Co-reporter:Xiu Liu, Khalifah A. Salmeia, Daniel Rentsch, Jianwei Hao, Sabyasachi Gaan
Journal of Analytical and Applied Pyrolysis 2017 Volume 124(Volume 124) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.jaap.2017.02.003
•A series of (DOPO) based derivatives were synthesized and incorporated as flame retardant additives in rigid polyurethane foam).•The synthesized DOPO derivatives exhibited excellent flame retardant properties, lowered the smoke and toxic gas production.•The synthesized DOPO derivatives work predominantly in the condensed phase.A series of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) based derivatives were synthesized and incorporated as flame retardant additives in rigid polyurethane foam (RPUF). The flame retardant performance of DOPO derivatives in RPUF was investigated and compared with traditional flame retardant tris(1-chloro-2-propyl) phosphate (TCPP) and reactive flame retardant (diol) based on oligomeric ethyl ethylene phosphate (PLF140). The flame retardant performance of rigid foams was evaluated by UL 94 HB test, limiting oxygen index (LOI) and cone calorimetry (CONE). Thermal stability of RPUF samples was analyzed by thermogravimetric analysis (TGA) and pyrolysis combustion flow calorimeter (PCFC). The thermal decomposition mechanism of the flame retardant RPUF and the mode of action of the flame retardants were investigated via pyrolysis-gas chromatography-mass spectrometry (Py-GC–MS) and thermogravimetric analyzer coupled with FTIR and MS (TG-FTIR-MS). Scanning electron microscope-energy dispersive X-ray (SEM-EDX) was used to analyze the char residue of the RPUF. It was observed that, addition of 2 wt% phosphorus in RPUF helps achieve HF1 rating in UL 94 HB test and reduces the peak of heat release rate by 23%–42% in cone calorimeter measurements. Additionally, in cone calorimeter measurements, compared to RPUF containing TCPP and PLF140, RPUF containing DOPO derivatives exhibit lower smoke and toxicant production and increased char residue. For RPUF containing 6-(2-(4,6-diamino-1,3,5-triazin-2-yl)ethyl) dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DTE-DOPO), production of decomposition products such as –NCO containing compounds, HCN, hydrocarbons, amines and cyanic acid were significantly decreased compared to virgin RPUF. RPUF/DTE-DOPO formulation resulted in a compact and tough char structure which proves its strong barrier effect in the condensed phase. The detailed flame retardant mechanisms of TCPP and DTE-DOPO in RPUF are further elaborated in this work.
Co-reporter:Yong Qiu;Zhen Liu;Lijun Qian
RSC Advances (2011-Present) 2017 vol. 7(Issue 81) pp:51290-51297
Publication Date(Web):2017/11/02
DOI:10.1039/C7RA11069C
A multi-phosphaphenanthrene compound (TDBA) was incorporated into polycarbonate (PC) to prepare a flame retardant composite. TDBA improved the flame retardancy of the PC material effectively. The PC composite comprising 10 wt% TDBA passed the UL94 V-0 level with a LOI value of 33.7%. The incorporation of TDBA effectively inhibited the combustion intensity of the TDBA/PC composite via reducing the production of flammable methane and carbonyl-containing substances, suppressing the oxidative process of combustible pyrolysis products, and promoting the PC matrix to form large-scale smoke particles. All these were caused by releasing phosphaphenanthrene fragments, PO, and phenoxyl free radicals from pyrolyzed TDBA. As an additive-type flame retardant with multiple phosphaphenanthrene groups, TDBA was verified to exert its effect mainly in the gaseous phase during flame retarding of PC materials.
Co-reporter:Xiaomei Yang;Yuanyuan Li;Yiliang Wang;Yunguo Yang
Journal of Polymer Research 2017 Volume 24( Issue 3) pp:
Publication Date(Web):2017 March
DOI:10.1007/s10965-017-1203-x
Novel nitrocellulose (NC)-based hybrid materials with self-synthesized heptaphenyltricycloheptasiloxane trihydroxy silanol (T7-POSS) as a modifier were prepared using a “one-step” chemical cross-linking process. To comprehensively demonstrate the superiority of the modifier, hybrid materials with different contents of T7-POSS were assessed. The gel content was measured, and the chemical structure and composition of the T7-POSS-NC hybrid materials were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) results showed that the thermal stability of the T7-POSS-NC hybrid materials increased with the T7-POSS content. Typically, when 12.3 wt.% T7-POSS was incorporated into the NC, the decomposition temperature based on 50% weight loss (T50%) was delayed from 183.3 °C to 243.5 °C, the maximum weight loss rate (WLRmax) decreased markedly from 432.9%/min to 1.3%/min, and the char residues increased from 1.4% to 26.0%. The scanning electron microscopy (SEM) results of the char residues indicated that the introduction of T7-POSS led to the formation of a sufficient and compact char layer. Notably, the incorporation of T7-POSS improved not only the combustion safety according to micro-scale combustion calorimeter (MCC) results but also the mechanical prop-erties due to the formation of cross-linking networks and the good distribution of T7-POSS particles, which was confirmed by SEM and energy-dispersive spectroscopy (EDS).
