THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during ...     

Applications of micro-scale combustion calorimetry to the studies of cotton and nylon fabrics treated with organophosphorus flame retardants

Effective testing methods are critical for developing new flame retardant textiles by the industry. However, the current testing methods all have limitations. In this research, we applied micro-scale combustion calorimetry (MCC) for evaluating the flammability of the cotton woven fabric treated with a traditional reactive organophosphorus flame retardant in combination with a synergistic nitrogen-containing additive and the nylon-6,6 woven fabric treated with a hydroxyl-functional organophosphorus oligomer and crosslinkers. We found that MCC is capable of differentiating small differences among the treated fabric samples with similar flammability. MCC is able to make quantitative measurement of the peak heat release rate, the most important parameter related to fire hazard of materials, of textile whereas such analysis is more difficult using cone calorimetry due to textile fabrics’ low thickness. By using the thermal combustion parameters measured by MCC, we were able to calculate the limiting oxygen index (LOI) of various treated cotton fabric samples with near-perfect agreement between the experimentally measured and the predicted LOI values of treated cotton fabrics. We also compared the capability of MCC and differential scanning calorimetry for analyzing flame retardant cotton textiles.     

Effects of a semi‐bio‐based triazine derivative on intumescent flame‐retardant polypropylene

A semi‐bio‐based synergist (N, N′, N″‐1, 3, 5‐triazine‐2, 4, 6‐triyltris‐glycine [TTG]) was prepared by using glycine and cyanuric chloride. The structure of TTG was characterized by ¹H NMR and Fourier transform infrared spectroscopy. The TTG was applied in polypropylene (PP)/intumescent flame‐retardant compounds to improve its flame retardancy. The flame‐retardant properties of PP compounds were evaluated by limiting oxygen index and vertical burning tests (UL‐94). The results showed that 17 wt% intumescent flame‐retardant and 1 wt% TTG makes PP achieve the UL‐94 V‐0 rating without drippings, and the limiting oxygen index value is increased to 29.5 vol%. The thermal degradation behavior and char morphology of PP compounds were investigated by thermogravimetric analysis and scanning electron microscopy. The results indicated that TTG accelerates the formation of char layer, regulates the porous structure of char layer, and enhances its barrier property. Therefore, the temperatures of PP compound after two ignitions during the UL‐94 test are decreased significantly as shown in infrared thermal imaging. In addition, the combustion characteristics of PP compounds were investigated by cone calorimeter. The peak of heat release rate (PHRR) of PP compound is 67% reduced, and the t_PHRR is delayed from 223 to 430 seconds, indicates that the combustion risk of PP compound is reduced.     

Mechanical, thermal, and fire retardant properties of poly(ethylene terephthalate) fiber containing zinc phosphinate and organo-modified clay

The effect of zinc bisdiethylphosphinate (ZnPi) and organoclay on mechanical, thermal, and flame retardant properties of poly(ethylene terephthalate) (PET) fiber was investigated. ZnPi was preferred due to its fusible character at spinning temperature and organoclay was used for synergistic interaction. The mechanical, thermal, and flame retardant properties of fibers were examined by tensile testing, thermogravimetric analysis (TG), and micro combustion calorimeter (MCC). The tensile strength of the PET fiber reduced with the addition of both ZnPi and organoclay. The TG results showed that the inclusion of ZnPi increased the char residue. The MCC results showed that the addition of organoclay increased the barrier effect of formed char which depends on char amount, thickness, and integrity and reduces the maximum heat evolved during the test. This result was also important in terms of showing that the organoclay was effective in thermally thin samples.     

Thermal properties and combustion behaviors of flame retarded epoxy acrylate with a chitosan based flame retardant containing phosphorus and acrylate structure

Functional materials prepared from natural resources arouse a great interest recently. Herein, a novel natural material based flame retardant chitosan phosphate acrylate (GPCS) containing phosphorus and acrylate structure has been prepared. Its effect on thermal properties and combustion behaviors of epoxy acrylate (EA) has been investigated. Microscale combustion calorimeter (MCC) data showed that GPCS reduced the peak heat release (PHRR) and total heat release (THR) of samples greatly, which meant that GPCS was efficient in reducing the flammability of EA. The results of thermogravimetric analysis (TGA) exhibited that GPCS improved the thermal stability of materials at high temperature. Investigation of real time Fourier transform infrared (RT-IR) and thermogravimetric analysis/infrared spectrometry (TGA-IR) revealed that GPCS promoted the formation of char and reduced the release of combustible gas. Thermomechanical properties data showed that the storage modulus of samples increased then decreased with increasing GPCS content while the glass transition temperature continued reduced.     

