Flame retardancy of unsaturated polyester composites with modified ammonium polyphosphate,montmorillonite, and zinc borate

Ammonium polyphosphate (APP) was modified using a new method, where the resulting modified APP (MAPP) was obtained by mixing APP with unsaturated polyester resin (UPR). MAPP was more effective in improving the flame retardancy of UPR than APP which was due to the improved dispersion of MAPP in UPR composite. Then, the UPR composites were prepared based on dimethyl methylphosphonate, MAPP, montmorillonite, and zinc borate. Finally, the flame-retardant and mechanical properties of the UPR composites were analyzed using the limited oxygen index (LOI), thermogravimetric analysis, UL-94 vertical burning test, scanning electron microscopy, cone calorimetry, mechanical tests, and viscosity measurements. The LOI and UL-94 tests showed that the flame-retardant properties clearly improved with the addition of fillers in the UPR composites compared to pristine UPR. The synergistic effect of Si- and P-containing flame retardants in this composite resulted in the LOI value increasing from 18.9 to 31.3% and achieved the UL-94 V-0 rating. Moreover, the heat release rate was lower than the pristine UPR. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47180.     

Mechanical,thermal and combustion properties of intumescent flame retardant biodegradable poly (lactic acid) composites

ABSTRACT

Despite extraordinary mechanical properties and excellent biodegradability, poly (lactic acid) (PLA) still suffers from a highly inherent flammability, restricting its applications in the electric and automobile fields. Although a wide range of flame retardants have been developed to reduce the flammability, they normally compromise the mechanical strength of PLA. In this study, a series of composites based on PLA, have been prepared by melt-blending with intumescent flame retardants (IFRs). The morphology, thermal stability and burning behaviour of the composites were investigated using a scanning electron microscope–energy dispersive spectrometer (SEM–EDS), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), vertical burning (UL-94) and the cone calorimeter test (CCT). The LOI value reached 38.5% and UL-94 could pass V-0 for the PLA/IFR composite containing only 12 wt-% IFR. The dispersion of IFR in PLA was observed using SEM–EDS. A significant improvement in fire retardant performance was observed for the PLA/IFR composite from the CCT (reducing the heat release rate and the total heat release). More importantly, compared to pure PLA, the addition of IFR did not seriously deteriorate the mechanical properties of the material.     

改性赤泥协同膨胀型阻燃剂阻燃聚乙烯

以聚磷酸铵（APP）、季戊四醇（PER）和三聚氰胺（MEL）复配的膨胀型阻燃体系（IFR）为主要阻燃剂,表面改性后的赤泥（Ti-MRM）作为协效剂阻燃聚乙烯（PE）,采用熔融共混法制备PE基阻燃复合材料（PE/IFR-Ti-MRM）。通过热重分析仪（TGA）、垂直燃烧仪（UL-94）、极限氧指数测定仪（LOI）及扫描电镜（SEM）等对其热氧稳定性、燃烧等级、阻燃性能和残炭形貌进行了表征与分析。结果表明：加入改性赤泥的PE/IFR-Ti-MRM复合材料形成的炭层更加致密和连续,当最优配比时,复合材料的极限氧指数达到32.2,燃烧等级达到V-0级;而PE/IFR阻燃复合材料的极限氧指数只能达到27.5,燃烧等级为V-2级。     

Flammability,thermal stability,and mechanical properties of ethylene-propylene-diene monomer/polypropylene composites filled with intumescent flame retardant and inorganic synergists

Three kinds of inorganic particles, zinc borate (ZB), organic montmorillonite (OMMT), and expanded graphite (EG) as synergistic flame retardants, are incorporated into ethylene-propylene-diene monomer/polypropylene (EPDM/PP) composites filled with intumescent flame retardants (IFR). The effect of three synergistic flame retardants on the combustion, thermal stability, and mechanical properties of the EPDM/PP/IFR composites are investigated by limiting oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), scanning electron microscopy, mechanical property testing, and dynamic mechanical analysis (DMA). The results from LOI, UL-94, and CCT show that the synergistic effect of IFR with ZB and EG is better than IFR with OMMT in the flame retardant EPDM/PP/IFR composites. The TGA results indicate that the thermal stability and char residues of the composites is improved with the addition of inorganic particles, which is attributed to the formation of dense char layers to isolate heat flow. DMA results including storage modulus (G'), loss modulus (G"), and loss factor (tan δ) suggest that the composites with inorganic particles exhibit more rubber-filler interaction, which limits the movement of the rubber chains.     

