海泡石对膨胀阻燃聚丙烯燃烧和热分解的影响

将改性后的海泡石添加到聚磷酸铵(APP)和双季戊四醇(DPER)膨胀阻燃聚丙烯(PP/IFR)体系中,采用氧指数(LOI)、热重分析(TGA)、光电子能谱(XPS)、傅里叶变换红外(FTIR)光谱、锥形量热仪(CONE)和扫描电镜(SEM)考察其对膨胀阻燃体系的催化协效作用,探讨作用机理.LOI结果表明,改性的海泡石比纳米水滑石和有机改性的蒙脱土有更好的催化协效作用.CONE数据证实,海泡石可以降低膨胀阻燃聚丙烯体系的热释放速率和总的热释放量.通过观察SEM图片发现,海泡石可以改善膨胀炭层的形貌,提高炭层的隔热隔质性能.TGA结果表明,在氮气和空气气氛下,海泡石均可以提高膨胀炭层的热稳定性,增加高温时残余物的量,其主要作用对象为APP.FTIR和XPS测试发现加热过程中海泡石可以与APP发生化学反应,形成P—O—Si键,增加了APP高温时的稳定性.     

有机蒙脱土/天然橡胶纳米复合材料的阻燃性能研究

采用机械混炼插层法制备有机蒙脱土/天然橡胶(TMT/NR)纳米复合材料.使用X-射线衍射(XRD)和红外表征了有机蒙脱土的结构特性,并用锥形量热仪测试了纳米复合材料的燃烧性能.结果表明,有机蒙脱土/NR纳米复合材料的热释放速率(HRR)、生烟速率(SPR)等较纯天然橡胶、未改性蒙脱土/NR复合材料均所有降低,表现出较好的阻燃性能.通过对纳米复合材料的燃烧性能和燃烧残余物分析,探讨了该体系的阻燃机理.     

氢化丁腈橡胶/聚甲基丙烯酸镁/有机蒙脱土纳米复合材料制备及其耐介质老化性能

采用原位聚合和混炼插层相结合技术制备了氢化丁腈橡胶/聚甲基丙烯酸镁/有机蒙脱土(HNBR/PMgMA/OMT)纳米复合材料,通过XRD,SEM和TEM等测试方法研究了HNBR/PMgMA/OMT纳米复合材料的结构、形态和性能.PMgMA离子簇与未反应完全的MgMA单体形成纳米-微米共存形态结构,PMgMA对HNBR有显著的增强效果,HNBR/PMgMA/OMT纳米复合材料具有良好的加工性能、物理机械性能和耐介质老化性能.TEM结果显示MgMA/OMT并用有助于OMT剥离分散,有机蒙脱土在硫化胶中形成以剥离和插层为主、反插层和未插层共存的微观结构;SEM显示当MgMA/OMT用量为20/10份时能明显改善复合材料的界面结合,此时纳米复合材料的拉伸强度、扯断伸长率和扯断永久变形分别为30.2 MPa,520%和30%;同时具有优异的耐热空气和耐油老化性能,耐热水性能也明显改善,在165℃的热空气、水和油中长期老化14天的老化系数分别达到0.61,0.63和0.84,其耐介质老化性能明显好于炭黑增强HNBR硫化胶及HNBR/PMgMA复合材料.良好的蒙脱土片层分散结构是提高HNBR/PMgMA/OMT纳米复合材料耐介质老化性能的主要原因.     

酸碱处理蒙脱土与磷酸酯阻燃剂复配阻燃PC/ABS合金

采用酸碱处理法对蒙脱土进行有机化改性, 再将酸碱处理的蒙脱土与磷酸酯阻燃剂复配, 作为聚碳酸酯/丙烯腈-丁二烯-苯乙烯三元共聚物(PC/ABS)合金的阻燃体系, 并表征了酸碱处理蒙脱土对合金的热稳定性和阻燃性能. 结果表明, 间苯二酚双(二苯基磷酸酯)改性的蒙脱土(BDP-MMT)使阻燃PC/ABS合金的起始分解温度降低, 而酸碱处理蒙脱土却使合金的起始分解温度有所提高; BDP-MMT的加入会恶化碳层的阻隔性能, 而酸碱处理蒙脱土却可以增加碳层的稳定性, 使第二热释放峰值出现的时间延迟, 且适合的酸浓度处理蒙脱土可以使合金通过UL-94 V-0级检验.     

