the parameters of MCC and Cone Calorimetry, but good correlation between the temperature difference of the first and second peak of mass loss rate in the TGA, temperature at the PHRR in the MCC, and fire performance index in the Cone Calorimetry. Copyright © 2010 John Wiley & Sons, Ltd.
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Study on Intumescent Flame Retarded Polystyrene Composites with Improved Flame Retardancy
Polymer Degradation and Stability, 2010Co-Authors: Hongdian Lu, Charles A. WilkieAbstract:The flame retardancy and thermal stability of ammonium polyphosphate/tripentaerythritol (APP/TPE) intumescent flame retarded polystyrene composites (PS/IFR) combined with organically-modified layered inorganic materials (montmorillonite clay and zirconium phosphate), nanofiber (multiwall carbon nanotubs), nanoparticle (Fe2O3) and nickel catalyst were evaluated by Cone Calorimetry, microscale combustion Calorimetry (MCC) and thermogravimetric analysis (TGA). Cone Calorimetry revealed that a small substitution of IFR by most of these fillers (≤2%) imparted substantial improvement in flammability performance. The montmorillonite clay exhibited the highest efficiency in reducing the peak heat release rate of PS/IFR composite, while zirconium phosphate modified with C21H26NClO3S exhibited a negative effect. The yield and thermal stability of the char obtained from TGA correlated well with the reduction in the peak heat release rate in the Cone calorimeter. Since intumesence is a condensed-phase flame process, the MCC results showed features different from those obtained from the Cone calorimeter.
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The effects of intralayer metal composition of layered double hydroxides on glass transition, dispersion, thermal and fire properties of their PMMA nanocomposites
Thermochimica Acta, 2009Co-Authors: Charles Manzi-nshuti, Shengpei Su, Dan Chen, Charles A. WilkieAbstract:Abstract A series of aluminum-containing layered double hydroxides (LDHs), containing Mg, Ca, Co, Ni, Cu and Zn as the divalent metals, have been prepared by the co-precipitation method and used to prepare nanocomposites of PMMA by in situ bulk polymerization. The additives were characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy (XRD) and thermogravimetric analysis while the polymer composites were characterized by XRD, transmission electron microscopy, differential scanning Calorimetry and Cone Calorimetry. Polymerization of methyl methacrylate in the presence of these undecenoate LDHs results in composites with enhanced thermal stability. The glass transition temperatures of the composites and the pristine polymers are found to be around 110 °C; this suggests that the presence of these additives has little effect on the polymer. It is found that the additive composition and the dispersion state of LDHs agglomerates in the polymer matrix influence the fire properties of composites as measured by Cone Calorimetry.
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High‐throughput method for estimating the time to sustained ignition of polystyrene–clay nanocomposites based on thermogravimetric analysis
Polymers for Advanced Technologies, 2009Co-Authors: Marius C. Costache, Charles A. WilkieAbstract:Polymer-modified clay nanocomposites were prepared by melt blending and the time to ignition was measured by Cone Calorimetry at various heat fluxes. Based on these experimental results, a critical mass flux and critical percentage mass loss (pmlcrit) for piloted ignition were identified and validated for both virgin polystyrene and its composites, across a wide range of heating fluxes. Based on the assumption that the polymer degradation kinetics in the heating segment of the Cone Calorimetry (up to the moment of ignition) and thermogravimetry experiments are similar, and using the pmlcrit, we hypothesized that the onset degradation temperature of the TGA samples (defined here as the temperature at pmlcrit) could be used to estimate the time to sustained ignition in Cone Calorimetry experiments. The onset degradation temperature and the time to sustained ignition showed a good correlation, regardless of the heating flux used in Cone Calorimetry experiments. Copyright © 2009 John Wiley & Sons, Ltd.
Rongjie Yang - One of the best experts on this subject based on the ideXlab platform.