Co-reporter:Yong Qiu, Zhen Liu, Lijun Qian, Jianwei Hao
Journal of Analytical and Applied Pyrolysis 2017 Volume 127(Volume 127) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.jaap.2017.09.006
•Novel flame retardant TDBA with multiple DOPO groups was synthesized.•TDBA pyrolyzed along substituted DOPO and bisphenol-A routes.•TDBA exerted quenching and charring effects on burning epoxy thermosets.•TDBA endowed thermosets with excellent flame retardancy via bi-phase action.A novel flame retardant compound (TDBA) with multiple phosphaphenanthrene groups was synthesized and confirmed by chemical structural and elemental characterization. Contrastive analysis on thermal decomposition behavior showed that the two kinds of bridge bonds linking phosphaphenanthrene groups in TDBA caused a wider decomposition temperature range, contributing to inhibiting combustion in relatively longer time. The application of TDBA in epoxy thermosets suggested that, TDBA capacitated the limited oxygen index of thermosets to surpass 35% and 4 wt.% or more loadings of TDBA made 4,4′-diamino-diphenyl methane curing thermosets pass UL94 V-0 rating especially. During combustion, the incorporated TDBA induced the matrix to decompose earlier, reduced the fuels production, reduced burning intensity and inhibited the combustion reaction of fuels in gaseous phase, and promoted the charring behavior of thermosets in condensed phase. The pyrolysis of TDBA proceeded along two main directions, namely substituted phosphaphenanthrene and bisphenol-A. Through releasing massive phenolic derivatives, PO free radicals and other certain phosphorus-containing substances, TDBA is capable to exert free radical quenching effect in gaseous phase, and to promote charring behavior to form compact residue with barrier effect on heat and fuels transportation in condensed phase. This bi-phase joint action mode from TDBA endowed epoxy thermosets with excellent flame retardancy.
Co-reporter:Xiu Liu;Jing-Yu Wang;Xiao-Mei Yang
Journal of Thermal Analysis and Calorimetry 2017 Volume 130( Issue 3) pp:1817-1827
Publication Date(Web):10 July 2017
DOI:10.1007/s10973-017-6564-1
The aim of this work was to investigate the catalysis of boron phosphate (BP) on the thermal stability and char forming in flame-retardant polyurethane–polyisocyanurate foams (FPUR–PIR) with dimethylmethylphosphonate (DMMP) and tris(2-chloropropyl) phosphate (TCPP). The flame-retardant performance and thermal stability of FPUR–PIR were evaluated by cone calorimetry (CONE), thermogravimetric analysis (TG) and microscale combustion calorimetry (MCC). Gas-phase products of FPUR–PIR during the thermal decomposition were investigated via thermogravimetric analyzer coupled with FTIR and mass spectrometry (TG–FTIR–MS). Elemental composition and content of the charred layer in detail were analyzed by X-ray photoelectron spectroscopy (XPS). It was observed that the incorporation of 3 mass% BP in FPUR–PIR decreases the heat release rate, total smoke released and CO production. Meanwhile, the addition of 3 mass% BP advances the release of gaseous products and lower the production of smoke and toxic products like –NCO compounds, PO* and cyanic acid in the gas phase. It can accelerate the dehydration of hydroxyl compounds and promote the char formation of –NCO compounds. This can improve the thermal and oxidation resistance of condensed phase. The catalytic behavior of the dehydration and char formation of BP in the thermal degradation of FPUR–PIR is attributed to Brønsted and Lewis acidic sites on BP.
