【作者】 宋平安；

【导师】 方征平；

【作者基本信息】 浙江大学 ， 高分子化学与物理， 2009， 博士

【摘要】 聚丙烯具有透明度高、无毒、易加工、吸湿性低、抗冲强度高、耐化学腐蚀、电绝缘性好及性价比高等优点，从而被广泛应用于化工、建筑、轻工、家电、包装等领域，在五大通用塑料中，消费量仅次于聚乙烯位于第二。但是，由于聚丙烯本身极易燃（极限氧指数仅约17．0）、发热量大，燃烧速度快及燃烧时伴随着滴落，从而限制了其在对阻燃级别要求较高行业中的应用，因此，对PP的阻燃研究就显得尤为重要。随着目前阻燃领域绿色环保的呼声日益高涨且阻燃法规日益苛刻，开发无卤阻燃聚丙烯的任务迫在眉睫。本文针对聚丙烯特殊的燃烧机理，对其开展了膨胀阻燃、纳米阻燃及其协同阻燃三大方面的研究。首先，从分子结构设计出发，采用三氯氧磷、4，4’-二氨基二苯甲烷和季戊四醇三种原料通过三步反应合成出了一种端氨基齐聚物型单组分（三源一体）膨胀型阻燃剂，聚（4，4-二氨基-二苯甲烷-O-双环季戊四醇磷酸酯-磷酸酯），缩写为PDBPP。采用红外、氢核磁及X-射线光电子能谱等手段表征了其分子结构。热重分析表明PDBPP无论在空气还是氮气中都具有良好的热稳定性及优异的膨胀成炭能力，如在空气中的600℃时的残炭高达55vt％，且与聚丙烯的加工及热解温度相匹配。随着PDBPP的加入，不仅使聚丙烯的热稳定性和极限氧指数大幅度提高，还使聚丙烯的热释放速率、总放热量及质量损失速率显著降低。当用相容剂-马来酸酐接枝聚丙烯来增容阻燃聚丙烯体系后，PDBPP在基体中的分散尺寸减小到原来的十分之一，增强了PDBPP与基体间的界面粘附力。另外，增容反应使聚丙烯的热稳定性和阻燃性能进一步提高。最为重要的是，增容反应使阻燃聚丙烯的拉伸强度维持了纯聚丙烯的拉伸强度值。其次，采用富勒烯(C₆₀)阻燃聚丙烯。在低添加量时，即≤2wt％，热重分析和锥形量热分析表明C₆₀不仅使聚丙烯的热稳定性和热氧化稳定性显著提高，与碳纳米管对聚丙烯的热稳定性提高幅度相当，而且使聚丙烯燃烧时的热释放速率、质量损失速率大幅度降低。流变行为、热处理及残炭等研究揭示C₆₀之所以可以提高聚丙烯的热稳定性和阻燃性能，是因为其可以捕捉聚丙烯降解时产生的自由基及其衍生的高活性的H·和·OH自由基，同时使得熔体的粘度急剧上升，这就使降解的小分子产物需要更多的能量和时间逃逸到上层。另一方面，动态力学测试表明C₆₀在聚丙烯中体现了纳米粒子的增强效应。第三，利用C₆₀和PDBPP为原料，合成了一种树枝状大分子纳米／膨胀协同阻燃剂，即C₆₀-d-PDBPP。采用红外、氢核磁、X-射线光电子能谱、透射电镜等手段表征了其分子结构及形貌。扫描电镜和透射电镜观察显示C₆₀-d-PDBPP比纯C₆₀更容易分散在聚丙烯中。热重分析和锥形量热分析表明前者比后者能更进一步提高聚丙烯的热稳定性，同时还使聚丙烯燃烧时的热释放速率和质量损失速率值进一步减小，延缓其燃烧过程，体现了很强的协同阻燃效应。阻燃机理研究表明C₆₀超强的捕捉自由基能力及PDBPP的高成炭能力之间存在着协同效应，从而使的聚丙烯的热稳定性和阻燃性能得到进一步改善。第四，利用C₆₀和碳纳米管为原料，通过碳纳米管的羟基化、氨基化及C₆₀功能化三步反应合成了一种纳米／纳米协同阻燃剂，即C₆₀-d-CNTs。采用红外光谱、X-射线光电子能谱、透射电镜和扫描电镜等手段表征了其分子结构及形貌。由于C₆₀-d-CNTs中含有未反应的活性氨基和羟基，因此，通过添加马来酸酐接枝聚丙烯来进行原位增容反应使其比纯C₆₀和碳纳米管任何一者都更容易分散在聚丙烯基体中。阻燃机理研究表明C₆₀的捕捉自由基能力和碳纳米管形成的网络结构所产生的屏蔽效应具有协同作用，与纯碳纳米管相比，C₆₀-d-CNTs不仅能把聚丙烯的热降解温度移向更高温度，而且使其燃烧过程变得更加缓慢，热释放速率更小，表明两者之间存在着显著的协同阻燃效应。最后，采用碳纳米管的羟基化、磷酰化及原位缩聚三步法合成了一种膨胀型阻燃剂包覆碳纳米管协同阻燃剂，即IFR-w-CNTs。采用红外光谱、X-射线光电子能谱、透射电镜和扫描电镜等手段表征了其分子结构及形貌。通过调节IFR与碳纳米管两者的投料比，可以控制IFR-w-CNTs的管径，并为透射电镜观察所证实。由于IFR-w-CNTs表面含有活性氨基和羟基等官能团，通过添加马来酸酐接枝聚丙烯来进行原位增容反应可以使其在聚丙烯基体中均匀分散。当IFR与碳纳米管之间的重量比为1：2时，不仅两者的协同阻燃效应达到最大值，而且对聚丙烯力学性能的增强效应也达到了最大值，可使聚丙烯的拉伸强度由35．1 MPa提高到40．8 MPa。更多还原