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using tga ftir tga ms and Cone Calorimetry to understand thermal degradation and flame retardancy mechanism of polycarbonate filled with solid bisphenol a bis diphenyl phosphate and montmorillonite
Polymer Degradation and Stability, 2012Co-Authors: Jie Feng, Jianxin Du, Rongjie YangAbstract:Investigation of thermal degradation is essential for understanding flame retardancy mechanism and further tailoring of materials. In this work, polycarbonate was compounded with solid bisphenol A bis(diphenyl phosphate) (S-BDP) and organo-montmorillonite (OMMT) to form a nanocomposite with mainly intercalated and partially exfoliated morphology, and the main flame retardancy activity of the nanocomposite was shown to be in the condensed phase as revealed by Cone Calorimetry, thermogravimetric analysis coupled with Fourier transform infrared spectrometry (TGA/FTIR) and thermogravimetric analysis coupled with mass spectrometry (TGA/MS). Although the main gaseous pyrolysis products of polycarbonate can't be greatly altered by S-BDP and OMMT, carbonate linkage would be stabilized and vigorous decomposition at higher temperature would be delayed, thereby char residue formation could be promoted. S-BDP also shows slight gaseous phase effect as proved by the detection of phosphorus–oxygen species in TGA/MS. Moreover, the relatively enhanced evolution of PO radicals in the sample filled with only S-BDP suggests that S-BDP alone exhibits a slightly stronger gaseous phase effect than the combination of S-BDP and OMMT. This enhanced condensed phase effect of S-BDP in the presence of OMMT could be associated with the delayed vigorous decomposition at higher temperature due to the barrier effect of OMMT. The peak heat release rate of polycarbonate could not be significantly reduced by substituting S-BDP with OMMT, yet it would prolong the time to peak heat release rate and reduce the smoke toxicity with a smaller release of carbon monoxide. The reduced carbon monoxide release was probably caused by further oxidation of carbon monoxide in the hotter char surface due to the barrier effect of OMMT.
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Using TGA/FTIR TGA/MS and Cone Calorimetry to understand thermal degradation and flame retardancy mechanism of polycarbonate filled with solid bisphenol A bis(diphenyl phosphate) and montmorillonite
Polymer Degradation and Stability, 2012Co-Authors: Jie Feng, Jianxin Du, Rongjie YangAbstract:Investigation of thermal degradation is essential for understanding flame retardancy mechanism and further tailoring of materials. In this work, polycarbonate was compounded with solid bisphenol A bis(diphenyl phosphate) (S-BDP) and organo-montmorillonite (OMMT) to form a nanocomposite with mainly intercalated and partially exfoliated morphology, and the main flame retardancy activity of the nanocomposite was shown to be in the condensed phase as revealed by Cone Calorimetry, thermogravimetric analysis coupled with Fourier transform infrared spectrometry (TGA/FTIR) and thermogravimetric analysis coupled with mass spectrometry (TGA/MS). Although the main gaseous pyrolysis products of polycarbonate can't be greatly altered by S-BDP and OMMT, carbonate linkage would be stabilized and vigorous decomposition at higher temperature would be delayed, thereby char residue formation could be promoted. S-BDP also shows slight gaseous phase effect as proved by the detection of phosphorus–oxygen species in TGA/MS. Moreover, the relatively enhanced evolution of PO radicals in the sample filled with only S-BDP suggests that S-BDP alone exhibits a slightly stronger gaseous phase effect than the combination of S-BDP and OMMT. This enhanced condensed phase effect of S-BDP in the presence of OMMT could be associated with the delayed vigorous decomposition at higher temperature due to the barrier effect of OMMT. The peak heat release rate of polycarbonate could not be significantly reduced by substituting S-BDP with OMMT, yet it would prolong the time to peak heat release rate and reduce the smoke toxicity with a smaller release of carbon monoxide. The reduced carbon monoxide release was probably caused by further oxidation of carbon monoxide in the hotter char surface due to the barrier effect of OMMT.
