【作者】 张文超；

【导师】 杨荣杰；

【作者基本信息】 北京理工大学 ， 材料学， 2013， 博士

【摘要】 中国阻燃工业在过去30年中获得快速发展，研究人员对于阻燃剂、阻燃材料和阻燃机理等方向的研究越来越深入和全面，并在国际相关领域扮演着更加重要和关键的角色。目前，随着人类对于环境保护和自身健康问题的关注，关于高效、廉价、成熟的含卤阻燃剂的应用遇到了无法解决的问题。因此，无卤阻燃剂的开发和应用目前已经成为了世界阻燃领域关注的焦点。本论文的选题是将9,10-二氢-9-氧杂-10-膦菲-10-氧杂（DOPO）和笼型低聚硅倍半氧烷（POSS）结合用于阻燃环氧树脂，以发挥磷、硅两种阻燃元素的协同作用。研究焦点包括：首先合成了一种新型无卤阻燃剂DOPO-POSS，并从DOPO-POSS阻燃环氧树脂所表现出的吹熄阻燃效应开始，对吹熄阻燃环氧树脂机理进行了详细研究，吹熄阻燃环氧树脂效应是环氧树脂在燃烧过程中快速形成炭层，在很短的时间内，开始有热解气体从炭层内部高速喷出，并熄灭残留火焰的现象。本文的研究为无卤阻燃环氧树脂的研究开辟了一个崭新的方向。（一）本论文以9,10-二氢-9-氧杂-10-膦菲-10-氧杂（DOPO）和VTES（乙烯基三乙氧基硅烷）为原料，通过两步法成功合成了含有DOPO基团的笼型低聚硅倍半氧烷DOPO-POSS。该物质及其合成方法已经获得专利授权。将DOPO-POSS作为一种新型阻燃剂应用于阻燃环氧树脂时发现了吹熄阻燃效应，基于这种吹熄效应，硅、磷阻燃元素的阻燃效率可以显著提高。为了对吹熄阻燃环氧树脂机理进行详细研究，作者将所在实验室合成的八苯基笼型低聚硅倍半氧烷（OPS）、八氨苯基笼型低聚硅倍半氧烷（OAPS）、梯型聚苯基硅倍半氧烷（PPSQ）等硅倍半氧烷系列阻燃剂单独或与DOPO复配用于阻燃环氧树脂。研究发现，虽然OAPS可以与环氧树脂单体进行反应，但它与非反应型的OPS相比，并没有表现出特殊的阻燃性质，它们与DOPO复合使用都可以使该种环氧树脂出现吹熄阻燃效应，相比较而言，OPS具有更高的阻燃效率，更有益于吹熄阻燃效应的发生。笼型的OPS和OAPS都可以使环氧树脂出现吹熄阻燃效应，但是含有梯型PPSQ的环氧树脂中却没有吹熄现象发生。这是因为由PPSQ所引起的交联结构和成炭的过程不能与环氧树脂本身的炭层膨胀过程相匹配，所以导致其炭层多为破裂炭层。这样的炭层不能聚集热解气体，所以该体系中没有吹熄效应出现。而由OPS引起的交联结构和成炭的过程却与EP炭层的膨胀过程很好的匹配，该结果说明，只有当炭层强度与热分解气体释放速率相匹配时，才能发挥最好的吹熄阻燃效果。（二）本论文研究所涉及的环氧树脂单体包括双酚A二缩水甘油醚（DGEBA）和四缩水甘油基-4,4’-二氨基二苯甲烷（TGDDM），所涉及的固化剂包括芳香族固化剂4,4-二氨基二苯基砜（DDS）、间苯二胺（m-PDA）和脂肪族固化剂低分子量聚酰胺（PA650）。在DGEBA/m-PDA、DGEBA/DDS、TGDDM/DDS环氧树脂体系中发现了吹熄阻燃效应，而DGEBA/PA650体系中，吹熄效应却始终没有出现。这说明环氧树脂单体和固化剂的结构对吹熄阻燃效应有很大影响。通过对比DGEBA/DDS和DGEBA/PA650两种环氧树脂的交联网络结构与吹熄阻燃效应的关系，发现含有较多芳香链段的环氧树脂体系更有利于形成吹熄阻燃效应。因为在这样的环氧体系中，更容易快速形成高强度的交联炭层，这一炭层可以聚集热分解气体并最终形成吹熄效应。在TGDDM/DDS环氧树脂中，发现了最为典型的吹熄阻燃效应。DOPO-POSS和OPS/DOPO都可以使该环氧树脂表现出突出的吹熄阻燃效应，并使该环氧树脂体系获得优异的阻燃效果。UL-94垂直燃烧结果显示它们都可以使该环氧树脂达到UL-94V-0级。OPS/DOPO阻燃的TGDDM/DDS环氧树脂在凝聚相中出现了蜂窝状膨胀炭层，而且炭层中含有大尺寸空腔，这样的结构使OPS/DOPO阻燃的TGDDM/DDS环氧树脂表现出了更强的吹熄阻燃效应。（三）本论文采用热重分析-傅里叶红联用（TGA-FTIR）、热重分析-质谱联用（TGA-MS）、X射线光电子能谱仪（XPS）、X射线衍射仪（XRD）、扫描电镜（SEM）、热重分析仪（TGA）、示差扫描量热仪（DSC）、傅里叶红外光谱仪（FTIR）、应力流变仪等测试手段对阻燃材料及其燃烧产物（气相和凝聚相）进行定性或定量分析。采用锥型量热法（cone calorimeter）、极限氧指数法（LOI）和垂直燃烧法（UL-94）等方法对阻燃材料进行阻燃性能和燃烧过程进行分析研究。除了采用以上常规测试手段和实验方法外，为了研究吹熄阻燃效应的阻燃机理，作者在本文第5章中采用了自己设计的两种实验方法对吹熄阻燃环氧树脂效应进行了研究。第一种方法是对环氧树脂在锥形量热测试燃烧过程中不同时间和不同位置的炭层进行了取样和研究，通过分析这些炭层样品，我们基本掌握了纯环氧树脂及阻燃环氧树脂在燃烧过程中外部、内部和底部炭层的化学结构变化和阻燃元素含量变化情况。第二种方法是将热电偶固化在环氧树脂中，该方法使我们掌握了普通环氧树脂和吹熄阻燃环氧树脂在UL-94垂直燃烧过程中的凝聚相温度的变化情况。这两种实验方法为吹熄阻燃机理的研究提供了不可或缺的数据和材料，文中所采用的测试手段及实验方法详见各章实验部分。（四）本论文中所涉及的吹熄阻燃环氧树脂机理研究包括：（1）采用自己设计的实验方法对纯环氧树脂（EP）及阻燃环氧树脂在燃烧过程中外部、内部和底部炭层的化学结构变化进行分析，证明燃烧是由于样品表面链段断裂释放的可燃挥发物被点燃造成的。随后，EP内部的基质开始分解并不断向外表面补充可燃性挥发物来维持燃烧，同时，外部炭层中开始发生交联反应。此时，如果炭层能够聚集热解气体，则可促使吹熄阻燃效应的发生。而如果不能形成有效炭层，随着EP基材热降解反应的加速，更多的可燃性挥发物将会迁移到表面，在此时样品将达到轰燃状态。FTIR，XPS等分析结果显示，DOPO与POSS共同使用可以在凝聚相中生成-P(=O)-O-Si-结构，该结构可以作为连接桥将三维Si(-O)4网络与稠环芳烃相连接，促使燃烧区域快速形成有效炭层结构。在垂直燃烧过程中，此炭层在点燃过程中就可以快速形成，聚集内部的热分解气体，并最终促使吹熄阻燃效应形成。（2）通过SEM、应力流变仪、视频分析等手段以及对环氧树脂样品燃烧过程的凝聚相产物进行分析，发现具有吹熄阻燃效应的环氧样品燃烧时都可以快速形成有效炭层，并且炭层中存在大尺寸的空腔，这种空腔将有助于聚集热分解气体。当空腔中充满热分解气体时，整个空腔可以作为气体隔层来阻碍热量的传播。当气压达到一定程度并可以冲破炭层时的时候，吹熄阻燃效应将会发生。