Effect of gas-condensed phase synergistic system of 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide and polydopamine on flame retardancy of epoxy resin

Polydopamine (PDA) was prepared by using dopamine which has good charring ability. The PDA was used as an environmentally friendly flame retardant and combined with 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPO) to improve the flame retardancy of epoxy (EP) resin. The flame retardancy and thermal stability of EP composites were researched by UL-94 vertical burning, limiting oxygen index (LOI), cone calorimetry tests, and thermal gravimetric analyzer. Adding DOPO alone requires 6% to make EP obtain the UL-94 V0. If DOPO and PDA are combined, only 4% is needed to make EP obtain the UL-94 V0, which suggests that there is good synergistic effect between them. Moreover, the peak of heat release rate of EP/DOPO/PDA composites is less than that of EP/DOPO composites. The reactions among EP, DOPO, and PDA reduce the release of combustible gases at the early stage of degradation; at the same time, DOPO volatilize to the gas phase, quench the free radicals, and the combustion can be stopped. In addition, due to the decrease of the amount of PDA/DOPO, the EP composite can get a higher glass transition temperature, but due to the aggregation of PDA in EP, the tensile property of EP composite decreases.     

A novel bio-based charcoal-forming agent based on chitosan and phytate@Mg to improve the flame retardancy of poly(lactic acid)

A novel bio-based carbon forming agent (Mg@PA-CS) containing P and N elements was were synthesized using the complexation characteristics of chitosan (CS) and phytate (PA). The flame retardant behavior of poly(lactic acid) (PLA)/Mg@PA-CS/APP composites (addition of 20 wt% of different ratios of Mg@PA-CS and APP to polylactic acid composites) were investigated by the limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetry test (CCT), and thermogravimetric analysis (TGA). Due to the biphasic flame retardant and synergistic effect, since the 20 wt% flame retardant system (Mg@PA-CS:APP = 1:2), PLA composites passed the UL-94 test V-0 rating, reached 34% LOI value. The peak heat release rate (PHRR) and total heat release rate (THR) were reduced to 1/2 of the pure PLA, char residue could be as high as 11.49% at 800°C. Moreover, the flame-retardant mechanism of PLA composites during thermal decomposition was analyzed using a scanning electron microscope (SEM) and the coupling techniques of TGA linked with FT-IR (TG-FTIR).     

High-efficiency ammonium polyphosphate intumescent encapsulated polypropylene flame retardant

The flame retardant polypropylene containing the micro-envelope core-shell structure flame retardant, which encapsulated ammonium polyphosphate into melamine-formaldehyde resin and sodium silicate through in situ polymerization was prepared with polyamide 6, added as a carbon-forming agent. The composition of ammonium polyphosphate, encapsulated ammonium polyphosphate with melamine-formaldehyde resin and the micro-envelope core-shell structure flame retardant were characterized. The fire safety and thermal stability were investigated and showed an improvement including limiting oxygen index, thermogravimetric analysis, vertical burning tests, and microscale combustion calorimeter. The burned compounds were also studied to confirm the burning mechanism. The results showed the flame retardant performance had been greatly improved, while polyamide 6 had better char-forming effect. Besides, the water solubility of flame retardants and their influence on the mechanical properties of polypropylene were also investigated. The results on the effects of additives demonstrated a high efficiency flame retardant to polypropylene. A core-shell flame retardant that sodium silicate and melamine-formaldehyde resin-coated ammonium polyphosphate had been constructed. The effect of the built flame retardant system on the combustion performance of polypropylene was studied from the mechanism and performance. The LOI of the most flame retardant polypropylene reached 28.6%, and UL-94 reached the V-0 level.     

Synthesis and characterization of bio-based intumescent flame retardant and its application in polyurethane

A novel bio-based P-N containing intumescent flame retardant melamine starch phytate (PSTM) was prepared via the reaction of phytic acid starch ester with melamine and characterized by Fourier transform infrared, scanning electron microscopy and thermogravimetric analysis (TGA). The effects of PSTM on thermal properties and flammability of rigid polyurethane (PU) foams were analyzed by TGA, limit oxygen index (LOI), vertical burning tests (UL-94) and cone calorimeter measurement. The TGA results demonstrated that the thermal stabilities of PU/PSTM foam at high temperature was enhanced with the increasing additive amount of PSTM. The results showed that PU foam with 30 php PSTM (PU/PSTM-30%) observed an LOI value of 25.9 and a UL-94 rating of V-0. Cone calorimetry data showed that peak heat release rate, total heat release and smoke production rate of PU/PSTM-30% were distinctly lower than that of pure PU. Further experimental results demonstrated that PSTM promotes well charring of PU which could protect the foam from combustion. This work developed a novel bio-based intumescent flame retardant by suing phytic acid and starch as the acid source and carbon source, respectively, which is of great significance to the preparation of environmental-friendly flame retardants.     

