Co-reporter:Aijuan Wang;Yuzhe Duan;Xiaoyu Gu
Chemical Research in Chinese Universities 2017 Volume 33( Issue 3) pp:492-498
Publication Date(Web):28 April 2017
DOI:10.1007/s40242-017-6388-3
Melt-dripping is always a big chanllenge in flame retardant finishing of synthetic fabrics. In this work, vinyltrimethoxysilane(VTMS) was introduced onto the polyamide66(PA66) surface by microwave grafting to improve the fire performance. The chemical structure of the grafted fabric was characterized by attenuated total reflection Fourier transformation infrared spectroscopy(ATR-FTIR) and X-ray photoelectron spectroscopy(XPS). The thermal stability analysis and flammability evaluation of the grafted samples by thermogravimetric analysis(TGA), cone calorimetry, vertical burning tests and limiting oxygen index(LOI) demonstrate that the presence of grafting chains significantly reduces the dripping tendency and decreases the heat release rate of polyamide66(PA66) fabric. The surface morphology observed by scanning electron microscope(SEM) indicates that VTMS can not only promote the formation of protective layers, which prevent the substrate from further thermal degradation, but also promote the char formation of PA66 substrate during combustion.
Co-reporter:Peng Jiang, Xiaoyu Gu, Sheng Zhang, Shende Wu, Qian Zhao, and Zhongwu Hu
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 11) pp:2974-2982
Publication Date(Web):March 2, 2015
DOI:10.1021/ie505021d
The novel phosphorus/nitrogen-containing flame retardant hexa(phosphaphenanthrene aminophenoxyl)cyclotriphosphazene (HPAPC), which contains phosphaphenanthrene [9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)] and phosphazene (hexachlorocyclotriphosphazene) groups, was synthesized by the classic Atherton–Todd reaction, and its chemical structure was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies. Poly(lactic acid) (PLA) composites containing HPAPC were prepared by melt blending, and their fire performance and thermal behaviors were investigated in terms of limiting oxygen index (LOI), vertical burning (UL-94), cone calorimeter tests, and thermogravimetric analysis (TGA). The LOI value could reach up to 34.7%, and UL-94 could pass V-0 for the PLA composite containing only 5 wt % HPAPC. TGA results showed that the char formation of PLA could be significantly improved by the presence of HPAPC. The evolved gas of the composite was analyzed by FTIR-TGA and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). The dispersion of fillers in PLA was observed by back-scattered electron (BSE). The char morphology was characterized by FTIR spectroscopy and scanning electronic microscopy (SEM). It was suggested that the presence of HPAPC could release ammonia gas during combustion, which was beneficial to the formation of an intumescent char structure.
Co-reporter:Peng Jiang, Qian Zhao, Sheng Zhang, Xiaoyu Gu, Zhongwu Hu, and Guozhi Xu
Industrial & Engineering Chemistry Research 2015 Volume 54(Issue 23) pp:6085-6092
Publication Date(Web):May 26, 2015
DOI:10.1021/acs.iecr.5b01104
Chemical grafting and pad-dry physical treatment with maleic anhydride (MA) and 2-hydroxyethyl methacrylate (HEMA) were employed to improve the fire resistance of polyamide 66 (PA 66) fabric, respectively. The flammability characterization demonstrated that chemical grafting could improve the antidripping property of the fabric by the elimination of the melting process which resulted from the so-called “scaffolding effect” during combustion. Pad-dry physical treatment improved the fire performance (including antidripping tendency) of PA 66 fabric through notable molten contraction which could keep the fabric away from the igniting source. It has been suggested that the premature decomposition of the monomers/graft chains can remove the heat from the fiber and delay the further decomposition of the substrate. The chemical grafting significantly improved the hydrophilicity of the samples, while the physical treatment decreased the hydrophilicity of PA 66 samples.
Co-reporter:Hongfei Li, Zhongwu Hu, Sheng Zhang, Xiaoyu Gu, Huajin Wang, Peng Jiang, Qian Zhao
Progress in Organic Coatings 2015 Volume 78() pp:318-324
Publication Date(Web):January 2015
DOI:10.1016/j.porgcoat.2014.08.003
•The introduction of TiO2 can improve the fire-resistance of coating.•The melt flow rate (MFR) is closely related to the formation of intumescent char.•Anatase-type TiO2 transfers into rutile-type TiO2 at high temperature.Rutile-type TiO2 (r-TiO2) or anatase-type TiO2 (a-TiO2) in association with a conventional intumescent flame retardant system which contains ammonium polyphosphate/pentaerythritol/melamine (APP–PER–MEL) was introduced to silicone-acrylate coatings to improve the fire resistance. The effect of TiO2 on the fire-resistance and thermal properties of APP–PER–MEL coating has been investigated by using big panel method and thermogravimetry (TG). The limit of fire-resistance of the sample containing 30 phr rutile-type TiO2 (73 min) is much longer than that of the sample containing 30 phr anatase-type TiO2 (34 min). The morphology and structure of charring layers were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The relationship between charring process and melt flow rate (MFR) of silicone-acrylate was also discussed. It is suggested that MFR value can significantly affect the formation of char, and a moderate silicone-acrylate MFR is required to form good quality char.
