Synergistic effects of β‐cyclodextrin containing silicone oligomer on intumescent flame retardant polypropylene system

The effects of β‐cyclodextrin containing silicone oligomer(CDS), as a synergistic agent, on the flame retardancy and mechanical properties of intumescent flame retardant polypropylene composites were studied by adding different amounts of CDS in intumescent flame retardants. The limiting oxygen index (LOI), UL‐94 test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were utilized to evaluate the synergistic effects of CDS in the composites. It was found that after a little amount of CDS partially replaced a charring‐foaming agent (CFA) in IFR, LOI values of the composites were enhanced and they obtained a UL‐94 V‐0 rating. IFR system containing 6.25wt% CDS presented the best flame retardancy in PP. The experimental results obtained from LOI and UL‐94, TGA, SEM, and mechanical properties indicated that the combination of CDS and CFA presents synergistic effects in flame retardancy, char formation, and mechanical properties of the composites. This is probably due to different structures of polyhydroxyl macromolecules (CDS and CFA), the existence of dimethyl silicone group in CDS, and the toughness of epoxy silicon chain in CDS. SEM results proved that the interfacial compatibility between IFR and PP was improved by CDS. Copyright © 2009 John Wiley & Sons, Ltd.     

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.     

聚苯氧基磷酸联苯二酚酯/聚磷酸铵膨胀阻燃剂对环氧树脂阻燃性能影响研究

以聚苯氧基磷酸联苯二酚酯(PBPP)与聚磷酸铵(APP)组成复合阻燃剂,对环氧树脂(EP)进行阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法研究改性环氧树脂的阻燃性能和阻燃机理.结果表明,PBPP/APP体系对EP具有较好的阻燃性能,阻燃剂添加量为10%时能使环氧树脂的氧指数提高到29.6%,垂直燃烧等级达到UL94 V-0级,残炭量大大增加;平均热释放速率下降45.7%,热释放速率峰值下降51.0%,有效燃烧热平均值下降21.1%;TGA、CONE、SEM等综合分析显示了PBPP/APP改性后的环氧树脂比纯环氧树脂具有更高的热稳定性,燃烧后能够形成连续、致密、封闭、坚硬的焦化炭层,在聚合物表面产生有效覆盖、隔绝了氧气,改善了环氧树脂的燃烧性能.     

Enhancement of a hyperbranched charring and foaming agent on flame retardancy of polyamide 6

A hyperbranched polyamine was prepared using an A₂ + B₃ approach. It acted as a hyperbranched charring and foaming agent (HCFA) in combination with ammonium polyphosphate (APP) to form a new intumescent flame retardant (IFR) system for polyamide 6 (PA6). Effect of HCFA on flame retardant and thermal degradation properties of IFR‐PA6 was investigated by limiting oxygen index (LOI), UL‐94 vertical burning, cone calorimeter, and thermogravimetric analysis (TGA) tests. The IFR system presented the most effective flame retardancy in PA6 when the weight ratio of APP to HCFA was 2:1. The LOI value of IFR‐PA6 could reach 36.5 with V‐0 rating when the IFR loading was 30 wt%. Even if the loading decreased to 25 wt%, IFR‐PA6 could still maintain V‐0 rating with an LOI value of 31. TGA curves indicated that APP would interact with both PA6 and HCFA in PA6/APP/HCFA composite under heating. The interaction between APP and HCFA improved the char formation ability of IFR system and then much more char was formed for PA6/APP/HCFA composite than for PA6/APP. Therefore, better flame retardancy was achieved. Moreover, the structure and morphology of char residue were studied by Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results indicated that compact and foaming char layer containing P‐O‐C structure was formed for PA6/APP/HCFA system during combustion. Copyright © 2010 John Wiley & Sons, Ltd.     

Effect of a novel charring-foaming agent on flame retardancy and thermal degradation of intumescent flame retardant polypropylene