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flame retardant synergism of gup and boric acid by Cone Calorimetry
Journal of Applied Polymer Science, 2006Co-Authors: Shousheng Yang, Rongjie YangAbstract:Wood was treated with a new composite flame retardant (FRW), with its components guanyl urea phosphate (GUP) and boric acid (BA) to impart flame retardance. The flame retarding behavior of these samples was valued by Cone calorimeter. The flammability parameters, including rate of heat release (RHR), total heat release (THR), effective heat of combustion (EHC), total mass loss (TML) and mass loss rate (MLR), yield of CO, smoke production rate (SPR), and specific extinction area (SEA) were recorded simultaneously. By analyzing these data, it was concluded that most combustion parameters of wood decreased by the treatment, especially for the FRW treatment, considerably decreased while the date for wood treated with GUP or boric acid decreased much less for the similar upload, which indicated a synergistic effect of flame retardance and suppressing smoke between GUP and boric acid in FRW, which has not been reported in other researches until now. Meanwhile, the probable flame retardation mechanism was proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5522–5527, 2006
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synergism of gup and boric acid characterized by Cone Calorimetry and thermogravimetry
Journal of Fire Sciences, 2006Co-Authors: Rongjie YangAbstract:Wood is treated with a new composite flame retardant, whose components guanyl urea phosphate (GUP) and boric acid (BA) impart flame retardance. The flame retarding behavior of these samples is measured by Cone calorimeter. The thermal behavior of samples has been studied by differential thermogravimetry (DTG) and thermogravimetry (TG) in air. The activation energies for different stages of thermal degradation are obtained following the method of Broido, A. (1969). J. Polym. Sci., Part 2, 7: 1761. It is found that the combustion parameters of wood, including rate of heat release (RHR) and total heat release (THR) are decreased considerably by the treatment, especially for wood treated with the composite flame retardant of wood (FRW) because of a strong synergistic effect of flame retardance between GUP and boric acid. The mechanism of synergism is explained by analyzing the TG data. The GUP can accelerate dehydration and carbonization while BA can relatively increase thermal stabilization of wood. Their synthetical actions result in more char and less flammable volatile products, obtaining good flame retardance. Language: en
Rui Zhang - One of the best experts on this subject based on the ideXlab platform.
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flammability and thermal stability studies of styrene butyl acrylate copolymer graphite oxide nanocomposite
Polymer Degradation and Stability, 2004Co-Authors: Rui Zhang, Yuan Hu, Jiayan Xu, Zuyao ChenAbstract:Styreneebutyl acrylate copolymer (SteBA)/graphite oxide (GO) nanocomposites were prepared via exfoliationeadsorption with monomer followed by in situ emulsion polymerization. The structure of the nanocomposites was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Both differential scanning Calorimetry (DSC) measurements and Cone Calorimetry experiments were carried out to evaluate their thermal stability and flammability properties. The Cone Calorimetry data showed that the peak heat release rate (HRR) value is reduced remarkably by 45% in an SteBA/GO nanocomposite with a GO content of only 1 wt%. The result suggests that the addition of GO even in 1 wt% content can greatly decrease the heat and smoke release rate of the SteBA/GO nanocomposites, and can increase their thermal decomposition temperature (Td) slightly. However, no effect of GO content on the reduction of HRR and THR in nanocomposites is apparent. 2004 Elsevier Ltd. All rights reserved.
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Flammability and thermal stability studies of styrene–butyl acrylate copolymer/graphite oxide nanocomposite
Polymer Degradation and Stability, 2004Co-Authors: Rui Zhang, Yuan Hu, Jiayan Xu, Zuyao ChenAbstract:Styreneebutyl acrylate copolymer (SteBA)/graphite oxide (GO) nanocomposites were prepared via exfoliationeadsorption with monomer followed by in situ emulsion polymerization. The structure of the nanocomposites was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Both differential scanning Calorimetry (DSC) measurements and Cone Calorimetry experiments were carried out to evaluate their thermal stability and flammability properties. The Cone Calorimetry data showed that the peak heat release rate (HRR) value is reduced remarkably by 45% in an SteBA/GO nanocomposite with a GO content of only 1 wt%. The result suggests that the addition of GO even in 1 wt% content can greatly decrease the heat and smoke release rate of the SteBA/GO nanocomposites, and can increase their thermal decomposition temperature (Td) slightly. However, no effect of GO content on the reduction of HRR and THR in nanocomposites is apparent. 2004 Elsevier Ltd. All rights reserved.
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preparation and combustion properties of flame retardant styrene butyl acrylate copolymer graphite oxide nanocomposites
Macromolecular Materials and Engineering, 2004Co-Authors: Rui Zhang, Weicheng Fan, Yuan Hu, Jiayan Xu, Zuyao Chen, Qinan WangAbstract:Styrene-butyl acrylate copolymer (St-BA)/graphite oxide (GO) nanocomposites and St-BA/GO/MPP [melamine poly(metaphosphate)] composites were prepared via an intercalation process by the ball-milling method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microanalyzer (SEM). Cone Calorimetry experiments were carried out to evaluate their flammability. The Cone Calorimetry data suggested that the addition of GO can decrease the heat release rate of St-BA copolymers significantly. Furthermore, there was also a synergistic effect on the fire retardant property by the combination of GO and MPP. However, no prominent effect of the GO content on the reduction of peak heat release rate (HRR) in nanocomposites could be found.