Co-reporter:Huan Zou;Jun Sun;Xiao-yu Gu;Peng Jiang
Chinese Journal of Polymer Science 2015 Volume 33( Issue 4) pp:554-563
Publication Date(Web):2015 April
DOI:10.1007/s10118-015-1606-2
Nano-SiO2 and/or MoO3 were introduced to ethylene-vinyl acetate/nitrile butadiene rubber (EVA/NBR) blends containing magnesium hydroxide (MH) and red phosphorus (RP) to further improve the mechanical properties, oil resistance, smoke suppression and flame retardancy. The results indicated that the tensile strength and oil resistance were significantly improved by incorporating nano-SiO2. Smoke suppression tests for EVA/NBR blend samples showed that both nano-SiO2 and MoO3 can significantly reduce smoke release amount. The flammability characterization indicated that the blended sample with an LOI value of 33.0 could achieve V-0 level in the UL-94 test. Cone calorimetry test data showed the peak heat release rate was 67% lower than that for pure EVA/NBR. Thermal analysis showed that the presence of both nano-SiO2 and MoO3 was beneficial to promoting char formation of the EVA/NBR blends. Char residual analysis suggested that MoO3 aggregated in solid phase during combustion.
Co-reporter:Peng Jiang, Xiaoyu Gu, Sheng Zhang, Jun Sun, Riwei Xu, Serge Bourbigot, Sophie Duquesne, Mathilde Casetta
Polymer 2015 Volume 79() pp:221-231
Publication Date(Web):19 November 2015
DOI:10.1016/j.polymer.2015.10.029
•A novel phosphorus/nitrogen contained flame retardant HPHAPC was synthesized.•The fire performance of PLA/PC was synergistically improved by HPHAPC and POSS.•The flame retardant mechanism of HPHAPC/POSS in PLA/PC was proposed and discussed.This work reports our recent efforts on improving the flame retardancy and thermal stability of biodegradable poly (lactic acid) (PLA) which is usually produced from corn and sugar beets. Hexa-(phosphaphenanthrene-methyl-(p-hydrobenzal)-amino-phenoxyl)-cyclotriphosphazene (HPHAPC) was synthesized by the classic Kabachnik-Fields reaction, and was then incorporated into PLA/polycarbonate (PC) alloys by melt blending. The flammability evaluation by limiting oxygen index (LOI), vertically burning (UL-94) and cone calorimeter tests has indicated that the LOI value can reach up to 31.5 and UL-94 grade can pass V-0 by the presence of only 3 wt% HPHAPC and 3 wt% polyhedral oligomeric silsesquioxane (POSS). The thermal behavior characterization by thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) shows that the char formation of PLA/PC alloys can be significantly enhanced by the presence of HPHAPC/POSS. The evolved gas of the alloys was analyzed by Fourier transform infrared spectroscopy-TGA (FTIR-TGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Char morphology was observed by scanning electronic microscopy (SEM). It is demonstrated that HPHAPC can react with POSS during processing to form an intumescent char structure. It is proposed that the degradation products of HPHAPC/POSS can capture free radicals in the gas phase and enhance char formation in the condensed phase.
Co-reporter:Mingzhe Dong, Xiaoyu Gu, and Sheng Zhang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 19) pp:8062
Publication Date(Web):April 15, 2014
DOI:10.1021/ie500178u
Compound oxides (NiFeO and CoFeO) were obtained by calcining layered double hydroxide (LDH) precursors prepared by microwave-hydrothermal method. The structure of LDHs and compound oxides was characterized by X-ray diffraction (XRD). The thermal behavior and flammability of polypropylene (PP) composites containing different types of compound oxides were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimeter. Fire performance characterization has demonstrated that both NiFeO and CoFeO can significantly increase the LOI of PP/IFR. NiFeO and CoFeO can improve the char quality of PP/intumescent flame retardant (IFR) composite and the thermal stability of formed char. The heat release rate (HRR) of a PP/IFR sample containing 2 wt % CoFeO could be decreased by 33%, compared with that of PP/IFR sample. The char residue of PP composites after cone test was characterized by laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS). It is suggested that compound oxides containing transition metals can enhance the flame retardancy of a PP composite through trapping free radicals in the gas phase and improving the char quality in the condensed phase.