酸酐固化环氧树脂/蒙脱土复合材料的等温固化动力学

用等温差示扫描量热法(DSC)研究了酸酐固化环氧树脂/蒙脱土复合材料的等温固化过程，考察了未处理的蒙脱土(MMT)和有机蒙脱土(OMMT)对环氧树脂固化动力学的影响. 实验表明， 环氧树脂的固化过程包含自催化机理，加入蒙脱土没有改变固化反应机理. 用Kamal方程对该体系的固化过程进行拟合，得到反应级数m、n，反应速率常数k1、k2，总反应级数(m + n)在2.4～3.0之间. MMT的加入使环氧树脂体系的k1、k2有所降低，而OMMT的加入对体系的k1、k2影响较为复杂，加入蒙脱土对环氧树脂固化体系的活化能影响较小.     

双功能催化体系制备聚丙烯/蒙脱土复合材料

为了制备聚丙烯/蒙脱土纳米复合材料,将Brookhart型的乙烯齐聚催化剂负载于有机蒙脱土片层间,进一步与丙烯聚合茂金属催化剂进行复配得到双功能催化体系。采用这种双功能催化剂体系通过催化乙烯齐聚得到α-烯烃/蒙脱土的齐聚产物,进一步将丙烯与这种齐聚产物共聚,合成了一系列结构不同的聚丙烯/蒙脱土纳米复合材料。通过气相色谱、X射线衍射(XRD)分析得出蒙脱土负载的铁系催化剂催化乙烯齐聚产物是以C_4~C_(16)为主的α-烯烃,蒙脱土以片层形式分散于齐聚产物的甲苯溶液中。研究了蒙脱土负载的铁系催化剂与共聚催化剂复配催化乙烯齐聚以及丙烯与齐聚产物共聚合的情况。通过XRD、透射电镜、差示量热分析、凝胶渗透色谱分析表征可知,蒙脱土以纳米片层剥离的形式均匀分散于聚丙烯基体中,聚丙烯/复合材料的结晶温度比纯聚丙烯有所下降,所得聚丙烯基体分子量在8.1×10~4~17.1×10~4g/mo L。     

尼龙6/蒙脱土纳米复合材料非等温结晶动力学和透明性研究

将有机化的蒙脱土与尼龙6(PA6)在Haake共混机中共混,制备出尼龙6/蒙脱土纳米复合材料(PA6N);对尼龙6/蒙脱土纳米复合材料和纯尼龙6分别进行差示扫描量热法非等温结晶试验,以了解蒙脱土在尼龙6/蒙脱土纳米复合材料中的成核作用、扩大尼龙6在包装领域的应用范围.与此同时,采用偏光显微镜测定了样品的结晶形态;采用紫...     

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.     

MPP/PER/APP系统阻燃的PA6/OMMT纳米复合材料的燃烧特性

以聚磷酸蜜胺(MPP)／季戊四醇(PER)／聚磷酸铵(APP)三元膨胀型阻燃剂(IFR)(其中P／PER／三聚氰胺(MA)的摩尔比为4．1／1．0／1．1)对聚酰胺6(PA6)／有机蒙脱土(OMMT)纳米复合材料(wOMMT=0．03)进行阻燃，测定了阻燃PA6／OMMT的极限氧指数(LOI)及垂直燃烧阻燃性(UL94)，以锥形量热仪(CONE)测定了材料诸多与火灾安全性有关的阻燃参数，包括释热速率、有效燃烧热、总释热量、质量损失速率、比消光面积及引燃时间等，并与PA6、阻燃PA6及PA6／OMMT进行了比较，用扫描电镜(SEM)观察了由CONE测试所得残炭的形态。     

原位聚合制备聚乙烯/蒙脱土(MMT)纳米复合材料的研究

利用MgCl₂在醇中溶解和蒙脱土(MMT)在醇中层间膨胀的特性,制备了MgCl₂/TiC_l4负载于MMT层间的MMT/MgCl₂/TiC_l4催化剂,并通过原位聚合合成了聚乙烯/蒙脱土纳米复合材料.经广角X射线衍射(WAXD)和透射电子显微镜(TEM)分析表明,蒙脱土片层在乙烯聚合过程中发生了层间剥离,以单片层或几片层共存的形式无规地分散于聚乙烯基质中.与分子量相近的纯聚乙烯相比,极低的蒙脱土含量(质量分数<1%)能使复合材料的屈服强度、拉伸强度和拉伸模量有很大提高.复合材料中蒙脱土片层以纳米尺寸在聚乙烯基质中的良好分布和对聚乙烯分子链运动的限制作用是力学性能提高的主要因素.     