Co-reporter:Yiliang Wang, Xiaomei Yang, Hui Peng, Fang Wang, Xiu Liu, Yunguo Yang, and Jianwei Hao
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 15) pp:9925
Publication Date(Web):March 22, 2016
DOI:10.1021/acsami.6b00998
An efficient and multifunctional brucite/3-aminopropyltriethoxysilane (APTES)/nickel alginate/APTES (B/A/Nia/A) hybrid flame retardant was fabricated via the layer-by-layer assembly technique with brucite, silane coupling agents, nickel chloride, and sodium alginate. The morphology, chemical composition, and structure of the hybrid flame retardant were characterized. The results confirmed the multilayer structure and indicated that the assembled driving forces were electrostatic interactions, dehydration condensation, hydrogen bonds, and coordination bonds. When used in ethylene-vinyl acetate (EVA) resin, the multifunctional flame retardant had better performance than brucite in improving the flame retardancy, smoke suppression, and mechanical properties. With 130 phr loading, the multifunctional flame retardant achieved a limiting oxygen index value of 32.3% and a UL 94 V-0 rating, whereas the brucite achieved only 31.1% and a V-2 rating, respectively. The peak heat release rate and total heat released decreased by 41.5% and 8.9%, respectively. The multifunctional flame retardant had an excellent performance in reducing the smoke, CO, and CO2 production rates. These improvements could be attributed to the catalyzing carbonization of nickel compounds and the formation of more protective char layers. Moreover, the elongation at break increased by 97.5%, which benefited from the improved compatibility and the sacrificial bonds in the nickel alginate. The mechanism of flame retardant, smoke suppression, and toughening is proposed.Keywords: brucite; flame retardant; layer-by-layer assembly; nickel alginate; smoke suppression;
Co-reporter:Zhuang Miao, Jian-Gong Shi, Jian-Wei Hao, Qun-Bo Fan, Yi Zhang, Min-Hong Zhang
Ceramics International 2016 Volume 42(Issue 1) pp:1183-1190
Publication Date(Web):January 2016
DOI:10.1016/j.ceramint.2015.09.049
Controlling the morphology of α-Al2O3 plate-like powders is essential, asmulti-morphological α-Al2O3 platelets are needed in various applications. The α-Al2O3 platelets investigated in this work, were prepared via conventional solid-state reaction using gibbsite and pseudo-boehmite as the starting materials; nano-TiO2, nano-SiO2, silica gel, and the mixtures of nano-SiO2 and nano-TiO2 were used as morphology modifiers during the synthesis. The effect of the type and amount of modifiers used, on the morphology of the platelets was determined via scanning electron microscopy, X-ray diffraction, and measurements of the specific surface area. The results indicated that nano-TiO2 resulted in small and thick platelets. In fact, nano-TiO2 led to increased crystallinity and accelerated phase transformation to α-Al2O3, and additions of ≥2.00 wt% resulted in severe aggregation of the α-Al2O3 particles. Conversely, addition of nano-SiO2 led to significant increases in the diameter and reductions in the thickness of the α-Al2O3 platelets; for equal additions, liquid silica gel, which has excellent mobility, was more effective in controlling the morphology than solid SiO2. Additions of up to 1.00 wt% of the nano-SiO2 resulted in an incomplete α phase transformation, owing to SiO2 inhibition of the transformation to α-Al2O3. Moreover, simultaneous additions of nano-TiO2 and nano-SiO2 led to competing effects on the morphology of the α-Al2O3 particles, as evidenced by changes in the specific surface area.
Co-reporter:Xiu Liu, You Zhou, Hui Peng, Jianwei Hao
Polymer Degradation and Stability 2015 Volume 119() pp:242-250
Publication Date(Web):September 2015
DOI:10.1016/j.polymdegradstab.2015.05.020
The aim of this study was to investigate the acid catalysis of boron phosphate (BP) to model compound dipentaerythritol (DPER) which acted as char source during the thermal degradation and combustion. Various amounts of BP were added in DPER and then the thermal degradation and combustion behaviors were studied by means of thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). Evolved Gases were evaluated using TGA-FTIR; solid residues were fully characterized by FTIR, X-ray photoelectron spectroscopy (XPS), Raman analysis and scanning electron microscopy (SEM). The results of TGA and MCC showed that the addition of BP leaded to the earlier thermal degradation of DPER and increased the amount of char residues, significantly decreased the peak heat release rate of DPER; the results of TGA-FTIR, XPS, Raman analysis and SEM revealed that the presence of BP accelerated the dehydration of DPER, kept more carbon and oxygen elements in condensed phases, promoted the formation of compact and stable char layer. This study indicated that Lewis acidic and Brønsted acidic sites in BP altered the single degradation pathway and catalyzed the crosslinking and char forming of DPER. BP maybe as a potential acid source applied in intumescent flame retardant polymers in future.