超支化聚磷酸酯阻燃剂对尼龙6的成炭促进作用

以三氯氧磷和双酚A为原料制备了具有超支化结构的聚磷酸酯阻燃剂(HPPEA),通过红外(FTIR),核磁(1H-NMR,31P-NMR)及热重分析表征了产物的结构和热稳定性.将HPPEA与三聚氰胺聚磷酸盐(MPP)进行复配,通过熔融共混法制备阻燃尼龙6,通过氧指数法和垂直燃烧法测试了其阻燃性能,采用热重分析(TGA)研究...     

Microencapsulation of bisphenol-A bis (diphenyl phosphate) and influence of particle loading on thermal and fire properties of polypropylene and polyethylene terephtalate

Microencapsulated flame retardant, bisphenol-A bis (diphenyl phosphate) (BDP), with a silane shell was prepared by sol–gel process with the goal of incorporating them in polymeric matrices by melt blending to improve the flame retardancy of isotactic polypropylene (iPP) and polyethylene terephtalate (PET). The influence of the loading content on thermal transitions has been studied by differential scanning calorimetry (DSC), the thermal stability of the polymer/microcapsules composites has been assessed by thermogravimetric analysis (TGA) and cone calorimetry has been used to study the fire reaction. It was noticed that the microcapsules have a limited influence on the thermal transitions of iPP matrix, but a decrease of the melting and glass transition temperatures was detected for the PET microcomposites. TGA results showed that the addition of microcapsules could improve char formation of the PET systems both in nitrogen and in air atmospheres, whereas only a small improvement of the thermal stability was detected in oxidative atmosphere for the iPP samples. Furthermore, cone calorimeter experiments show that the incorporation of microcapsules in the iPP gives almost no improvement in the iPP fire reaction. However, the microcapsules act as flame retardant in PET reducing the heat release rate during the combustion and the total heat evolved. Therefore, microcapsules can act as a char promoter agent to enhance the fire resistance in the case of PET.     

Synthesis of a novel phosphorus‐containing curing agent and its effects on the flame retardancy,thermal degradation and moisture resistance of epoxy resins

A novel phosphorus‐containing compound diphenyl‐(1, 2‐dicarboxylethyl)‐phosphine oxide defined as DPDCEPO was synthesized and used as a flame retardant curing agent for epoxy resins (EP). The chemical structure of the prepared DPDCEPO was well characterized by Fourier transform infrared spectroscopy, and ¹H, ¹³C and ³¹P nuclear magnetic resonance. The DPDCEPO was mixed with curing agent of phthalic anhydride (PA) with various weight ratios into epoxy resins to prepare flame retardant EP thermosets. The flame retardant properties, combustion behavior and thermal analysis of the EP thermosets were respectively investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), cone calorimeter measurement, dynamic mechanical thermal analysis and thermogravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of the char residues for EP thermosets were respectively investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS). The water resistant properties of the cured EP were evaluated by putting the samples into distilled water at 70°C for 168 hr. The results revealed that the EP/20 wt% DPDCEPO/80 wt% PA thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.2%. The cone test results revealed that the incorporation of DPDCEPO effectively reduced the combustion parameters of the epoxy resin thermosets, such as heat release rate and total heat release. The dynamic mechanical thermal analysis test demonstrated that the glass transition temperature (Tg) decreased with the increase of DPDCEPO content. The TGA results indicated that the incorporation of DPDCEPO promoted the decomposition of epoxy resin matrix ahead of time and led to a higher char yield and thermal stability at high temperatures. The surface morphological structures and analysis of the XPS of the char residues of EP thermosets revealed that the introduction of DPDCEPO benefited the formation of a sufficient, compact and homogeneous char layer with rich flame retardant elements on the epoxy resin material surface during combustion. The mechanical properties and water resistance of the cured epoxy resins were also measured. After water resistance tests, the EP/20 wt% DPDCEPO/80 wt% PA thermosets retained excellent flame retardancy, and the moisture adsorption of the EP thermosets decreased with the increase of DPDCEPO content in EP thermosets because of the existence of the P–C bonds and the rigid aromatic hydrophobic structure in DPDCEPO. Copyright © 2015 John Wiley & Sons, Ltd.     