有机磷阻燃剂HDP与HMP在聚碳酸酯中的应用

研究高熔点环保型有机磷阻燃剂对苯二酚双(二苯基磷酸酯)(HDP)与对苯二酚双[二(1-甲基-2-苯基)磷酸酯](HMP)在聚碳酸酯(PC)中的应用。结果表明,当阻燃剂质量分数为7%时,PC/HDP与PC/HMP的极限氧指数测试(LOI)值分别为30.4与30.6,相对于PC(28.0)有较大提升,并且垂直燃烧测试(UL-94)都通过了V-0级,拉伸强度提升约3.5 MPa,弯曲强度提升约8 MPa。热重(TG)曲线和热重微分(DTG)曲线表明,HDP与HMP都降低了PC材料的最大热分解速率,同时PC/HDP的成碳效果优于PC/HMP。     

Preparation,characterization and its flame retardance performance of microencapsulated ammonium polyphosphate/ bridged polysesquisiloxane polyurethane composites

A core shell material consisting of ammonium polyphosphate as core and 4,4-oxydianiline-formaldehyde resin as shell was prepared through a situ microencapsulation technology. The monomer of the polyurethane (PU) was modified to form bridged polysesquisiloxane. The purpose of modification is to improve the thermal stability of polyurethane matrix through the formation of networks. The degree of the networks was evaluated by solid state ²⁹Si-nuclear magnetic resonance. The structure and hydrophobic property of microencapsulated flame retardant were characterized using X-ray photoelectron spectroscopy and water solubility. The results indicated that the microencapsulation of APP with 4,4′-oxydianiline-formaldehyde resin (OF resin) resulted in improved hydrophobicity. The thermal properties of final flame retardant were systematically analyzed through thermogravimetric analysis. Limiting oxygen index and UL-94 test were used to classfied the flame retardant properties of varying the composition of APP and OFAPP in silanol-terminated polyurethane composites. Pure PU exhibited an LOI of 17 % and failed the UL-94 test. The LOI values of the 40 % OFAPP-added composites can reach 41 % and pass V-0 level. The results revealed that the microcapsulation of commercial flame retardant can improve the flame retardance of the composites.     

EG与IFR复合阻燃ABS的动态燃烧性和协同效应

将可膨胀石墨(EG)与P-N型膨胀阻燃剂(IFR)复合阻燃丙烯腈-丁二烯-苯乙烯共聚物(ABS)树脂,阻燃剂添加量为20%(质量分数,下同),通过极限氧指数(LOI)仪、垂直燃烧测试(UL-94)仪、锥形量热(CONE)仪和扫描电镜(SEM)研究了EG与IFR复合阻燃ABS的协同效应。结果表明,EG/IFR质量比为1/1为最佳配比,阻燃ABS的LOI达到29%,UL-94为V-0级;EG与IFR复合阻燃ABS,表现出一定的协同作用;通过SEM观察ABS/EG/IFR试样燃烧后样品发现,EG与IFR起到协同阻燃作用。     

An easy‐to‐obtain silicone‐containing flame retardant and its effects on the combustion of polycarbonate

A novel silicone‐containing flame retardant (HSOBA) synthesized from hydrogen‐containing silicone oil and Bisphenol A via a simple approach has been incorporated into polycarbonate (PC) matrix to study its effects on the flame retardancy. The flame retardancy of PC/HSOBA composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter measurement. The LOI value of the composites is 31.7 and the UL‐94 rating reaches V‐0, when the content of HSOBA is 3 wt %. Cone calorimeter data confirm that the HSOBA acts as an effective additive functioning both as flame retardants and as smoke suppressant. Evolution of the thermal behaviors of the composites tested by TGA, the morphological structures, and the constituent of char residue after LOI tests characterized by scanning electronic microscopy‐energy‐dispersive X‐ray analysis were used to explain the possible flame‐retardant mode. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