A new triazine polymer was synthesized by using cyanuric chloride, ethanolamine and ethylenediamine as raw materials. It is used both as a charring agent and as a foaming agent in intumescent flame retardants, designated as charring-foaming agent (CFA). Effect of CFA on flame retardancy, thermal degradation and mechanical properties of intumescent flame retardant polypropylene (PP) system (IFR-PP system) has been investigated. The results demonstrated that the intumescent flame retardant (IFR) consisting of CFA, APP and Zeolite 4A is very effective in flame retardancy of PP. It was found that when the weight ratio of CFA to APP is 1:2, that is, the components of the IFR are 64 wt% APP, 32 wt% CFA and 4 wt% Zeolite 4A, the IFR presents the most effective flame retardancy in PP systems. LOI value of IFR-PP reaches 37.0, when the IFR loading is 25 wt% in PP. It was also found that when the IFR loading is only 18 wt% in PP, the flame retardancy of IFR-PP can still pass V-0 rating, and its LOI value reaches 30.2. TGA data obtained in pure nitrogen demonstrated that CFA has a good ability of char formation itself, and CFA shows a high initial temperature of the thermal degradation. The char residue of CFA can reach 35.7 wt% at 700 °C. APP could effectively promote the char formation of the APP-CFA system. The char residue reaches 39.7 wt% at 700 °C, while it is 19.5% based on calculation. The IFR can change the thermal degradation behaviour of PP, enhance T_max of the decomposition peak of PP, and promote PP to form char, based upon the results of the calculation and the experiment. This is attributed to the fact that endothermic reactions took place in IFR charring process and the char layer formed by IFR prevented heat from transferring into inside of IFR-PP system. TGA results further explained the effective flame retardancy of the IFR containing CFA.     

Synthesis of bio‐based poly (cyclotriphosphazene‐resveratrol) microspheres acting as both flame retardant and reinforcing agent to epoxy resin

A highly cross‐linked poly (cyclotriphosphazene‐resveratrol) microsphere (PRV) was synthesized by using hexachlorocyclotriphosphazene (HCCP) and bio‐based resveratrol (REV) as raw materials, and the obtained PRV microspheres were applied to improve the flame retardancy and mechanical property of epoxy resin (EP). The TGA results showed that the PRV microsphere is an excellent charring agent and the char yield is as high as 62% at 800°C. The incorporation of PRV makes the initial degradation earlier yet significantly increases the char residue of EP composites. Moreover, the introduction of PRV microspheres into EP greatly promoted the flame retardancy performance. Under 3% of addition of PRV microspheres, the peak heat release rate (PHRR) and total heat release (THR) were decreased by 58.3% and 29.6%, respectively, the limited oxygen index (LOI) value was increased to 29.7% from 25.3% of pure EP. In addition, because of the uniform distribution in EP matrix and the enhancing effect of PRV microspheres, the mechanical properties including tensile modulus of EP composites were strengthened. PRV microspheres in this paper provide a possibility to synthesize a dual functional filler, which acts as both flame retardant and strengthening agent.     

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.     

An efficiently halogen-free flame-retardant long-glass-fiber-reinforced polypropylene system

In order to solve the “candlewick effect” caused by glass fibers, which results in the decrease of flame retardancy of flame-retardant long-glass-fiber-reinforced polypropylene (LGFPP) systems, and the deterioration of mechanical properties caused by adding an additional amount of flame retardants compared with flame-retardant non-glass-fiber-reinforced polypropylene systems so as to keep a same flame retardancy, a novel intumescent flame retardant (IFR) system, which is composed of a charring agent (CA), ammonium polyphosphate (APP) and organically-modified montmorillonite (OMMT), was used to flame retard LGFPP. The thermal stability, combustion behavior, char formation, flame retardant mechanism and mechanical properties of the IFR-LGFPP samples were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 test, cone calorimeter test, scanning electronic microscopy, and mechanical property tests. When the content of IFR is 20 wt%, the LOI value of IFR-LGFPP reaches 31.3, and the vertical burning test reaches UL-94 V-0 rating, solving the “candlewick effect” caused by long glass fiber without additional amount of the IFR. All the relevant cone calorimeter parameters also show that IFR-LGFPP has much better flame-retardant behaviors than LGFPP. Furthermore, the mechanical properties of IFR-LGFPP almost remain unchanged in comparison with those of LGFPP containing no IFR. The flame retardant mechanism was also discussed.     

Effect of a novel charring agent on thermal degradation and flame retardancy of acrylonitrile–butadiene–styrene

A novel charring agent poly(p-propane terephthalamide) (PPTA) was synthesized by using terephthaloyl chloride and 1,3-propanediamine through solution polycondensation and it was used together with ammonium polyphosphate (APP) to prepare a novel intumescent flame retardant (IFR) for ABS. The thermal degradation behaviour and flame retardancy were investigated, the results showed that PPTA could be effective as a charring agent, the flame retardancy of ABS and the mass of residues improved greatly with the addition of IFR. When the content of APP was 22.5 mass% and PPTA was 7.5 mass%, the limiting oxygen index (LOI) value of IFR-ABS system was found to be 32.4, and class V-0 of UL-94 test was passed. Moreover, the synergistic effects of two different adjuvants AlPi and MnO₂ in IFR-ABS system have been studied.     