Synergistic effect of carbon nanotubes and decabromodiphenyl oxide/Sb2O3 in improving the flame retardancy of polystyrene

Brominated flame retardant polystyrene composites were prepared by melt blending polystyrene, decabromodiphenyl oxide, antimony oxide, multi-wall carbon nanotubes and montmorillonite clay. Synergy between carbon nanotubes and clay and the brominated fire retardant was studied by thermogravimetric analysis, microscale combustion calorimetry and cone calorimetry. Nanotubes are more efficient than clay in improving the flame retardancy of the materials and promoting carbonization in the polystyrene matrix. Comparison of the results from the microscale combustion calorimeter and the cone calorimeter indicate that the rate of change of the peak heat release rate reduction in the microscale combustion calorimeter was slower than that in the cone. Both heat release capacity and reduction in the peak heat release rate in the microscale combustion calorimeter are important for screening the flame retardant materials; they show good correlations with the cone parameters, peak heat release rate and total heat released.     

Organically modified montmorillonite as a synergist for intumescent flame retardant against the flammable polypropylene

Low flame retardant efficiency is a key bottleneck for currently available retardants against the flammable polypropylene (PP). Herein, the organically modified montmorillonite (OMMT) was utilized as a synergist for our previously reported intumescent flame retardant (IFR) that was constructed from ammonium polyphosphate (APP) and hyperbranched charring foaming agent (HCFA) to further enhance the retardant efficiency against PP. The resultant's combustion behavior was thoroughly investigated by cone calorimetry, limiting oxygen index (LOI), vertical burning test (UL‐94), and scanning electron microscopy (SEM). The results showed that 20% addition of IFR with OMMT showed a positive effect and improved the flame retardancy of the PP systems. Especially, addition of 2 wt% OMMT obviously increased the LOI values of PP systems with 20% total loading flame retardants from 29% to 31.5% and the samples meet V‐0 rating as well as the reduction of the heat release rate (HRR), total heat release (THR), CO₂, and CO production occurred. On the other hand, the SEM images were also revealed that OMMT initiated a dense and strong char on the surface of the material, which resulted in efficient flame retardancy of PP matrix during combustion. In addition, thermal degradation behavior discussed by thermogravimetric analysis (TGA) indicated that OMMT could improve the thermal stability of PP systems under high temperature, and promoted char residues of PP/IFR systems. Copyright © 2016 John Wiley & Sons, Ltd.     

Effect of chemical structure on combustion and thermal behaviour of polyurethane elastomer layered silicate nanocomposites

The effect of polyol molecular weight and functionality on nanodispersion of clay in PU/clay nanocomposites and the investigation of their thermal and combustion properties are reported and discussed. Lamellar elastomer polyurethane nanocomposites were synthesized using polyols with different molecular weight and functionality and according to these parameters they show several degrees of dispersion which affect their thermal and combustion behaviour. A barrier effect of clay layer is shown in TGA experiments by a delay of thermal degradation products release in nanocomposite materials compared to the virgin polymer; this barrier effect also leads to formation of char during combustion which lowers the peak of rate of heat release in cone calorimeter tests and eliminates fire-induced dripping of the nanocomposite sample during UL 94 test. However, in order to achieve non-burning behaviour nanocomposite technology must be combined with conventional flame retardant technology.     

Experimental study on the thermal behaviors of lithium-ion batteries under discharge and overcharge conditions

Iron oxide modified montmorillonite (MMT) as flame retardant was used to polyvinyl chloride (PVC), and the flame retardant and smoke-suppressant properties of the PVC were investigated by the smoke density rating and cone calorimeter tests (CONE), and the thermal degradation behaviors of PVC were studied by thermogravimetric analysis (TG) in air atmosphere. The activation energies for the first stage of thermal degradation were obtained following the equation of Kissinger. The mechanical properties testing resultant data showed that iron oxide modified MMT had little effect on the tensile strength of the sample. The CONE result indicated that iron oxide modified MMT could reduce the heat release rate in flame retardant PVC: a more compact char residue formed on the surface of the sample including iron oxide modified MMT during the combustion process. The TG result showed that the sample with modified iron oxide MMT had higher thermal stability than the pure PVC. Besides, the PVC treated with modified MMT showed high activation energy.     

Thermal analysis and EPR study of copper species in mordenites prepared by conventional and microwave-assisted methods

The main work of this thesis is to study and discuss flame-retardant properties of the flexible polyurethane foam (FPUF) added with borax, expanded graphite (EG), and EG/Borax as flame retardant, respectively. The thermal behavior of samples has been using thermogravimetry (TG) and differential thermogravimetry in air. The activation energies for different stages of thermal degradation are obtained following the equation of Kissinger. The flammability parameters, including limiting oxygen index, rate of heat release, total heat release, yield of CO, yield of CO₂, and smoke production rate, were recorded simultaneously. The char structure was studied by SEM, and their thermal stability and evolved gaseous products were examined by TG analysis–Fourier transform infrared spectroscopy. By analyzing these data, it was concluded that most combustion parameters of FPUF were decreased by the treatment, especially for EG/Borax treatment, which indicated a synergistic effect of flame retardancy. Meanwhile, the probable flame retardation mechanism was proposed.     