木质素与含磷阻燃剂对环氧树脂固化物阻燃性能的影响

利用不同质量比的木质素、苯酐（PA）、环氧树脂（EP）、2-（二苯基磷酰基）琥珀酸（DPPOSA）共固化制备出一系列环氧树脂固化物,采用极限氧指数测试、UL-94垂直燃烧评级测试、锥形量热仪热释放速率和总热释放量测试、空气条件下的热重分析测试和扫描电镜对环氧固化物进行测试和分析。当EP为90.0%、PA为6.5%、DPPOSA为2.0%、木质素为1.5%时制备的环氧固化物（P-12）的热稳定性能和阻燃性能得到了明显的改善。阻燃性能测试表明：其极限氧指数（LOI）达到34.6%,垂直燃烧测试通过UL-94的V-0级,热释放速率和热释放总量也有效降低;热降解测试结果表明：DPPOSA和木质素的加入可以使材料的降解时间提前,成炭能力增强;扫描电镜结果显示：添加DPPOSA和木质素的环氧固化物燃烧后形成连续、均一、紧密的炭层,进一步证明DPPOSA和木质素的加入使环氧固化物的成炭能力得到增强。     

PBT/TPU/DOPO-MA阻燃复合材料的制备及性能

通过使用9,10-二氢-9-氧杂-10-磷朵菲-10-氧化物（DOPO）和马来酸酐反应合成制备DOPO衍生物阻燃剂DOPO-MA,并且其结构使用傅里叶红外光谱分析（FTIR）和核磁共振氢谱分析（¹H NMR）技术进行表征。将阻燃剂与聚对苯二甲酸丁二醇酯（PBT）和热塑性聚氨酯（TPU）熔融共混以制备PBT/TPU/DOPO-MA阻燃复合材料。通过运用锥形量热、UL-94、极限氧指数（LOI）、热重分析（TGA）、差热分析（DSC）和力学测试,研究了阻燃剂对复合材料的性能影响。测试结果表明,PBT/TPU/DOPO-MA复合材料具有良好的阻燃性能,加入10％DOPO-MA后,LOI从23.2增加到31.6,可达到UL-94 V-1等级,热释放率峰值（PHRR）和最大成热辐射速率（MAHRE）值降低;热重分析测试结果表明,添加DOPO-MA可以使得阻燃复合材料的热稳定性有显著的提高,当加入10％DOPO-MA后,残炭量可从6.87增加到14.36。此外,随着DOPO-MA含量的增加,阻燃复合材料的结晶度可得到一定的提高。     

Improving the fire performance and smoke suppression of expandable polystyrene foams by coating with multi-dimensional carbon nanoparticles

Expandable graphite (EG) and modified multi-wall carbon nanotubes (ATH-MWNT) were introduced to expandable polystyrene (EPS) foams in order to improve its fire performance. The fire performance of EPS foams was evaluated by limiting the oxygen index (LOI), vertical burning (UL-94), and cone calorimetry tests. The results showed that the presence of 14.3% EG and 4.1% ATH-MWNT increased the LOI value from 18.0 to 30.3%, upgraded the UL-94 rating from no rating to V-0, completely eliminated melt dripping, and significantly decreased the peak heat release rate from 933 to 177 kW/m². Thermal analysis indicated that the thermal stability and char formation were improved by the presence of flame retardants. The char morphology was characterized by scanning electronic microscopy (SEM). It was suggested that the presence of EG and ATH-MWNT could form integrated char layers during combustion, which was beneficial to the formation of an intumescent protective char structure.     

Vinyl polysiloxane microencapsulated ammonium polyphosphate and its application in flame retardant polypropylene

Vinyl polysiloxane microencapsulated ammonium polyphosphate (MAPP) was prepared by a sol-gel method using vinyltrimethoxysilane as a precursor to improve its thermal stability and hydrophobicity. The MAPP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and thermogravimetric analyzer (TGA). The results showed that ammonium polyphosphate (APP) was successfully coated with vinyl polysiloxane. MAPP and pentaerythritol (PER) were used together to improve the flame retardancy of polypropylene (PP). The flame retardant properties of PP composites were investigated by limiting oxygen index (LOI), UL-94 test, TGA and SEM. When the MAPP was added as a flame retardant, with PER as a char forming agent, the LOI of PP/MAPP/PER composites was 33.1%, and it reached the UL-94 V-0 level. The results also demonstrated that the flame retardant properties of PP/MAPP/PER composites were better than those of PP/APP/PER composites at the same loading. Moreover, the addition of flame retardant and carbon forming agent could promote the crystallization behavior of PP.     