Flame retardant and toughening behaviors of bio‐based DOPO‐containing curing agent in epoxy thermoset

Based on bio‐based furfural, a phosphorus‐containing curing agent (FPD) was successfully synthesized, via the addition reaction between 9,10‐dihydro‐9‐oxa‐10 phosphaphenanthrene‐10‐oxide (DOPO) and furfural‐derived Schiff base. Then, as co‐curing agent, FPD was used to prepare flame retardant epoxy thermosets (EP) cured by 4, 4′‐diaminodiphenyl methane. The incorporated FPD improved the flame retardancy and toughness of epoxy thermoset, simultaneously. When 5 wt% FPD was added into EP, the FPD/EP achieved 35.7% limited oxygen index (LOI) value and passed UL94 V‐0 rating, meanwhile. In FPD/EP thermoset, the incorporated FPD reduced the thermal decomposition rate, increased the charring capacity, and inhibited the combustion intensity of epoxy thermoset. Through gas‐phase and condensed‐phase actions in weakening fuel supply, suppressing volatile combustion, and enhancing charring barrier effect, FPD decreased the heat release of burning epoxy thermoset, significantly. For the outstanding effectiveness on both flame retardancy and toughness, the study on FPD provides a promising way to manufacture high‐performance epoxy thermoset.     

Flame‐retardant performance and mechanism of epoxy thermosets modified with a novel reactive flame retardant containing phosphorus,nitrogen, and sulfur

A novel phosphorus‐containing, nitrogen‐containing, and sulfur‐containing reactive flame retardant (BPD) was successfully synthesized by 1‐pot reaction. The intrinsic flame‐retardant epoxy resins were prepared by blending different content of BPD with diglycidyl ether of bisphenol‐A (DGEBA). Thermal stability, flame‐retardant properties, and combustion behaviors of EP/BPD thermosets were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limited oxygen index (LOI) measurement, UL94 vertical burning test, and cone calorimeter test. The flame‐retardant mechanism of BPD was studied by TGA/infrared spectrometry (TGA‐FTIR), pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), morphology, and chemical component analysis of the char residues. The results demonstrated that EP/BPD thermosets not only exhibited outstanding flame retardancy but also kept high glass transition temperature. EP/BPD‐1.0 thermoset achieved LOI value of 39.1% and UL94 V‐0 rating. In comparison to pure epoxy thermoset, the average of heat release rate (av‐HRR), total heat release (THR), and total smoke release (TSR) of EP/BPD‐1.0 thermoset were decreased by 35.8%, 36.5% and 16.5%, respectively. Although the phosphorus content of EP/BPD‐0.75 thermoset was lower than that of EP/DOPO thermoset, EP/BPD‐0.75 thermoset exhibited better flame retardancy than EP/DOPO thermoset. The significant improvement of flame retardancy of EP/BPD thermosets was ascribed to the blocking effect of phosphorus‐rich intumescent char in condensed phase, and the quenching and diluting effects of abundant phosphorus‐containing free radicals and nitrogen/sulfur‐containing inert gases in gaseous phase. There was flame‐retardant synergism between phosphorus, nitrogen, and sulfur of BPD.     

Synthesis of organo-modified α-zirconium phosphate and its effect on the flame retardancy of IFR poly(lactic acid) systems

Novel intumescent flame-retardant poly(lactic acid) (PLA/IFR)/organo-modified α-zirconium phosphate(OZrP) nanocomposites were prepared via incorporation of charring agent (CA), ammonium polyphosphate (APP) and OZrP into PLA. OZrP was synthesized directly by a solvent thermal method. The morphological characterization of PLA/IFR/OZrP nanocomposites was conducted by wide angle X-ray diffraction (WXRD) and transmission electron microscopy (TEM). The effect of the OZrP on flame retardancy and the thermal stability of PLA/IFR composites were studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test. The TGA data illustrated that the OZrP could increase the residue and significantly improve the flame retardancy of PLA/IFR/OZrP nanocomposites showing an excellent synergistic effect. The addition of OZrP to the flame-retardant PLA increases the LOI and enhances the UL-94 rating. Cone calorimeter tests gave clear evidence that the incorporation of OZrP into PLA/IFR composites resulted in the significant reduction of the heat release rate (HRR), low total heat release (THR) and high amount of char residues during combustion. The flame-retardant mechanism of PLA/IFR/OZrP nanocomposites may correspond to the intumescent flame-retardant mechanism and catalyzed carbonization mechanism caused by OZrP.     