The investigation of intumescent flame-retarded polypropylene using poly(hexamethylene terephthalamide) as carbonization agent

A novel intumescent flame retardant, containing ammonium polyphosphate (APP), and poly(hexamethylene terephthalamide) (PA6T), was prepared for flame retarding polypropylene (PP). The flame retardation of the PP composites was characterized by limiting oxygen index (LOI). The thermal degradation of the composites was investigated by means of thermogravimetric analysis (TG) and TG coupled with Fourier transform infrared spectroscopy (TG-FTIR). The morphology of the char obtained after combustion of the composites was studied by scanning electron microscopy. It has been found the intumescent flame retardant showed good flame retardancy, with the LOI value of the PA6T/APP/PP (5/25/70) system increasing from 17.5 to 32. Meanwhile, the TG and TG-FTIR work indicated that PA6T could be effective as a carbonization agent and there was a synergistic reaction between PA6T and APP, which effectively promoted the char formation of the PP composites. Moreover, it was revealed that uniform and compact intumescent char layer was formed after combustion of the intumescent flame retarded PP composites.     

Effects of carbon nanotubes on the thermal stability and flame retardancy of intumescent flame-retarded polypropylene

Flame retardant mixtures of carbon nanotubes (CNTs) and intumescent flame retardant (IFR) were embedded in polypropylene (PP) to investigate what will happen if the additives exhibit two different flame retardation mechanisms. TEM tests showed that CNTs dispersed homogenously in PP matrix without any visible agglomeration. The effects of CNTs on thermal stability and flammability of PP were investigated by thermogravimetry (TG) and cone calorimetry tests, respectively. Results indicated that the introduction of CNTs only enhanced thermal stability of materials in a certain temperature range, but caused a severe deterioration of flame retardancy due to the interaction of the network structure and the intumescent carbonaceous char. Furthermore, conditions for an intumescent flame retardation system to behave with high efficiency were also discussed by a secondary combustion test.     

Effects of organo-clay and sodium dodecyl sulfonate intercalated layered double hydroxide on thermal and flame behaviour of intumescent flame retarded polypropylene

The thermal and flame performances of intumescent flame retarded polypropylene (PP/IFR) composites with organically modified clay or sodium dodecyl sulfonate intercalated layered double hydroxide (SDS-LDH) were studied. The organo-clay particles were partially exfoliated in the PP matrix, while intercalation and aggregation was obtained for SDS-LDH. Incorporation of SDS-LDH improved the thermal stability and flame retardancy of the intumescent flame retarded PP composite in the early stage of heating and combustion; while the effects of organo-clay came into play in the middle-later stage. Differences in degradation pathway of clay and LDH were responsible for the above phenomenon which bore important implication for the barrier mechanism. The introduction of organo-clay into PP/IFR not only increased the char residue, but also formed compact and folded morphology of char residue which provided more effective protect for underlying materials against heat and oxygen relative to LDH, thus improved the flame retardancy of intumescent flame retarded PP samples more efficiently.     

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.     

Clays basal spacings effect on fire retardancy of polymers by TG/DTA

In this study, poly (ethylene-co-butyl acrylate, EBA-30) samples containing an intumescent formulation of ammonium polyphosphate and pentaerythritol and clays of different basal spacings had their flame retardant properties evaluated by thermogravimetric analysis, differential thermal analysis, and heating microscopy. Samples without polymeric matrix were also analyzed to observe possible interactions between the clays and the intumescent formulation. Thermal Analyses revealed that the basal spacings of the clays strongly influence their synergistic effect with the intumescent formulation studied.     

Roles of organic intercalation agent with flame retardant groups in montmorillonite (MMT) in properties of polypropylene composites

Three kinds of organic intercalation agent containing flame retardant groups, melamine (MA), triphenylphonium (TPP) chloride, and tetradecyl trihexyl phosphonium (TTP) bromide were intercalated into montmorillonite (MMT) via cation exchange reactions. These modified MMTs are combined with intumescent systems and compounded with PP. The flame retardant and thermal properties of the PP composites are studied. The organic intercalation agents in the layers of MMT play important roles in the char formation and flame retardant properties of PP composites. MA shows a better performance in limiting oxygen index (LOI) value and TPP helps to increase UL‐94 properties, whereas TTP maintains or deteriorates the flame retardancy of polypropylene/intumescent flame retardant (IFR) composites. The LOI and UL‐94 properties increase firstly and then decrease as the content of MMT increases. The MA acts as a blowing agent and emits an inert gas to provide migration impetus, which results in a better intumescent structured and stronger char to endure heat erosion. Although TPP and TTP emit combustible gas that burn, especially for TTP as it has a more flammable aliphatic chain. The synergistic effect between MA‐MMT and IFR is better than that for TPP‐MMT and TTP‐MMT. Copyright © 2014 John Wiley & Sons, Ltd.     