Effect of phosphorus–nitrogen compound on flame retardancy and mechanical properties of polylactic acid

A phosphorus-nitrogen flame retardant (PN) was synthesized by using cytosine and diphenylphosphinic chloride. The flame retardancy and thermal stability of polylactic acid (PLA)/PN composites were investigated by the UL-94 vertical burning test, limited oxygen index (LOI), cone calorimeter test, and thermogravimetric analysis. The PN performs efficiently on improving the flame retardancy of PLA. The PLA composite achieves the UL-94 V-0 rating and its LOI increases to 30.4 vol% by adding 0.5 wt% PN. The flame retardant mechanism analysis showed that PN catalyzes the degradation of PLA to improve the flame retardancy by melting-away mode. Meanwhile PN reduces the release of flammable gasses during thermal degradation of PLA by promoting the transesterification of PLA, which is helpful for extinguishing flame. Moreover, triglycidyl isocyanurate (TGIC) was used as a micro-crosslinking agent to reduce the loss of mechanical properties of PLA/PN composites caused by degradation. Adding 0.1 wt% TGIC and 1.0 wt% PN into PLA, the tensile strength and elongation at break of PLA/PN are increased to the same level as that of PLA. Therefore, PLA with excellent comprehensive performance can be obtained.     

卡拉胶-纳米氢氧化铝协同阻燃天然橡胶

将BaCl2分级的k型卡拉胶(KC)和纳米氢氧化铝〔Al(OH)3〕构成的协同阻燃体系添加到天然橡胶(NR)中制备KC-Al(OH)3/NR复合材料。通过TG、极限氧指数(LOI)、锥形量热(CCT)以及SEM考察了不同质量比的KC和Al(OH)3对复合材料力学性能和阻燃性能的影响。结果表明,当KC与Al(OH)3以1∶1的质量比加入到NR时,KC-Al(OH)3/NR复合材料的热稳定性、阻燃性能最优,复合材料的LOI达到25%。与纯天然橡胶相比,复合材料总热释放量(THR)、热释放速率峰值(pHRR)、总烟释放量(TSP)和平均质量损失率(AMLR)分别降低了12%、65%、23%和62%。相比于单独添加Al(OH)3体系,复合材料拉伸强度和断裂伸长率分别增加了11%和17%。     

Influence of nano silica hybrid expandable graphite on flammability,thermal stability,and mechanical property of polypropylene/polyamide 6 blends

Silica (SiO₂) nanohybrid expandable graphite (nEG) particles fabricated through one-step method are used as an efficient flame retardant for polypropylene (PP)/polyamide 6 (PA6) blends. The effect of nEG on the flammability, thermal stability, crystallization behaviors, and mechanical properties of PP/PA6 composites is investigated by using limit oxygen index (LOI), UL-94 test, cone calorimeter test (CCT), thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared, scanning electron microscopy, and mechanical tests. Compared with pure expandable graphite (EG), nEG improves the flame retardancy of composites. The results of LOI show that LOI of PP/PA6/nEG10 and PP/PA6/nEG15 composites are 26.0% and 27.2%, respectively. But the LOI values of PP/PA6/EG10 and PP/PA6/EG15 composites are 25.7% and 26.9%, respectively. The UL-94 test results show that PP/PA6/nEG10 composites reach V-1 level when the nEG content is only 10%. However, the PP/PA6 composites with 10% EG does not pass the UL-94 test. In addition, PP/PA6 composites with 15% nEG can reach V-0 level. The CCT results further show that nEG has a higher flame-retardant efficiency than pure EG for PP/PA6 blends. The thermal stability of PP/PA6/nEG composites is better than that of PP/PA6/EG composites. The mechanical property tests indicate that nEG is more conducive to maintain the tensile and impact strengths of PP/PA6 blends than EG due to the enhanced compatibility and interfacial adhesion.     

Synergistic flame retardant effects of Fe-OMMT with LDH in EVA/LDH composites

Abstract

The synergistic effects of Fe organic modified montmorillonite (Fe-OMMT) with layered double hydroxides (LDHs) in ethylene vinyl acetate copolymer/LDH (EVA/LDH) composites have been studied using thermal analysis [thermogravimetric analysis (TGA)], limiting oxygen index (LOI), UL-94 test and cone calorimeter test (CCT). The results showed that the addition of a given amount of Fe-OMMT apparently increased the LOI value and the rating in the UL-94 test. The results from the LOI and UL-94 tests show that Fe-OMMT can act as flame retardant synergistic agents in EVA/LDH composites. The CCT data indicated that the addition of Fe-OMMT in the EVA/LDH system can greatly reduce the heat release rate. The TGA data show that Fe-OMMT, as an excellent flame retardant synergist of LDH, cannot increase the thermal degradation temperature and the charred residues.