Co-reporter:Hui Peng;Jie Feng;You Zhou;Zhuoshi Li;Hongfei Zou
Journal of Applied Polymer Science 2015 Volume 132( Issue 34) pp:
Publication Date(Web):
DOI:10.1002/app.42414
ABSTRACT
The effect of percolation and catalysis of bamboo-based active carbon (BAC) on the thermal degradation and flame retardancy of ethylene vinyl-acetate rubber (EVM) composites with intumescent flame retardants (IFR) consisting of ammonium polyphosphate (APP) and dipentaerythritol (DPER) has been investigated. The vulcanization characteristics were analyzed by a moving die rheometer. Thermogravimetric analysis (TGA) and fire behavior tests such as limiting oxygen index (LOI), vertical burning (UL 94), and cone calorimetry were used to evaluate the thermal properties and flame retardancy of EVM composites. Scanning electron microscopy (SEM) was used to study the morphology of residues of EVM composites. The addition of BAC significantly increased the maximum torque (MH) of EVM composites and EVM matrices. The combination of IFR with BAC can improve the thermal stability of EVM composites. Moreover, BAC can enhance char residue and promote the formation of a network for IFR. The current EVM/37IFR/3BAC composite achieved an LOI of 33.6% and a UL 94 V-0 rating. The PHRR, total heat release (THR), and total smoke release (TSR) for EVM/IFR/BAC were greatly reduced as compared to EVM/40IFR. Also, the mechanical properties of the EVMIFR/BAC composites increased with increasing BAC contents. The physical percolation effect between BAC and EVM before and after thermal degradation, and the chemical catalysis effect between BAC and IFR during thermal degradation are responsible for the improved flame retardancy of EVM composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42414.
Co-reporter:Xiu Liu;You Zhou;Jianxin Du
Journal of Applied Polymer Science 2015 Volume 132( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/app.41846
ABSTRACT
Three types of zinc salts, ZnAl2O4, ZnFe2O4, and Zn2SiO4, were prepared by coprecipitation. Potential smoke and toxicity suppression by zinc salts in flame-retardant polyurethane-polyisocyanurate foams (FPUR-PIR) with dimethylmethylphosphonate (DMMP) and tris (2-chloropropyl) phosphate (TCPP) were investigated. The crystal structure and dispersity of zinc salts in FPUR-PIR were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Smoke density, flame retardancy, and thermal degradation were studied using smoke density rating (SDR), limiting oxygen index (LOI), the cone calorimeter test, and thermogravimetry coupled with FTIR spectrophotometry (TGA-FTIR). The results indicated that pure zinc salts were obtained and evenly dispersed on the cell wall of FPUR-PIR. SDR and the specific extinction area (SEA) were significantly decreased, the time to second heat release rate peak (pk-HRR) of FRUP-PIR was delayed after incorporation of the zinc salts; zinc salts partially inhibited phosphorus oxide release into the gas phase, enhanced the condensed phase effect of phosphorus, reduced, and prolonged the release of isocyanate compound and hydrogen cyanide from FRUP-PIR; due to an increase in the amount of char residues, which indicated the suppression of smoke and toxicity volatiles. ZnFe2O4 resulted in better char formation at the initial degradation stage of FPUR-PIR, and ZnAl2O4 retained more phosphorus in the solid phase at higher temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41846.
