PP/EVA/OMMT纳米复合材料及其阻燃材料的动态燃烧行为

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/乙烯-醋酸乙烯酯共聚物(EVA)/有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/EVA/OMMT/氢氧化铝(ATH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加5%(质量分数)OMMT可以提高PP/EVA复合材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且OMMT与无卤复配阻燃剂之间可产生阻燃协同作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。     

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.     

聚磷酸铵-苯并噁嗪微胶囊的制备及其对环氧树脂燃烧性能影响

以多聚甲醛、丙烯胺、苯酚为原料,通过Mannich反应合成烯丙基型苯并噁嗪单体(Bala),并通过核磁共振氢谱(~1H-NMR)确定了其化学结构.将Bala在聚磷酸铵(APP)原位开环聚合后,制备APP微胶囊(BMAPP).傅里叶变换红外(FTIR)和静态接触角测试表明,Bala在APP表面成功聚合,并有效提高APP的疏水性,与纯APP相比,BMAPP的接触角从10.8°提高到了71.3°.将BMAPP添加到环氧树脂(EP)中,制备EP/BMAPP复合材料.通过热重分析仪(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥型量热仪(CONE)和动态热机械分析仪(DMA)对EP和EP/BMAPP的热性能以及燃烧性能进行对比分析.结果显示,10%的BMAPP的成炭效果最佳,有良好的阻燃性能,可使EP的LOI值从22.6%提高到33.6%,并通过UL-94 V-0级,600°C下残炭率达26.3%.同时,BMAPP可大幅度降低EP燃烧过程中烟密度和热释放速率,提高EP的玻璃化转变温度(T_g).BMAPP/EP-10%中,PBala和APP协同后使EP热释放速率峰值(PHRR)由1247 kW·m~(-2)降低到434 kW·m~(-2),生烟速率(SPR)降低67%左右,T_g从169°C提高到了173°C.     

用锥形量热仪研究聚乙烯膨胀阻燃体系的燃烧性

利用锥形量热仪在50kW·m^-2热辐照条件下,研究了含淀粉膨胀阻燃线性低密度聚乙烯(LLDPE)体系的燃烧性,获得了最大热释放速率、总热释放、有效燃烧热、最大烟产生速率、总烟释放量及质量损失速度等参数.实验结果表明:含淀粉膨胀阻燃剂能明显降低LLDPE的热释放速率、总热释放和有效燃烧热,淀粉作为膨胀型阻燃剂中的成炭剂,可以部分代替季戊四醇,而对热释放速率影响不大,达到了阻燃和降低成本的目的.该膨胀体系使烟释放变得缓慢,但总烟释放量明显增大.在燃烧时使LLDPE更早地发生热降解,但热降解速度变得缓慢.     

改性纳米二氧化硅在环氧树脂膨胀阻燃体系中的协效作用研究

以膨胀阻燃剂(IFR)为主要阻燃剂,以纳米二氧化硅(Nano-SiO_2)及KH570改性纳米二氧化硅(SiO_2-gKH570)为协效剂制备阻燃环氧树脂(EP)材料,对比研究了2种EP/IFR/SiO_2及EP/IFR/SiO_2-g-KH570体系材料的阻燃性能、力学性能、热量释放、烟气释放、热降解行为及炭层表面形貌。结果表明,当阻燃剂的总添加量为环氧树脂基体质量分数的30%(SiO_2为IFR质量的10%)时,SiO_2与IFR具有阻燃协同效应,在同样的添加比例下,改性的SiO_2会增强这种协同作用。EP/IFR/SiO_2-g-KH570体系与EP/IFR/SiO_2体系相比,两者氧指数(LOI)分别为30.2%和28.6%,UL-94测试分别通过V-0和V-1级; EP/IFR/SiO_2-g-KH570的力学性能较EP/IFR/SiO_2也有所提高,弯曲强度和抗冲击强度分别提高了10.2MPa和0.6KJ·m~(-2);锥形量热及热分析结果表明,EP/IFR/SiO_2-g-KH570体系在热释放、CO和CO_2释放指标上数值明显降低,热稳定性增加;残炭的电镜形貌分析表明,EP/IFR/SiO_2-g-KH570体系能形成更加致密和连续的炭层,能起到很好的物理屏障作用,显示出较好的阻燃效果。     