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Preparation and Combustion Properties of Flame Retardant Styrene‐Butyl Acrylate Copolymer/Graphite Oxide Nanocomposites
Macromolecular Materials and Engineering, 2004Co-Authors: Rui Zhang, Yuan Hu, Jiayan Xu, Zuyao Chen, Qinan WangAbstract:Styrene-butyl acrylate copolymer (St-BA)/graphite oxide (GO) nanocomposites and St-BA/GO/MPP [melamine poly(metaphosphate)] composites were prepared via an intercalation process by the ball-milling method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microanalyzer (SEM). Cone Calorimetry experiments were carried out to evaluate their flammability. The Cone Calorimetry data suggested that the addition of GO can decrease the heat release rate of St-BA copolymers significantly. Furthermore, there was also a synergistic effect on the fire retardant property by the combination of GO and MPP. However, no prominent effect of the GO content on the reduction of peak heat release rate (HRR) in nanocomposites could be found.
Zuyao Chen - One of the best experts on this subject based on the ideXlab platform.
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Magnesium hydroxide sulfate hydrate whisker flame retardant polyethylene/montmorillonite nanocomposites
Journal of Materials Science, 2006Co-Authors: Hongdian Lu, Yuan Hu, Junfeng Xiao, Zhengzhou Wang, Zuyao ChenAbstract:Flame retardant maleated polyethylene/magnesium hydroxide sulfate hydrate whisker (MAPE/MHSH) composites containing organo-modified montmorillonite (OMT) were prepared by direct melt intercalation. Their morphology, combustion behaviour and thermal stability were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), Cone Calorimetry and thermogravimetric analyses (TGA). The exfoliation of silicate layers within MAPE has been verified by XRD and TEM images. Cone Calorimetry results indicated that a synergistic flame retardant effect on reducing heat release rate (HRR) occurred when MHSH and OMT were both present in nanocomposite. The reduction in HRR improved as the mass fraction of OMT was increased from 2 to 10 wt%, but there was little improvement above 5 wt% OMT loading level. TGA profiles of the nanocomposites revealed that the thermodegradation stability of the nanocomposites decreased as the OMT fraction increased from 2 to 10 wt%.
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Influence of gamma irradiation on high density polyethylene/ethylene‐vinyl acetate/clay nanocomposites
Polymers for Advanced Technologies, 2004Co-Authors: Hongdian Lu, Yuan Hu, Qinghong Kong, Zuyao ChenAbstract:The study of high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA)/and organically-modified montmorillonite (OMT) nanocomposites prepared by melt intercalation followed by exposure to gamma-rays have been carried out. The morphology and properties of the nanocomposites were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Cone Calorimetry. The purpose of the study focuses on the influence of gamma irradiation on the morphology, thermal stability and flammability properties of the nanocomposites. XRD studies and TEM images verified that the ordered intercalated nanomorphology of the nanocomposites was not disturbed by gamma irradiation. TGA data showed that the nano-dispersion of clay throughout the polymer inhibited the irradiation degradation of HDPE/EVA blend, which led to the nanocomposites exhibiting superior irradiation-resistant properties than that of the pure blend. Cone Calorimetry results indicated that the improvement in heat release rate (HRR) for irradiated HDPE/EVA blend was suppressed efficiently when clay was present. Increasing clay loading from 2 to 10% was beneficial by improving the flammability properties of the nanocomposites, but promoted a rapid increase in the sub-peak HRR at high irradiation dose level. Copyright © 2004 John Wiley & Sons, Ltd.
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flammability and thermal stability studies of styrene butyl acrylate copolymer graphite oxide nanocomposite
Polymer Degradation and Stability, 2004Co-Authors: Rui Zhang, Yuan Hu, Jiayan Xu, Zuyao ChenAbstract:Styreneebutyl acrylate copolymer (SteBA)/graphite oxide (GO) nanocomposites were prepared via exfoliationeadsorption with monomer followed by in situ emulsion polymerization. The structure of the nanocomposites was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Both differential scanning Calorimetry (DSC) measurements and Cone Calorimetry experiments were carried out to evaluate their thermal stability and flammability properties. The Cone Calorimetry data showed that the peak heat release rate (HRR) value is reduced remarkably by 45% in an SteBA/GO nanocomposite with a GO content of only 1 wt%. The result suggests that the addition of GO even in 1 wt% content can greatly decrease the heat and smoke release rate of the SteBA/GO nanocomposites, and can increase their thermal decomposition temperature (Td) slightly. However, no effect of GO content on the reduction of HRR and THR in nanocomposites is apparent. 2004 Elsevier Ltd. All rights reserved.