A novel intumescent flame‐retardant LDPE system and its thermo‐oxidative degradation and flame‐retardant mechanisms

A carbonization agent, 3,9‐di (2‐hydroxyisopropyl)‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro‐[5,5]‐undecane (SPEPO), was synthesized from pentaerythritol (PER), phosphorus trichloride, formic acid, and acetone as raw materials. The structure of SPEPO was characterized by FTIR and ¹H‐NMR. As a carbonization agent and an acid source, SPEPO can form a novel intumescent flame‐retardant (IFR) system for low density polyethylene (LDPE) together with ammonium polyphosphate (APP) and melamine phosphate (MP). The flame retardancy and thermal behavior of the IFR system for LDPE were investigated by limiting oxygen index (LOI), UL‐94 test, and thermogravimetric analysis (TGA). When the weight ratio of SPEPO, APP, and MP is 7:7:1 and their total loading level is 30%, the IFR‐LDPE presents the optimal flame retardancy (LOI value of 27.6 and UL‐94 V‐0 rating). However, SPEPO, APP, or MP can only show a very poor flame‐retardant performance when used alone. This indicates that there is a synergistic effect among SPEPO, APP, and MP. TGA results obtained in air demonstrate that SPEPO has an ability of char formation itself, and the char residue of SPEPO can reach 24 wt% at 700°C. The IFR can change the thermal degradation behavior of LDPE, enhance T_max of the decomposition peak of LDPE, and promote LDPE to form char based on the calculated and the experimental data of residues. According to the results of Py‐GC/MS in combination with FTIR of the char residues at different temperatures, a possible flame‐retardant mechanism has been proposed. Copyright © 2008 John Wiley & Sons, Ltd.     

A novel intumescent flame retardant imparts high flame retardancy to epoxy resin

Intumescent flame retardant (IFR) has received the considerable attention ascribed to the inherent advantages including non‐halogen, low toxicity, low smoke release and environmentally friendly. In this work, a novel charring agent poly (piperazine phenylaminophosphamide) named as PPTA was successfully synthesized and characterized by Fourier transform infrared spectra (FTIR) and X‐ray photoelectron spectroscopy (XPS). Then, a series of flame‐retardant EP samples were prepared by blending with ammonium polyphosphate (APP) and PPTA. Combustion tests include oxygen Index (LOI), vertical Burning Test (UL‐94) and cone calorimeter testing,these test results showed that PPTA greatly enhances the flame retardancy of EP/APP. According to detailed results, EP containing 10 wt% APP had a LOI value of 30.2%,but had no enhancement on UL‐94 rating. However, after both 7.5 wt% APP and 2.5 wt% PPTA were added, EP‐7 passed UL‐94 V‐0 rating with a LOI value of 33.0%. Moreover, the peak heat release rate (PHRR) and peak of smoke product rate (PSPR) of EP‐7 were greatly decreased. Meanwhile, the flame‐retardant mechanism of EP‐7 was investigated by scanning electron microscopy (SEM), thermogravimetric analysis/infrared spectrometry (TG‐IR) and X‐ray photoelectron spectroscopy (XPS). The corresponding results presented PPTA significantly increased the density of char layer, resulting in the good flame retardancy.     

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.     

Flame retardant properties and mechanism of an efficient intumescent flame retardant PLA composites

The charring agent (CNCA‐DA) containing triazine and benzene rings was combined with ammonium polyphosphate (APP) to form intumescent flame retardant (IFR), and it was occupied to modify polylactide (PLA). The flame retardant properties and mechanism of flame retardant PLA composites were investigated by the limited oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis, microscale combustion calorimetry, scanning electron microscopy, laser Raman spectroscopy analysis and X‐ray photoelectron spectroscopy. The analysis from LOI and UL‐94 presented that the IFR was very effective in flame retardancy of PLA. When the weight ratio of APP to CNCA‐DA was 3:1, and the IFR loading was 30%, the IFR showed the best effect, and the LOI value reached 45.6%. It was found that when 20 wt% IFR was loaded, the flame retardancy of PLA/IFR still passed UL‐94 V‐0 rating, and its LOI value reached 32.8%. The microscale combustion calorimetry results showed that PLA/IFR had lower heat release rate, total heat release, and heat release capacity than other composites, and there was an obvious synergistic effect between APP and CNCA‐DA for PLA. IFR containing APP/CNCA‐DA had good thermal stability and char‐forming ability with the char residue 29.3% at 800°C under N₂ atmosphere. Scanning electron microscopy observation further indicated that IFR could promote forming continuous and compact intumescent char layer. The laser Raman spectroscopy analysis and X‐ray photoelectron spectroscopy analysis results indicated that an appropriate graphitization degree of the residue char was formed, and more O and N were remained to form more cross‐linking structure. Copyright © 2016 John Wiley & Sons, Ltd.     