膨胀阻燃硬质聚氨酯泡沫塑料热降解及燃烧产烟研究

采用热失重、X-射线光电子能谱分析、氧指数及烟密度测试等方法研究了可膨胀石墨(EG)与聚磷酸铵(APP)复配膨胀阻燃硬质聚氨酯泡沫塑料(RPUF)的热降解、燃烧性能及产烟行为.在此基础上利用锥形量热仪考察了EG/APP对磷酸三(β-氯异丙基)酯(TCPP)阻燃RPUF体系燃烧性能的影响.研究表明,EG与APP间的相互作用导致了EG/APP体系高温阶段失重速率下降、残炭量显著上升;EG/APP与RPUF之间的成炭作用以APP的化学成炭为主.与RPUF比较,RPUF/EG/APP的氧指数由19.8%提高至35.4%的同时,烟密度没有显著上升.对比EG、APP及EG/APP阻燃RPUF,体系残炭量越高、炭层耐热氧化能力越强,氧指数就越大;残炭表面越致密,产烟量就越少.添加EG/APP可显著降低含卤体系RPUF/TCPP的热释放、烟释放及CO释放速率,体现了EG与APP复合体系物理与化学膨胀结合的优势.     

三聚氰胺聚磷酸盐/季戊四醇配比、协效剂组及表面改性对聚丙烯基木塑复合材料的膨胀阻燃影响

通过极限氧指数(LOI)、线性燃烧速率(LBR)、热重分析和锥形量热分析等技术手段研究膨胀型阻燃剂(IFRs)中三聚氰胺聚磷酸盐(MPP)和季戊四醇(PER)的质量比、组成为m(MgO):m(可膨胀石墨,EG):m(SiO₂)=1:5:5的协效剂组(MgO/EG/SiO₂)和硅烷偶联剂(KH550)对聚丙烯基木塑复合材料(WPC)阻燃性能的影响。 结果表明,当IFRs中m(MPP):m(PER)=23:2(IFRs-M1)、质量分数为25%时的阻燃性能最佳,膨胀阻燃复合材料WPC/IFRs-M1的LOI和LBR分别为27.1%和3.89 mm/min,较未添加的WPC分别提高48.1%和下降89.79%,燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了76.2%、50.1%、6.9%和65.4%,600 ℃时的残炭率提高了498.3%。 协效剂组和KH550表面处理均可进一步改善WPC/IFRs-M1的阻燃性能,均对IFRs-M1具有良好的阻燃增效作用。 相比于WPC/IFRs-M1,同时用这两种阻燃增效手段的WPC/IFRs-M1/MgO/EG/SiO₂/KH550,其LOI提高了3.7%,LBR降低了20.3%;材料的热稳定性明显提高,热失重降低;燃烧时的热释放速率、总热释放量、总烟释放量和CO₂释放量分别降低了36.5%、37.6%、57.5%和33.33%,600 ℃时的残炭率提高了84.02%,显示出二者更好的协同效应。     

聚甲基丙烯酸甲酯等温燃烧反应的动力学研究

使用锥形量热仪研究了3 mm厚、 100×100 mm2的透明聚甲基丙烯酸甲酯(PMMA)板在不同温度下的燃烧反应,采用化学动力学法拟合了PMMA燃烧过程中质量损失率a与时间t的单方程速率模型.结果显示,在PMMA燃烧过程中,质量损失速率受产物的解吸附和扩散过程控制.PMMA在584～800℃燃烧时,合适的反应动力学方程为[-ln(1-a)]1/4=Ae-E/RT t,其中指前因子A约等于0.1239 s-1,平均表观活化能E约为22.81 kJ/mol,并与温度的变化基本无关,计算结果与实验数据吻合较好.     