阻燃及可瓷化硅橡胶成炭结构的研究进展

简单介绍了硅橡胶的阻燃和瓷化机理。依据阻燃剂、填料及炭层结构的不同,将硅橡胶分为阻燃和可瓷化两大类.综述了阻燃硅橡胶和可瓷化硅橡胶的阻燃性能和成炭结构的研究进展。分析表明:添加物理或化学膨胀型阻燃剂的硅橡胶,燃烧过程中形成的炭层疏松多孔,阻燃隔热性能优异,但炭层强度差;添加非膨胀型阻燃剂的硅橡胶,炭层结构相对密实,但表面不平整,存在孔洞和裂缝,阻燃效果不好;添加可瓷化填料的硅橡胶燃烧形成的陶瓷炭层坚硬而致密,具有优异的耐火持久性,但在隔绝热量方面不如膨胀炭层。炭层的疏松隔热与坚固耐久兼顾是阻燃硅橡胶未来可能的发展方向。     

The synergistic flame‐retardant effect of O‐MMT on the intumescent flame‐retardant PP/CA/APP systems

The flame retardancy of a novel intumescent flame‐retardant polypropylene (IFR‐PP) system, which was composed of a charring agent (CA), ammonium polyphosphate (APP), and polypropylene (PP), could be enhanced significantly by adding a small amount (1.0 wt%) of an organic montmorillonite (O‐MMT). The synergistic flame‐retardant effect was studied systematically. The thermal stability and combustion behavior of the flame‐retarded PP were also investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL‐94), scanning electronic microscopy (SEM), and cone calorimeter test (CCT). TGA results demonstrated that the onset decomposition temperatures of IFR‐PP samples, with or without O‐MMT, were higher than that of neat PP. Compared with IFR‐PP, the LOI value of IFR‐PP containing 1.0 wt% O‐MMT was increased from 30.8 to 33.0, and the UL‐94 rating was also enhanced to V‐0 from V‐1 when the total loading of flame retardant was the same. The cone calorimeter results showed that the IFR‐PP with 1.0 wt% of O‐MMT had the lowest heat release rate (HRR), total heat release (THR), total smoke production (TSP), CO production (COP), CO₂ production (CO₂P), and mass loss (ML) of all the studied IFR‐PP samples, with or without O‐MMT. All these results indicated that O‐MMT had a significantly synergistic effect on the flame‐retardancy of IFR‐PP at a low content of O‐MMT. Copyright © 2009 John Wiley & Sons, Ltd.     

Synergistic effect of graphene oxide and boron-nitrogen structure on flame retardancy of natural rubber/IFR composites

In this paper, GO-BN(graphene oxide grafted boron nitride) was synthesized from graphene oxide and boron nitride by silane coupling agent KH550. Furthermore, GO-BN and intumescent flame retardant (IFR) were added into natural rubber (NR) simultaneously to improve its flame retardancy. The structure of GO-BN was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The analysis showed that GO-BN was successfully synthesized. The enhanced flame retardancy performance of flame retardant natural rubber (FRNR) was evaluated by limiting oxygen index (LOI) and UL-94 tests. Moreover, the combustion action of FRNR in fire was evaluated by cone calorimetry. Notably, the results showed that the sample with a GO-BN content of 12 phr showed the best flame retardancy performance. The heat release rate (HRR) and total heat release rate (THR) were remarkably decreased by 42.8% and 19.4%, respectively. Carbon residues were analyzed by infrared spectroscopy and scanning electron microscopy, which showed that GO-BN and IFR had a synergistic catalytic effect. The formation of compact thermal stable carbon layer after combustion was the key to protect engineering materials from combustion.     