（3）采用将热电偶植入环氧树脂的实验方法对环氧树脂燃烧过程中的凝聚相温度进行研究，研究发现吹熄效应可以有效减缓热量向未分解聚合物基材的传播速度，同时还能通过喷射而出的气流将热源火焰带走，这种隔热作用延长了环氧树脂在较低温度下的分解时间，这是吹熄效应的形成的关键因素。（4）通过TGA-FTIR、TGA、XPS等手段对不同温度条件下环氧树脂的凝聚相及气相分解产物进行分析。研究发现环氧树脂在较低的温度下分解将会有更多的残炭生成，这将有助于气相产物的聚集。同时气相产物分析结果显示，环氧树脂在较低的温度下分解正好可以使气相分解产物具有较高的CO2浓度，这意味着吹熄效应发生时喷射而出的气体具有较低的可燃性，因而更易熄灭样品残余火焰。（5）通过综合考虑吹熄阻燃效应的影响因素和机理分析结果，作者在本论文中建立了吹熄阻燃效应的物理模型。该模型显示，吹熄阻燃机理明显区别于气相阻燃机理、凝聚相阻燃机理、膨胀阻燃机理等传统的阻燃机理。（五）本论文研究中，吹熄阻燃效应显著提高了硅、磷元素对环氧树脂的阻燃效率，使阻燃剂添加量大幅下降。其中硅、磷阻燃元素总添加量约为0.5wt%时获得UL-94V-0级（1.6mm和3.2mm）阻燃配方3个，获得UL-94V-1级（3.2mm）阻燃配方5个；硅、磷阻燃元素总添加量约为0.9wt%时获得UL-94V-0级（3.2mm）阻燃配方1个。较低的阻燃剂添加量意味着在同等阻燃条件下，环氧树脂的综合性能将会明显提高，吹熄阻燃环氧树脂体系具有巨大的潜在应用价值。更多还原

【Abstract】 In China, the flame retardant industry experienced rapid development over thepast30years. Research about flame retardant, flame retardant materials and flameretardant mechanism is more and more in-depth and comprehensive, and plays a moreimportant role in the related fields of international. At present, as the human attentionon environmental protection and the human health problems, the research andapplication about mature halogen-contained flame retardant seems to have problemswhich are difficult to solve. Therefore, development and application of halogen freeflame retardant has became the focus of the flame retardant field.The topic of my paper is using9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and polyhedraloligomeric silsesquioxanes (POSS) to flame retard epoxy resins (EP), the phosphorusand silicon are expected to play a synergy effect. Polyhedral oligomericsilsesquioxanes of the caged structures with the DOPO groups (DOPO-POSS) weresynthesized. The blowing-out effect was detected in epoxy resins flame retarded byDOPO-POSS, and the flame retardant mechanism of blowing-out of epoxy resin havebeen studied in detail. The “blowing-out effect” is that:“after the sample was ignited,it showed an unstable flame for several seconds; with the pyrolytic gaseous productsjetting outward from the condensed-phase surface, the flame was extinguished, itlooks like that the gas blew out the flame”. This study has opened up a new directionfor the research of halogen-free flame retardant epoxy resin.1. The DOPO-POSS were synthesized by two-step method using DOPO andvinyl triethoxy silane (VTES). The DOPO-POSS and its synthesis method hasobtained patent license. The DOPO-POSS was used as novel flame retardant to flameretard epoxy resins and the blowing-out effect was detected in this system. Based onthe blowing-out, the flame retardant efficiency of phosphorus and silicon wasimproved obviously. In order to understand the flame retardant mechanism ofblowing-out effect, octaphenyl POSS (OPS), octaaminophenyl POSS (OAPS) andpolyphenylsilsesquioxane (PPSQ), which are synthesized in our lab, are used alone orcompanied with DOPO to flame retard EPs. The studies show that although OAPS can react with epoxy monomer, it hassimilar flame retardant action