A novel intumescent flame retardant: Synthesis and application in ABS copolymer

A novel phosphorous-nitrogen structure containing intumescent flame retardant, poly(4,4-diaminodiphenyl methane spirocyclic pentaerythritol bisphosphonate) (PDSPB) was synthesized and characterized. Thermal stability and flammability properties of ABS/PDSPB composites were investigated by thermogravimetric analysis (TGA) and cone calorimeter test, respectively. The results showed that the addition of PDSPB enhanced the thermal stability and flame retardancy of ABS significantly. The weight of residues improved greatly with the addition of PDSPB. FTIR and SEM investigations revealed that the residual chars contain polyphosphoric or phosphoric acid, which plays an important role in the process of carbonization. The intumescent chars formed from PDSPB and ABS/PDSPB composites were intact, multicellular and strong. It is confirmed that the char structure was a critical factor for flame retardancy of ABS resin.     

Synergistic effects of cerium phosphate and intumescent flame retardant on EPDM/PP composites

An intumescent flame retardant system composed of ammonium polyphosphate (APP) and pentaerythritol (PER) was used for flame retarding ethylene–propylene–diene‐modified elastomer (EPDM)/polypropylene (PP) blends. Cerium phosphate (CeP) was synthesized and the effect on flame retardancy and thermal stability of EPDM/PP composites based on intumescent flame retardant (IFR) were studied by limiting oxygen index (LOI), UL‐94, and thermogravimetic analysis (TGA), respectively. Scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR) were used to analyze the morphological structure and the component of the residue chars formed from the EPDM/PP composites, and the mechanical properties of the materials were also studied. The addition of CeP to the EPDM/PP/APP/PER composites gives better flame retardancy than that of EPDM/PP/APP/PER composites. TGA and RT‐FTIR studies indicated that an interaction occurs among APP, PER, and EPDM/PP. The incorporation of CeP improved the mechanical properties of the materials. Copyright © 2010 John Wiley & Sons, Ltd.     

Synergistic effect of boron containing substances on flame retardancy and thermal stability of clay containing intumescent polypropylene nanoclay composites

The functions of nanoclay and three different boron containing substances, zinc borate (ZnB), borophosphate (BPO₄), and boron silicon containing preceramic oligomer (BSi), were studied to improve the flame retardancy of polypropylene (PP)‐nanoclay‐intumescent system composed of ammonium polyphosphate (APP) and pentaerythritol (PER). The flame retardancy of PP composites was investigated using limiting oxygen index (LOI), UL‐94 standard, thermogravimetric analysis (TGA), and cone calorimeter. According to the results obtained, the addition of 20 wt% intumescent flame retardant (IFR) improved the flame retardancy by increasing the char formation. Addition of clay slightly increases the LOI value and reduces the maximum heat release rate (HRR). Addition of clay also increases the barrier effect due to intumescent char, especially in thin samples. Boron compounds show their highest synergistic effect at about 3 wt% loading. According to UL‐94 test and LOI test, 3 wt% ZnB containing composite shows the highest rating (V0) and BPO₄ containing sample shows the highest LOI value (26.5). Copyright © 2010 John Wiley & Sons, Ltd.     

Thermal and flame retardant properties of novel intumescent flame retardant polypropylene composites

Novel intumescent flame retardant polypropylene (PP) composites were prepared based on a char forming agent (CFA) and silica-gel microencapsulated ammonium polyphosphate (Si-MCAPP). The thermal and flame retardancy of flame retardant PP composites were investigated by limiting oxygen index, UL-94 test, cone calorimetry, thermogravimetric analysis, scanning electron micrograph, and water resistance test. The results of cone calorimetry show that the flame retardant properties of PP with 30 wt% novel intumescent flame retardants (CFA/Si-MCAPP = 1:3) improve greatly. The peak heat release rate and total heat release decrease, respectively, from 1,140.0 to 156.8 kW m^?2 and from 96.0 to 29.5 MJ m^?2. The PP composite with CFA/Si-MCAPP = 1:3 has the excellent water resistance, and it can still obtain a UL-94 V-0 rating after 168 h soaking in water.