协效阻燃聚丙烯的阻燃性能

本文研究了以聚磷酸铵(APP)为主阻燃剂,次磷酸铝(AHP)和三聚氰胺氰尿酸盐(MCA)为辅阻燃剂的协效阻燃体系对聚丙烯(PP)阻燃性能的影响。 采用垂直燃烧测试、极限氧指数(LOI)测试、热重分析、锥形量热仪测试、扫描电子显微镜分析等技术手段对所制备的阻燃样品进行了阻燃性能分析。 结果表明:单独添加任一质量分数30%阻燃剂,均不能使PP获得良好的阻燃性能;当阻燃剂总质量分数保持在30%,m(APP)：m(AHP)：m(MCA)=4：1：1时获得理想阻燃效果,此时阻燃PP的LOI为33%,垂直燃烧测试达到V-0级,热释放速率峰值(PHRR)从765.7 kW/m²降为122.7 kW/m²。     

贫煤O_2/CO_2气氛下燃烧时内在矿物质对SO_2和NO_x排放特性的影响

利用管式炉反应器在550-1 000℃对长治贫煤和脱矿物质煤分别在空气和O_2/CO_2气氛进行了燃烧实验。利用XRF、XRD等分析手段,对煤样的基本性能进行了分析表征,并采用热分析仪(TG-DTG)以及傅里叶红外气体分析仪(AntarisIGS)对贫煤燃烧过程中的燃烧特性和SO_2和NO_x释放规律进行了研究。结果表明,与原煤相比,脱矿物质煤的着火温度和燃烬温度有所降低;O_2/CO_2气氛下,原煤和脱矿物质煤的着火温度和燃烬温度都升高,说明当O_2浓度为20%时,空气气氛比O_2/CO_2气氛更易于着火和燃烬。此外,与长治原煤相比,脱矿物质煤在相同条件下燃烧时SO_2的释放量明显提高,而NO_x的释放量却有所降低。O_2/CO_2气氛下原煤燃烧时SO_2浓度比空气气氛下的要高,而脱矿物质煤燃烧时释放的SO_2浓度明显比空气气氛下的低;O_2/CO_2气氛下原煤和脱矿物质煤燃烧时释放的NOx浓度比空气气氛下燃烧时释放的NO_x浓度要低。     

Characterization of ignition and combustion characteristics of phenolic fiber-reinforced plastic with different thicknesses

The present study focuses on ignition and combustion characteristics of phenolic fiber-reinforced plastic (FRP) with different thicknesses under different external heat fluxes using cone calorimeter, which receives little attention to date. A series of parameters including ignition time, thermal thickness, mass loss factor, mass loss rate (MLR), heat release rate (HRR), total heat release (THR), fire performance index (FPI) and fire growth index (FGI) are measured or calculated. Results indicate that the ignition time increases with the thickness, but decreases with the external heat flux. Phenolic FRP with thickness of 3 mm may be considered as thermally thin material. However, phenolic FRP with thickness of 5 and 8 mm is prone to be thermally thick material. The critical heat flux, minimum heat flux and ignition temperature are deduced and validated. The thermal thickness increases with the external heat flux. Linear correlations of the thermal thickness with the ratio of specimen density and external heat flux are demonstrated and presented. The mass loss factor decreases with the thickness. Three and two peak MLRs occur in the cases of low and high external heat fluxes, respectively. The average MLR increases with the external heat flux and thickness. The average and maximum HRR increases with the external heat flux. The FGI for the maximum HRR increases with the external heat flux. Linear correlations of the average MLR, the average and maximum HRR and the FGI for the maximum HRR with the external heat flux are demonstrated and presented.