compared with unreactive OPS. The OPS and OAPScompanied with DOPO could make epoxy resins shows remarkable blowing-outeffect. Comparing OPS and OAPS, the OPS is more effective and helpful to theformation of blowing-out effect. However, the epoxy resins with ladder-type PPSQcannot occur the blowing-out effect. This result is caused by that the cross-linking andcharring in the condensed phase caused by PPSQ cannot match the intumescent andcharring process of the EPs during combustion. Therefore, such a solid char may bevery brittle, and may crack very easily. This char layer cannot accumulate thepyrolytic gases to form the blowing-out effect. On the contrary, cross-linking in thecondensed phase caused by OPS seems to have the desired retarding effect. Theseresults indicate that only when the release speed of pyrolytic gases and the condensedphase structures match each other, the blowing-out out effect can show the bestperformance.2. The epoxy monomers in this paper are diglycidyl ether of bisphenol A(DGEBA) and tetraglycidyl-4,4’-methylene dianiline (TGDDM), the curing agents arethe aromatic4,4’-diaminodiphenylsulfone (DDS), m-phenylenediamine (m-PDA) andthe aliphatic oligomeric polyamide650(PA650). In this research, the blowing-outeffect can be detected in the DGEBA/m-PDA resins, DGEBA/DDS resins andTGDDM/DDS resins, however, the blowing-out effect did not show up in theDGEBA/PA650resins. This result indicates that the structures of epoxy resinsmonomer and curing agents are very important for the blowing-out effect. Throughanalysis the relationship between curing structures and blowing-out effect in theDGEBA/DDS resins and DGEBA/PA650resins, we find that the more aromaticstructures in the curing net is helpful to the blowing-out effect. This is because themore aromatic structures are easy to form crosslinked char layer, which couldaccumulate the pyrolytic gases easily and enable the formation of blowing-out effect.In the TGDDM/DDS resins, the typical blowing-out effect can be detected. TheDOPO-POSS and OPS/DOPO are used to flame retard the TGDDM/DDS resins. Theblowing-out effect can be detected during the UL-94tests of them. The UL-94resultsindicate that DOPO-POSS or OPS/DOPO could make the UL-94test of TGDDM/DDS resins reach V-0rating. The morphology of the char layer ofTGDDM/DDS flame retarded by OPS/DOPO is like a honeycomb, and severalindividual cavities can be detected under this char layer. This kind of char layer makesthe OPS/DOPO system showed more intensive blowing-out effect than theDOPO-POSS system.3. Thermal gravimetric analyzer was coupled with Fourier transform infraredspectrometry (TGA-FTIR), thermal gravimetric analyzer was coupled with massspectrometry (TGA-MS), x-ray photoelectron spectroscopy (XPS), x-raydiffractometer (XRD), scanning electron microscopy (SEM), thermal gravimetricanalyzer (TGA), differential