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Flammability and thermal stability studies of styrene–butyl acrylate copolymer/graphite oxide nanocomposite
Polymer Degradation and Stability, 2004Co-Authors: Rui Zhang, Yuan Hu, Jiayan Xu, Zuyao ChenAbstract:Styreneebutyl acrylate copolymer (SteBA)/graphite oxide (GO) nanocomposites were prepared via exfoliationeadsorption with monomer followed by in situ emulsion polymerization. The structure of the nanocomposites was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Both differential scanning Calorimetry (DSC) measurements and Cone Calorimetry experiments were carried out to evaluate their thermal stability and flammability properties. The Cone Calorimetry data showed that the peak heat release rate (HRR) value is reduced remarkably by 45% in an SteBA/GO nanocomposite with a GO content of only 1 wt%. The result suggests that the addition of GO even in 1 wt% content can greatly decrease the heat and smoke release rate of the SteBA/GO nanocomposites, and can increase their thermal decomposition temperature (Td) slightly. However, no effect of GO content on the reduction of HRR and THR in nanocomposites is apparent. 2004 Elsevier Ltd. All rights reserved.
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preparation and combustion properties of flame retardant styrene butyl acrylate copolymer graphite oxide nanocomposites
Macromolecular Materials and Engineering, 2004Co-Authors: Rui Zhang, Weicheng Fan, Yuan Hu, Jiayan Xu, Zuyao Chen, Qinan WangAbstract:Styrene-butyl acrylate copolymer (St-BA)/graphite oxide (GO) nanocomposites and St-BA/GO/MPP [melamine poly(metaphosphate)] composites were prepared via an intercalation process by the ball-milling method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microanalyzer (SEM). Cone Calorimetry experiments were carried out to evaluate their flammability. The Cone Calorimetry data suggested that the addition of GO can decrease the heat release rate of St-BA copolymers significantly. Furthermore, there was also a synergistic effect on the fire retardant property by the combination of GO and MPP. However, no prominent effect of the GO content on the reduction of peak heat release rate (HRR) in nanocomposites could be found.
Yuan Hu - One of the best experts on this subject based on the ideXlab platform.
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Synergistic Effects of Nanoporous Nickel Phosphates VSB-1 on Intumescent Flame Retardant Polypropylene Composites
Advanced Materials Research, 2014Co-Authors: Chao Peng, Qi Lin He, Yuan HuAbstract:Nanoporous nickel phosphates (VSB-1) was synthesized by hydrothermal method. Then VSB-1 was added to the ammonium polyphosphate and pentaerythritol system in polypropylene (PP) matrix.The synergistic effect of VSB-1 with intumescent flame retardants (IFR) was studied by Cone Calorimetry test. The results of Cone Calorimetry show that heat release rate peak (pHRR) and total heat release (THR) of intumescent flame retardant PP with 2wt% VSB-1 decrease remarkably compared with that of without VSB-1. The pHRR and THR decrease respectively from 1140 to 286.0 kW/m2, and from 96.0 to 63.2 MJ/m2.
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Synergistic Effect of Novel Synergists–Transition Metal Ion-incorporated Nickel Phosphates with Intumescent Flame Retardants in Polypropylene
Journal of Macromolecular Science Part A, 2009Co-Authors: Lei Song, Yuan Hu, Jing Zhan, Lijuan ChenAbstract:The two kinds of transition metal ion-incorporated nickel phosphates (TMIVSB-1) were synthesized by the hydrothermal method. The flame retardancy and thermal behavior of intumescent flame retardants (IFR), with and without TMIVSB-1 for PP, were investigated by LOI, UL-94 test, thermogravimetric analyses (TGA) and Cone Calorimetry. TMIVSB-1 can obviously improve the flame retardant behavior of IFR systems according to the results of LOI values and UL-94 test. The results of LOI show that 2 wt% TMIVSB-1 can increase the LOI value by 3–5 unit compared with that of PP/IFR composite. The UL-94 test shows that PP with 20% IFR burns and has no rating, but the addition of a small content 2 wt% of TMIVSB-1 with 18 wt% of IFR can reach a UL-94 V-0 rating. TGA results show that the thermal stability of PP/IFR/TMIVSB-1 increases obviously more than that of PP/IFR when the temperature is above 265°C. From Cone Calorimetry results, it can be observed that the HRR peaks are not obviously decreased, but the burning time ...