Co-reporter:Jun Sun;Xiaoyu Gu;Mathieu Coquelle;Serge Bourbigot;Sophie Duquesne;Mathilde Casetta
Polymers for Advanced Technologies 2014 Volume 25( Issue 10) pp:1099-1107
Publication Date(Web):
DOI:10.1002/pat.3358
A nitrogen-, phosphorus- and chlorine-containing flame retardant, hexachlorocyclotriphosphazene (HCTP), has been covalently grafted onto the surface of multi-wall carbon nanotubes (MWNT) to obtain MWNT-HCTP. Polyamide 6 (PA6)/MWNT composites were then prepared via melt compounding. The flammability of PA6/MWNT composite was characterized by cone calorimetry, limiting oxygen index (LOI) and UL-94 tests. The results showed that peak heat release rate of samples containing 3 wt% MWNT-HCTP was only 460 kW/m2, which decreased by 35.2% compared with that of a neat PA6 sample. The LOI value was increased from 22.7% to 26.5%, and UL-94 test performance was also significantly improved by the presence of MWNT-HCTP. Scanning electron microscope (SEM) and optical microscope analysis showed that modified MWNT had a better dispersion and compatibility in PA6 than unmodified MWNT. The composition of residue chars and volatile products was investigated by SEM/energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric-FTIR, respectively. It was proposed that grafted HCTP was mainly functioned in the condensed phase, where P, N can synergistically promote char formation and Cl element can catch free radicals to terminate the chain reaction during combustion of the PA6 composite. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Jun Sun;Xiaoyu Gu;Mathieu Coquelle;Serge Bourbigot;Sophie Duquesne;Mathilde Casetta
Polymers for Advanced Technologies 2014 Volume 25( Issue 12) pp:1552-1559
Publication Date(Web):
DOI:10.1002/pat.3400
Melamine polyphosphate (MPP) and halloysite nanotubes (HNT) were introduced to polyamide 6 (PA6) by melt blending in order to improve the fire resistance. PA6 composite containing 12% flame retardants with good spinnability was obtained. The flammability of PA6 composite was characterized by limiting oxygen index (LOI), UL-94 vertical burning and cone calorimeter (CONE) tests. The results indicated that the LOI value could reach 24.0 vol.% and UL-94 rating could achieve V2 level at the presence of 12% flame retardants. CONE data demonstrated that peak heat release rate was significantly reduced from 554 kW/m2 of neat PA6 to 368 kW/m2 of the sample containing flame retardants. Thermal analysis indicated that the thermal stability and char formation were improved by the presence of flame retardants. The morphology of residue char was characterized by scanning electron microscopy; and it suggested that a network-structured protective char layer had been formed. The possible synergism between MPP/HNT and their flame retardant mechanism was also analyzed and discussed. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Qian Zhao, Xiaoyu Gu, Sheng Zhang, Mingzhe Dong, Peng Jiang, Zhongwu Hu
Surface and Coatings Technology 2014 240() pp: 197-203
Publication Date(Web):
DOI:10.1016/j.surfcoat.2013.12.003
Co-reporter:Mingzhe Dong, Xiaoyu Gu, Sheng Zhang, Hongfei Li, and Peng Jiang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 26) pp:9145
Publication Date(Web):June 7, 2013
DOI:10.1021/ie4011222
A Lewis acid has been considered as a char promoter during the combustion of polymers. The acidified 4A zeolites (HA zeolite) containing Lewis acid sites (4A-L zeolite) and Brønsted-acid sites (4A-H+ zeolite) were prepared and their crystallinity and acidic site structure were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The thermal behavior and flammability of a polystyrene (PS) composite containing different types of zeolite were investigated by thermogravimetric analysis (TGA), volatile gas and condensed phase FTIR analysis, limiting oxygen index (LOI), and cone calorimeter. Both 4A-L and 4A-H+ zeolite could enhance the flame retardancy of a PS composite significantly. The heat release rate (HRR) of a PS composite could be decreased by 48% after adding 2% 4A-L. It is suggested that Lewis acidic sites in HA zeolite can alter the degradation route and enhance the char formation of a PS composite.