scanning calorimetry (DSC), fourier transform infraredspectrometry (FTIR), and stress rheometer are used to qualitative or quantitativeanalysis of the flame retardant materials and its combustion products (gas phase andthe condensed phase). The cone calorimeter analysis, limited oxygen index andUL-94vertical burning test are used to investigate the flame retardant property andcombustion process of epoxy resin materials. In addition to the above routineexperimental method, in order to study the flame retardant mechanism of blowing-out,two kinds of effective experimental methods were built by myself to study theblowing-out effect in epoxy resin. The first method is that during the combustionprocess of cone calorimeter test of epoxy resins, the condensed phase samples ofdifferent time and the condensed phase samples of different position are investigated.Based on this method, we find the changes of chemical structures and element contentin the external, internal and bottom residues. The second method is that athermocouple which was used to identify the temperature of condensed phase wasembedded in the EPs. This method enabled us to grasp the temperature data in thecondensed phase during the UL-94vertical burning test of pure epoxy resin and theepoxy resin with blowing-out effect. These two kinds of experimental methodsprovide essential data and materials for the research of flame retardant mechanism ofblowing-out effect. The detail of all experimental methods can be found in everychapter.4. In this paper, the research about flame retardant mechanism of blowing-outeffect includes that: (1) An experimental method was set up to investigate the condensed phasesamples of different time and the condensed phase samples of different positionduring the combustion process of cone calorimeter test of epoxy resins. These resultsindicate that the ignition of EP is caused by flammable volatile fragments due to thescission of the EP chain in surface. Then, the internal degradation and combustiblegas release would outward supply the fuel to support the flame, and the C elementbegins to increase due to fast crosslinking reaction. At this point, if the char layer cangather pyrolysis gas, blowing-out effect can happen. And if sample can’t formeffective char layer, with the acceleration of thermal degradation reaction of EPmatrix, more combustible volatiles will migrate to the surface, the samples will reachflashover state. The char residues were investigated in detail by FTIR and XPS. Theinteractions between DOPO and silsesquioxane in the condensed phase are caused bythe formation of the-P(=O)-O-Si-structure. The-P(=O)-O-Si-structure is helpful toaccelerate the formation of effective char layer. During the vertical burning tests, thiskind of char layer could accumulate the pyrolytic gases easily and enable theformation of blowing-out effect.