Preparation of high-efficient flame retardant PA6 via DOPO-ITA initiated ring-opening polymerization of caprolactam

It has been a long-term challenge to synthesize intrinsically flame retardant polyamide 6 (FRPA6) with high-molecular weight. In this work, through the ring-opening polymerization of caprolactam initiated by 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10 phosphaphenanthrene-10-oxide (DOPO-ITA), intrinsically flame retardant PA6 with high-molecular weight was successfully prepared. Its chemical structure, thermal stability, mechanical and combustion properties, as well as the retarding mechanism were thoroughly characterized in detail. The FRPA6 containing 3.0% retardant could achieve a V-0 rating with an LOI value of 31.2%. An interesting phenomenon was observed during V-0 tests. The melt drip slowly extended downward to form a long strip after moving fire, which was in favor of its heat release in a short time, thereby effectively prevented it from igniting the cotton. That is, a facile method to prepare intrinsically high-efficiency fire retardant polymer via ring opening and polycondensation was proposed.     

Synergistic fire retardancy of colemanite, a natural hydrated calcium borate, in high-impact polystyrene containing brominated epoxy and antimony oxide

This study explores for the first time the synergistic fire retardant action of natural hydrated calcium borate, namely the mineral colemanite, which partially replaces antimony oxide in brominated flame retardant high-impact polystyrene compounds. Various antimony oxide to hydrated calcium borate ratios were employed keeping the brominated flame retardant additive at a constant loading level. With partial colemanite substitution for antimony oxide, lower heat release rate, total heat evolved and fire growth index was obtained under forced flaming fire conditions. Synergism was also seen in limiting oxygen index along with maintained V-0 classification in UL-94 tests. Regarding fire behaviour and flammability ratings, a large antimony oxide to calcium borate ratio provided ultimate fire retardant performance whereas magnitudes of synergism in average heat release rate and total heat evolved tend to be higher towards a smaller ratio. Effective heats of combustion and structural/morphological characterization of fire residues ascribed the underlying mechanism demonstrated by hydrated calcium borate to the formation of a consolidated residue that co-operates with the dominant gas phase fire retardancy originating from bromine-antimony synergism. It is thus proposed that coupling is achieved between gas phase and condensed phase modes of action increasing the overall fire retardant effectiveness. Along with enhanced fire retardancy, thermal stability and mechanical properties were satisfactorily maintained with the use of hydrated calcium borate at a variety of loading levels in compounds.     

Flame‐retardant poly (ethylene terephthalate) enabled by a novel melamine polyphosphate nanowire

A novel strategy was developed for the preparation of melamine polyphosphate (MPP) nanowires to achieve a superior flame‐retardant poly (ethylene terephthalate) (PET). Thanks to the well‐designed nanostructure, the prepared MPP nanowires exhibited great thermal stability and flame retardance. Herein with incorporation of only 1‐wt% MPP nanowires (PET/FR1.0 nanocomposite), the limiting oxygen index (LOI) value was dramatically increased to 29.4% from 20.5%, showing self‐extinguishing behavior. Moreover, PET/FR1.0 nanocomposite passed V‐0 UL‐94 rating in the vertical combustion test. However, PET containing 5‐wt% commercial MPP powder (PET/FR_C5.0) only showed a LOI of 27.9% and ignited the absorbent cotton with flammable melt‐droplets. Cone results also presented that introducing 1‐wt% MPP nanowires brought about a crucial decrease in fire hazard of PET, for instance, 11.1% and 7.7% maximum reduction in heat release rate and total heat release, respectively. Thermogravimetric analysis/infrared spectrometry (TG‐FTIR) result indicated that the main pyrolysis volatiles generated from PET degradation including benzoic acid, aromatic compounds, and carbon dioxide were apparently suppressed after introducing MPP nanowires into PET matrixes, suggesting the outstanding obstructing effect of graphited char residue formed in the combustion. This enhanced flame retardancy rooting in addition of MPP nanowires can be attributed to the combined dilution effect in gaseous phase and catalytic carbonization effect in condensed phase.     

Self-extinguishing polypropylene with a mass fraction of 9% intumescent additive II – Influence of highly oriented fibres

Recently, noticeably enhanced flame retardancy of multilayered self-reinforced composites, flame retarded with common ammonium polyphosphate based intumescent system, was described. In this paper the observed novel flame retardant synergism between intumescent additive system and highly oriented polymer fibres is further studied. The ignitability and combustion behaviour of flame retarded multilayer self-reinforced composites were compared to flame retardant compounds, prepared by simple melt compounding, of identical low additive contents, both when the heat was applied parallel (UL-94 tests) and perpendicular (cone calorimetric tests) with the direction of the embedded oriented tapes in self-reinforced composites. SEM and EDS analyses supported the different foaming process of the two types of samples to be understood, while the structure and character of the finally (after combustion) obtained charred layers were examined by compression tests. Considering the results of all the applied testing methods, the complex picture of the mechanism behind the enhanced flame retardant efficiency of flame retarded self-reinforced composites could be clarified.