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synergistic effect between a char forming agent cfa and microencapsulated ammonium polyphosphate on the thermal and flame retardant properties of polypropylene
Polymers for Advanced Technologies, 2008Co-Authors: Yuan Hu, Lei Song, Qingliang He, Dandan Yang, Hao ChenAbstract:The synergistic effect between a char forming agent (CFA) and microencapsulated ammonium polyphosphate (MAPP) on the thermal and flame retardancy of polypropylene (PP) are investigated by limiting oxygen index (LOI), UL-94 test, Cone Calorimetry, thermogravimetric analysis (TGA), scanning electron micrograph (SEM), and water resistance test. The results of Cone Calorimetry show that heat release rate peak (PHRR), total heat release (THR), and the mass loss of PP with 30 wt% intumescent flame retardant (IFR, CFA/MAPP = 1:2) decreases remarkably compared with that of pure PP. The HRR, THR, and mass loss decrease, respectively from 1140 to 100 kW/m2, from 96 to 16.8 MJ/m2, and from 100 to 40%. The PP composite with CFA/MAPP = 1:2 has the best water resistance, and it can still obtain a UL-94 V-0 rating after 168 hr soaking in water. Copyright © 2008 John Wiley & Sons, Ltd.
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Magnesium hydroxide sulfate hydrate whisker flame retardant polyethylene/montmorillonite nanocomposites
Journal of Materials Science, 2006Co-Authors: Hongdian Lu, Yuan Hu, Junfeng Xiao, Zhengzhou Wang, Zuyao ChenAbstract:Flame retardant maleated polyethylene/magnesium hydroxide sulfate hydrate whisker (MAPE/MHSH) composites containing organo-modified montmorillonite (OMT) were prepared by direct melt intercalation. Their morphology, combustion behaviour and thermal stability were carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), Cone Calorimetry and thermogravimetric analyses (TGA). The exfoliation of silicate layers within MAPE has been verified by XRD and TEM images. Cone Calorimetry results indicated that a synergistic flame retardant effect on reducing heat release rate (HRR) occurred when MHSH and OMT were both present in nanocomposite. The reduction in HRR improved as the mass fraction of OMT was increased from 2 to 10 wt%, but there was little improvement above 5 wt% OMT loading level. TGA profiles of the nanocomposites revealed that the thermodegradation stability of the nanocomposites decreased as the OMT fraction increased from 2 to 10 wt%.
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Influence of gamma irradiation on high density polyethylene/ethylene‐vinyl acetate/clay nanocomposites
Polymers for Advanced Technologies, 2004Co-Authors: Hongdian Lu, Yuan Hu, Qinghong Kong, Zuyao ChenAbstract:The study of high density polyethylene (HDPE)/ethylene-vinyl acetate (EVA)/and organically-modified montmorillonite (OMT) nanocomposites prepared by melt intercalation followed by exposure to gamma-rays have been carried out. The morphology and properties of the nanocomposites were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Cone Calorimetry. The purpose of the study focuses on the influence of gamma irradiation on the morphology, thermal stability and flammability properties of the nanocomposites. XRD studies and TEM images verified that the ordered intercalated nanomorphology of the nanocomposites was not disturbed by gamma irradiation. TGA data showed that the nano-dispersion of clay throughout the polymer inhibited the irradiation degradation of HDPE/EVA blend, which led to the nanocomposites exhibiting superior irradiation-resistant properties than that of the pure blend. Cone Calorimetry results indicated that the improvement in heat release rate (HRR) for irradiated HDPE/EVA blend was suppressed efficiently when clay was present. Increasing clay loading from 2 to 10% was beneficial by improving the flammability properties of the nanocomposites, but promoted a rapid increase in the sub-peak HRR at high irradiation dose level. Copyright © 2004 John Wiley & Sons, Ltd.