     

Evaluate the flammability of a PU foam with double-scale analysis

Two-scale tests, microscale and bench scale, are conducted to analyze the flammability of a flexible polyurethane foam. Microscale tests include simultaneous thermal analysis coupled to Fourier transform infrared spectroscopy, and microscale combustion calorimeter (MCC). Evolved gas components, heat release rate per unit mass, total heat release, derived heat release capacity, and minimum ignition temperature are obtained. Bench scale tests are performed on cone calorimeter. Peak heat release rate per unit area, effective heat of combustion, minimum incident heat flux for ignition, and total heat release per unit area of different incident heat fluxes are obtained. FO-category of the PU foam is estimated by multiple discriminant function analysis based on the results of cone calorimeter test. The relationship between the two-scale tests is analyzed. The minimum ignition temperatures derived from multi heating rate MCC tests are used to predict the time to ignition and compared with the results from cone calorimeter tests. This PU foam is evaluated as a high fire hazard polymer having low heat release capacity, low ignition temperature, and short ignition time.

     

Experimental study of woods under external heat flux by autoignition

Piloted ignition of woods has been commonly investigated, which is accelerated by a spark plug. Autoignition is a complex phenomenon that combustible materials are ignited by internal heating, without the spark plug. Compared with piloted ignition, process of autoignition is closer to the development of real fire. Very few studies have focused on the prediction of ignition time and average mass loss rate by autoignition. Therefore, ignition time and mass loss rate on six species of commonly used wood samples, namely pine, beech, cherry, oak, maple, and ash, were studied under external heat flux by autoignition in a cone calorimeter. Three mass loss stages of woods under external heat flux was observed. Empirical models of ignition time and average mass loss rate for woods under external heat flux were developed. These empirical models can be used not only for fire risk evaluation, but also for modeling input and validation.     

Fire reaction properties of polystyrene-based nanocomposites using nanosilica and nanoclay as additives in cone calorimeter test

Using nanofiller additives in the polymer matrix to form nanocomposites is a potential way of reducing the flame spread and enhancing flame retardancy of polymeric materials during fire. To understand the fire reaction properties and the relative performance of flame-retardant additives in polymer during well-developed fire, neat polystyrene, polystyrene–silica and polystyrene–nanoclay (MMT) have been tested in a cone calorimeter. The neat polystyrene and the polystyrene nanocomposites have been prepared via an in situ polymerization method. An external heat flux of 50 kW m^?2 was applied in the test, and parameters such as heat release rate, peak heat release rate, time to ignition, smoke toxicity, CO and CO₂ yield have been investigated. Both neat polystyrene and polystyrene nanocomposites have shown the trend of a thermally thick charring polymer in the heat release rate over time data. The nanocomposites had an overall better flame retardancy than the neat polystyrene in terms of lower peak heat release rate, lower average mass loss rate and enhanced char formation. The nanocomposites had also reduced smoke emission with lower CO and CO₂ yield compared to the neat polystyrene. The overall flame retardancy was enhanced as the nanofiller loading was increased for both the nanosilica and MMT nanocomposites.

     

Fire hazard assessment on polyurethane sandwich panels for temporary accommodation units

Fire hazard assessment on sandwich panels used for constructing temporary accommodation units (TAUs) is discussed. The requirements imposed by the three responsible local government departments, i.e. Buildings Department, Fire Services Department and Labour Department, are outlined. A typical sandwich panel used for constructing TAUs was assessed by a cone calorimeter. Four radiative heat fluxes of 20, 25, 50 and 65 kW m⁻² were applied to study the sustained ignition time, peak heat release rate, average heat release rates in 60 and 180 s after ignition, total heat release rate, mass loss percentage, total smoke release, carbon monoxide and carbon dioxide yields. From these data, the possibilities of flashover and smoke aspects were studied. Preliminary recommendations on what should be considered in specifying fire tests for new regulations on the use of these sandwich panels are made.     

Ignition and burning behaviors of automobile oil in engine compartment

Accidental leakage of automobile oils is of great inclination to initiate pool fires in engine compartment, with threats to induce the flashover of other components and flame penetration into the passenger compartment. This paper presents experimental results of the ignition and burning behaviors of a kind of automobile oils (automatic transmission oil) using a cone calorimeter. Measurements of oil temperature, ignition time, mass loss and heat release rate are performed at different external heat fluxes and initial fuel depths. The comparison between experimental and numerical oil temperature evolutions shows that the variations of the ignition time at different experimental conditions depend on the heat dissipation process inside the liquid phase. The steady mass burning rate is nearly independent of initial fuel depth and has a linear relation with external heat fluxes. In addition, the results indicate an increase in peak heat release rate by a large margin initially, followed by a relatively small margin under thicker initial fuel depths, while its variations are proportional to external heat fluxes. Correlations are also developed to determine the peak heat release rate as a function of the initial fuel depth.