磷杂菲类阻燃剂的合成及其与聚磷酸铵复合膨胀体系对环氧树脂的阻燃性能研究

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)、五硫化二磷(P2S5)为原料合成9,10-二氢-9-氧杂-10-磷杂菲-10-硫化物(DOPS),并将DOPS与聚磷酸铵(APP)组成复合阻燃剂,用于环氧树脂(EP)的阻燃改性.通过氧指数(LOI)、垂直燃烧(UL-94)、热失重(TGA)、锥形量热(CONE)和扫描电镜(SEM)等方法对改性后的环氧树脂的阻燃性能和阻燃机理进行了测试和分析.实验结果表明,DOPS/APP阻燃体系对EP具有很好的阻燃性能,且复配阻燃剂的阻燃效果比单一的阻燃剂阻燃效果好;其中,当阻燃剂的总添加量达到30%时即W_(DOPS)=10%、W_(APP)=20%时,阻燃EP复合材料的LOI值可达到29.2%,垂直燃烧等级达到UL-94 V-0级,残炭量可达49.3%.     

Synergistic effects of 4A zeolite on the flame retardant properties and thermal stability of a novel halogen‐free PP/IFR composite

The synergistic effects of 4A zeolite (4A) on the thermal degradation, flame retardancy and char formation of a novel halogen‐free intumescent flame retardant polypropylene composites (PP/IFR) were investigated by the means of limiting oxygen index (LOI), vertical burning test (UL‐94), digital photos, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), cone calorimeter test (CCT), laser Raman spectroscopy (LRS) and X‐ray photoelectron spectroscopy (XPS). It was found that a small amount of 4A could dramatically enhance the LOI value of the PP/IFR systems and the materials could pass the UL‐94 V‐0 rating test. Also, it could enhance the fire retardant performance with a great reduction in combustion parameters of PP/IFR system from CCT test. The morphological structures observed by digital and SEM photos revealed that 4A could promote PP/IFR to form more continuous and compact intumescent char layer. The LRS measurement, XPS and TGA analysis demonstrated that the compactness and strength of the outer char surface of the PP/IFR/4A system was enhanced, and more graphite structure was formed to remain more char residue and increase the crosslinking degree. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and properties of a phosphorus-containing flame retardant epoxy resin based on bis-phenoxy (3-hydroxy) phenyl phosphine oxide

A reactive phosphorus-containing compound, bis-phenoxy (3-hydroxy) phenyl phosphine oxide (BPHPPO) was first successfully synthesized to produce the phosphorus-containing flame retardant epoxy resin (BPHPPO-EP). The chemical structures were characterized from FTIR, MS, NMR spectra and elemental analyses. Thermal degradation behaviors and flame retardant properties of the cured epoxy resins were investigated from the thermogravimetric analysis (TGA) and the limiting oxygen index (LOI) test using 4,4′-diaminodiphenylsulfone (DDS) as curing agent. The high char yields and the high limiting oxygen index values were found to certify the great flame retardancy of this phosphorus-containing epoxy resin.     

Synergistic effects of aluminum hypophosphite on intumescent flame retardant polypropylene system

The effects of aluminum hypophosphite(AHP) as a synergistic agent on the flame retardancy and thermal degradation behavior of intumescent flame retardant polypropylene composites(PP/IFR) containing ammonium polyphosphate(APP) and triazine charring-foaming agent(CFA) were investigated by limiting oxygen index(LOI), UL-94 measurement, thermogravimetric analysis(TGA), cone calorimeter test(CONE), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). It was found that the combination of IFR with AHP exhibited an evident synergistic effect and enhanced the flame retardant efficiency for PP matrix. The specimens with the thickness of 0.8 mm can pass UL-94 V-0 rating and the LOI value reaches 33.5% based on the total loading of flame retardant of 24 wt%, and the optimum mass fraction of AHP/IFR is 1:6. The TGA data revealed that AHP could change the degradation behavior of IFR and PP/IFR system, enhance the thermal stability of the IFR and PP/IFR systems at high temperatures and promote the char residue formation. The CONE results revealed that IFR/AHP blends can efficiently reduce the combustion parameters of PP, such as heat release rate(HRR), total heat release(THR), smoke production rate(SPR) and so on. The morphological structures of char residue demonstrated that AHP is of benefit to the formation of a more compact and homogeneous char layer on the materials surface during burning. The analysis of XPS indicates that AHP may promote the formation of sufficient char on the materials surface and improve the flame retardant properties.