(2) The SEM, stress rheometer, video analysis were used to investigate thecondensed phase product created during the combustion process, we found that thequick formation of effective char layer can be observed in every blowing-out flameretardant system. Furthermore, the big cavities can be detected under this char layer,which is helpful to accumulate the pyrolytic gases. This kind of cavities with pyrolyticgases (gasbags) will become a thermal insulation layer, which is effective to inhibitthe heat transfer from the fire to the unburned polymer matrix. With the increase ofgas pressure in the cavities, the char layer would be broken, then, the blowing-outeffect would present.(3) In addition, to measure the internal temperature profiles in the ignited end ofsamples in UL-94tests, a thermocouple was embedded in the epoxy resins. Thisexperiment indicates that the blowing-out effect can slow the heat transfer from thefire to the unburned matrix, and also take away part of the heat in the surface zone bythe spurting gases. This heat insulation effect prolongs the decomposition of theunburned EP matrix at low temperature. This is the key factor for the formation of blowing-out effect.(4) The TGA-FTIR, TGA, XPS were used to analyse the condensed phaseproducts and gas phase products of different temperature. These results indicate thatthe low temperature decomposition results in more char formation during combustionwhich is helpful to the accumulation of pyrolytic gases. The gas phase analysisindicates that the low temperature decomposition results in a high proportion of CO2in the pyrolytic gases, which means the jetting gas are lower flammable gaseousproducts. This kind of jetting gases can extinguish the remnant fire easily.(5) Depending on the summarization of the impact factors and experimentalanalysis of blowing-out effect, a physical model of blowing-out effect was establishedin this paper. According to this physical model, the flame retardant mechanism ofblowing-out effect is quite different with the traditional mechanism that gas phaseflame retardant mechanism, condensed phase flame retardant mechanism, andintumescent flame retardant mechanism et al.5. This paper, the blowing-out effect improve the flame retardant efficiency ofsilicon and phosphorus elements for epoxy resins, and reduce the content of flameretardants obviously. When content of silicon and phosphorus element is about0.5wt%, four EP materials with UL-94V-0rate (1.6mm and3.2mm) and four EPmaterials with UL-94V-1rate (3.2mm) were obtained. When content of silicon andphosphorus element is about0.9wt%, one EP material with UL-94V-0rate (3.2mm)was obtained. The lower content of flame retardants means lower damage of theoriginal properties of epoxy resin materials. So epoxy resin materials flame retardedby blowing-out effect possesses huge potential application value.更多还原