     

An assessment of petrol fire risk by oxygen consumption calorimetry

This article evaluates the fire risk of petrol utilising a novel testing procedure that enables the measurement of heat release rate (HRR), specific mass loss rate and carbon monoxide (CO) yield of flammable liquids in a cone calorimeter. The testing procedure is a modification of the procedure described in ISO 5660-1:2002. The modification includes the use of a sample pool enabling the testing of flammable liquids. Pure petrol samples were tested. They were ignited with a spark igniter, without the use of a cone heater. The cone heater was removed before testing to avoid its heating by the flame and consequent heat radiation onto the tested sample surface. The average HRR was 612 kW m^?2 and the maximum HRR was 842 kW m^?2. The total CO yield related to mass loss was 58.6 g kg^?1 and related to the effective heat of combustion was 1.48 g MJ^?1. The immediate CO yield increased significantly with an increase in testing time (an increase in the depth level of liquid below the upper edge of the pool). Dependence equations of HRR and specific CO production rate (SCPR) on the specific mass loss rate were calculated from the obtained data. Substituting the specific mass loss rate of petrol (55 g m^?2), which burns in an infinite diameter pool, the HRR (1,581 kW m^?2) and SCPR (3.99 g m^?2 s^?1) were calculated for petrol pool fire under real conditions (at pool diameter larger than 1.5 m). The calculated SCPR accounted for a CO yield of 72.55 g kg^?1.     

Investigation on effects of thickness on ignition characteristics and combustion process of the oil-impregnated transformer insulating paperboard

Effects of thickness on ignition characteristics and combustion process of the oil-impregnated transformer insulating paperboard were investigated experimentally by cone calorimeter. Five thicknesses of transformer insulating paperboard, including 0.5, 1.0, 1.5, 2.0 and 3.0 mm were taken into account together with five radiation intensities between 25 and 80 kW m^?2. According to the experimental results on ignition characteristics, the 0.5-mm paperboard for all radiation intensities and the 1.0-mm paperboard with the radiation heat flux less than 35 kW m^?2 were thermal thin material. The 1.0-mm paperboard under higher radiation intensities and the paperboard with the thicknesses of 1.5, 2.0 and 3.0 mm were thermal thick material. The heat release rate (HRR) of oil-impregnated transformer insulating paperboard decreased with its thickness. Due to the different pyrolysis processes, the number of HRR peaks increased with the thickness of paperboard. The CO and CO₂ production rate and the O₂ consumption rate were all decreased with the paperboard thickness basically. There was an increase in the CO production rate at the end of fire duration, since the incomplete combustion process occurred at this stage. The increase in the CO production rate was more obvious in the experiments under lower external radiation heat fluxes.     

A novel exploration of metal–organic frameworks in flame-retardant epoxy composites

In this work, a series of transition metal–organic frameworks (MOFs) were prepared through self-assembly of organic bridging ligands and transition metal ions. The structure of MOFs samples was analyzed by XRD, FTIR, TG, and TEM. The influences of MOFs on flame resistance, toxicity reduction, and smoke suppression of epoxy were explored in detail. The findings presented that low addition amount of MOFs had a positive effect on decreasing the fire hazards of epoxy. Loading of 2 mass% MOFs into epoxy led to the decrease in thermal degradation rate and increase in char yields. Meanwhile, the values of peak heat release rate, total heat release, and average mass loss rate of epoxy composites were cut down effectively, in comparison with neat epoxy. Moreover, the remarkable decrease in smoke production rate, total smoke production, and CO, CO₂ yield could be provided by cone calorimeter test. The char residues after cone calorimeter test were investigated by SEM and Raman spectra, and the flame-retardant mechanism was discussed.