Co-reporter:Xueyan Li, Xiaoyu Gu, Sheng Zhang, Hongfei Li, Qingli Feng, Jun Sun, and Qian Zhao
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 6) pp:2290-2296
Publication Date(Web):January 3, 2013
DOI:10.1021/ie302452e
Our previous study has demonstrated that photografting can enhance the flame retardancy of both polyamide and polyester fabric. In this work, efforts to use chemical grafting with acrylamide (AM) as the monomer and dibenzoyl peroxide (BPO) as the initiator were made to improve the homogeneity of the grafting chains and the flame retardancy of nylon 6,6 fabric. The effects of reaction time, reaction temperature, and monomer concentration on the percentage of grafting (PG) were investigated. The effect of PG on the fire performance of AM-g-nylon 6,6 fabric was also studied. The flame retardancy and thermal behavior were characterized in terms of the limiting oxygen index (LOI), UL 94 test, cone calorimetry, thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The results showed that the after-flame time and char length were significantly reduced after grafting. The heat release rate (HRR) of grafted sample was decreased by 28% compared to that of the ungrafted sample. The optimal grafting conditions were obtained as follows: reaction time, 1.5 h; reaction temperature, 70 °C; and concentration of total monomer, 15 wt %. The chemical structure and microstructure of AM-g-nylon 6,6 fabric were analyzed by attenuated-total-reflection Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM), respectively. A possible grafting mechanism is proposed and discussed.
Co-reporter:Xinjuan Zhang, Xipeng Pu, Yu Chen, Xiaoyu Gu, Di Xu, Sheng Zhang
Materials Letters 2013 Volume 112() pp:129-132
Publication Date(Web):1 December 2013
DOI:10.1016/j.matlet.2013.08.096
•High concentration Ga-doped ZnO nano-powders were successfully prepared through the sol–gel combustion method.•The smallest ZnO crystallite size was reduced to around 5.7 nm at the presence of 20 mol% Ga.•The band gap of Ga-doped ZnO increases with the concentration of Ga.•Ga-doped ZnO shows enhanced absorption capacities and improved photocatalytic activities.High concentration (up to 20 mol%) Ga-doped ZnO (GZO) nano-powders were prepared by a sol–gel combustion method. The crystal structure, morphology, and crystallite size of GZO were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that Ga3+ ions had been successfully doped into ZnO, and all GZO samples were of a single phase and had the same wurtzite structure as pure ZnO. Moreover, the crystal growth rate of ZnO was suppressed by the presence of Ga, and the crystallite size of ZnO can be reduced to around 5.7 nm at the presence of 20 mol% Ga. The absorption spectra showed that the optical band gap energy (Eg) of GZO nano-powder was in the range of 3.013–3.219 eV. The reflectance spectra showed that all the samples had very high reflectivity in the wavelength region between 450 and 2500 nm, which indicated the potential use in cooling materials. The photocatalytic activities of ZnO and GZO nano-powders were evaluated using methyl orange degradation in aqueous solution under sunlight and UV light irradiation. The results showed that the photocatalytic activities and the adsorption capacities increase with Ga content.
Co-reporter:Qingli Feng, Xiaoyu Gu, Sheng Zhang, Bin Zhao, Jun Sun, Xueyan Li, and Mingzhe Dong
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 45) pp:14708
Publication Date(Web):October 23, 2012
DOI:10.1021/ie301508q
A flame retardant system containing 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP) and ammonium sulfamate (AMS) was proven to be effective on improving the fire performance of polyethylene terephthalate (PET) fabric. The flammability tests indicate that this FR system can impart dripping resistance to PET fabric and the limiting oxygen index value can reach up to 28. The thermal behavior of PET fabric was investigated by thermo-gravimetric analysis. The results indicate that the residual char of treated samples was significantly improved by the presence of HEDP and AMS. The morphology of treated PET fabric residue was also characterized by scanning electron microscope analysis. It has been suggested that intumescent char structures have been formed.
Co-reporter:Sheng Zhang, T. Richard Hull, A. Richard Horrocks, Gill Smart, Baljinder K. Kandola, John Ebdon, Paul Joseph, Barry Hunt
Polymer Degradation and Stability 2007 Volume 92(Issue 4) pp:727-732
Publication Date(Web):April 2007
DOI:10.1016/j.polymdegradstab.2006.12.001
Flammability of synthetic fibres is significantly worse than that of bulk polymers because of the high surface area to volume ratio and the low tolerance to high filler loadings in the fibre production process. Introducing nanocomposite structures has the potential to enhance the char formation at relatively low loadings of nanoparticulate fillers and hence can reduce the flammability of synthetic polymers and fibres.This paper reports thermal degradation analysis results in conjunction with TG analysis under different atmospheres and further studies of X-ray diffraction characterisation of fibre-forming polypropylene containing selected dispersed nanoclays.The concentrations of hydrocarbons, carbon monoxide and carbon dioxide released during the TG analysis have been monitored and analysed by using a combined electrochemical infrared analyser. The intensity changes of the crystallinity peaks and nanoclay peaks in the polymer and composites are discussed.
![Methanol, 1-[(4,6-diamino-1,3,5-triazin-2-yl)amino]-](/data/chemimg/3756500/937-35-9.png)
![Methanol, 1-[(4,6-diamino-1,3,5-triazin-2-yl)amino]-](/data/chemimg/3756500/937-35-9_b.png)