Co-reporter:You Zhou, Jie Feng, Hui Peng, Hongqiang Qu, Jianwei Hao
Polymer Degradation and Stability 2014 110() pp: 395-404
Publication Date(Web):
DOI:10.1016/j.polymdegradstab.2014.10.009
Co-reporter:Mingming Si, Jie Feng, Jianwei Hao, Lishi Xu, Jianxin Du
Polymer Degradation and Stability 2014 100() pp: 70-78
Publication Date(Web):
DOI:10.1016/j.polymdegradstab.2013.12.023
Co-reporter:Jie Feng, Jianwei Hao, Jianxin Du, Rongjie Yang
Polymer Degradation and Stability 2012 Volume 97(Issue 1) pp:108-117
Publication Date(Web):January 2012
DOI:10.1016/j.polymdegradstab.2011.09.019
Polycarbonate was melt blended with solid bisphenol A bis(diphenyl phosphate), and a series of organoclays. Effects of the organoclay modifiers on the flammability, thermal and mechanical properties of the nanocomposites were studied by limiting oxygen index, UL-94 burning test, thermogravimetric analysis, differential scanning calorimetry, tensile test and dynamic mechanical analysis. Although all the nanocomposites exhibit an intercalated-exfoliated morphology, they vary in the magnitude of intercalation revealed by X-ray diffraction and transmission electron microscopy. Flammability of the nanocomposites is strongly related to the thermal stability rather than the morphology. Glass transition temperature (Tg) and mechanical properties are controlled by both the morphology and the affinity of the organoclays with the matrix. The modifier containing hydroxyl moiety has stronger interactions with the matrix but it can promote its degradation, thus the corresponding nanocomposite exhibits a better intercalated morphology, higher Tg, superior strength and modulus however a worse thermal stability and flame retardancy. An additional silane within the organoclays would make the organoclays more compatible with the matrix but be a steric obstacle to the intercalation of the matrix chains; however, flame retardancy of the corresponding nanocomposite is enhanced due to the flame retardant nature of the silane. Similarly, the modifier bearing two long alkyl tails shows stronger affinity with the matrix than the one bearing a single tail, but it would hinder the intercalation due to the steric effect. These establishments between organoclay modifiers and the properties of nanocomposites might be guidance for developing materials with practical applications.
Co-reporter:Weizhong Jiang, Jianwei Hao, Zhidong Han
Polymer Degradation and Stability 2012 Volume 97(Issue 4) pp:632-637
Publication Date(Web):April 2012
DOI:10.1016/j.polymdegradstab.2012.01.001
The thermal degradation behaviour of a novel caged bicyclic phosphate (Trimer) and its mixture with ammonium polyphosphate (APP) was studied by TG, FTIR and TG-FTIR. The flame retardant effect of Trimer/APP (IFR) in polypropylene (PP) was evaluated by limiting oxygen index (LOI) and vertical burning test (UL-94) at different mass ratio of Trimer and APP. Obvious synergistic effect can be observed between Trimer and APP, which remarkably improves the flame retardant properties of PP/IFR system. A maximum LOI value of 28.8% and UL-94 V-0 rating were achieved when the mass ratio of Trimer and APP was 2:1 at a total IFR loading of 25 wt%. Different degradation behaviour of Trimer/APP (with the mass ratio of 2:1) from APP or Trimer was observed by TG. The experimental TG curve of Trimer/APP, compared with the theoretically calculated one, showed lower initial degradation temperature and higher char residue at 800 °C, demonstrating interactions of Trimer and APP during thermal degradation. Such interactions were shown by gaseous degradation products analyzed by TG-FTIR. APP can chemically interact with Trimer, which changes the degradation process of Trimer. In the condensed phase, dehydration, cross-linking and char formation dominated the Trimer/APP interactions.
Co-reporter:Jie Feng, Jianwei Hao, Jianxin Du, Rongjie Yang
Polymer Degradation and Stability 2012 Volume 97(Issue 4) pp:605-614
Publication Date(Web):April 2012
DOI:10.1016/j.polymdegradstab.2012.01.011
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.
Co-reporter:Jie Feng, Jianwei Hao, Jianxin Du, Rongjie Yang
Polymer Degradation and Stability 2010 Volume 95(Issue 10) pp:2041-2048
Publication Date(Web):October 2010
DOI:10.1016/j.polymdegradstab.2010.07.005
A series of flame retardant formulations of solid bisphenol A bis(diphenyl phosphate) (S-BDP) and organo-montmorillonite (OMMT) were prepared based on polycarbonate (PC) by a melt compounding procedure. OMMT was well dispersed into the matrix showing an intercalated–exfoliated morphology. S-BDP and OMMT exhibit a synergistic effect in the vertical burning test (UL-94) but an antagonistic effect in the limiting oxygen index (LOI) evaluation. Thermogravimetric analysis (TGA) of the flame retarded PC system both under nitrogen and air was performed. Migration of S-BDP and OMMT towards the surface occurs during combustion. The introduction of OMMT could especially enhance the thermal-oxidative stability of the material, which is further confirmed by the analysis of the char residues by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS).
![2,6,7-Trioxa-1-phosphabicyclo[2.2.2]octane-4-methanol, 1,1',1''-phosphate, 1,1',1''-trioxide](/data/chemimg/1850700/56469-97-7.png)
![2,6,7-Trioxa-1-phosphabicyclo[2.2.2]octane-4-methanol, 1,1',1''-phosphate, 1,1',1''-trioxide](/data/chemimg/1850700/56469-97-7_b.png)