【Abstract】 Polypropylene （PP） is widely applied to various fields like chemical,construction,light industry,household appliance,and package due to its overwhelming advantagessuch as high transparency,nontoxicity,ease of processing,low hygroscopicity,highimpact-strength,resistance to chemical erosion,excellent electric insulation,and highperformance-price ratio.Currently,its consumption is only second to that ofpolyethylene among the top-five general plastics.Unfortunately,PP is ratherflammable with a limited oxygen index （LOI） value of around 17.0.In addition,itcombusts too fast and generates a great of heat accompanied by dripping,whichsignificantly limits its wide applications,thus it is of significance to reduce itsflammability.Firstly,based on the molecular design,we synthesized an amino terminatedoligomeric intumescent flame retardant,poly （4,4-diamino diphenylmethane-O-bicycli pentaerythritol phosphate-phosphate）,PDBPP for short,on thebasis of phosphrous oxychloride,pentaerythritol,and 4,4’-diaminodiphenyl methane,and the chemical structure of PDBPP was characterized by IR,¹H-NMR,and XPS.The results of thermal analysis showed that PDBPP had excellent thermal stabilityand char-forming ability,yielding 55.0 wt% char residue at 600℃in air atmosphere.Besides,it could match well the processing temperature of PP.Incorporation ofPDBPP not only resulted in a remarkable improvement in the thermal stability andLOI values,but markedly reduced the heat release rate,total heat release and massloss rate of PP.Using maleic anhydride grafted polypropylene （PP-g-MA）as thecompatibilizer,the interfacial tension was improved and the sizes of PDBPP domainsin PP matrix were significantly reduced to one tenth of those of PP/PDBPP samplesbefore compatibilization.Moreover,compatibilization led to a further improvement inthe thermal stability and flame retardancy of PP,while tensile strengths of PP/PDBPPsystems were restored to the levels similar to that of pure PP even if with a 30 wt%PDBPP loading. Secondly,we employed fullerene (C₆₀) to reduce the flammability of PP.TGA andcone calorimeter measurements displayed that at very low loading （（?）2wt%）,C₆₀could remarkably improve the thermal stability and dramatically reduce the heatrelease rate and mass loss rate,in which it could match carbon nanotubes （CNTs）.Investigations on rheological analysis,heat-treatment and char residue demonstratedthat C₆₀ could trap the free radicals created by the decomposition of PP and otherderivative free radicals like H·and·OH,which will make the melt viscositydramatically increase and consequently make the small molecules need much moreenergy and time to spread into the flame zone to support the combustion as fuels.Inthis way,C₆₀ improved the thermal stability and flame retardancy of PP.Dynamicmechanical thermal analysis （DMA） exhibited that C₆₀ had the reinforcing effect butaccompanied by the plasticization effect for PP.Thirdly,we employed C₆₀ to decorate PDBPP and fabricated a dendrimer-likemacromolecular nano/intumescence synergistic flame retardant,C₆₀-d-PDBPP,whosechemical structure and morphology were characterized by IR,XPS,TEM and SEM.C₆₀-d-PDBPP could readily disperse well in PP matrix through employing PP-g-MAas the compatibilizer since many active amino and hydroxyl groups existed inC₆₀-d-PDBPP molecule.The combination of the high free-radical-trapping ability ofC₆₀ and excellent char-forming ability of PDBPP further heightened the thermalstability and reduced the flammability of PP,evidenced by the observation of muchhigher thermal degradation temperature and much lower peak heat release rate.Subsequently,through the hydroxylation,amino-functionalization,and C₆₀-functionalization of CNTs,we synthesized a novel nano/nano synergistic flameretardant,C₆₀-d-CNTs which was characterized by IR,XPS,TEM and SEM.Compared with C₆₀ and CNTs,C₆₀-d-CNTs was much easier to disperse in PP matrixbecause its structure contained plenty of active amino and hydroxyl groups and thusthe interfacial adhesion could be improved through compatibilization reaction withPP-g-MA as the compatibilizer.Synergistic flame retardancy effects could beobserved from the further reduction in peak heat release rate of PP.Both the highfree-radical-trapping ability of C₆₀ and the barrier effect caused by the CNTs network were responsible for the elevation of thermal stability and the improvement in theflame retardancy of PP.Finally,through hydroxylation and phosphorylation of CNTs,and in-situcondensation polymerization,we fabricated an intumescent-flame-retardant wrappedCNTs,IFR-w-CNTs,which was characterized by IR,XPS,TEM and SEM.Thediameter of IFR-w-CNTs could be controlled through adjusting the feed ratio of IFRto CNTs.Due to the fact that IFR-w-CNTs contains active amino and hydroxyl groups,we employed PP-g-MA as the compatibilizer to reduce the interfacial tension betweenIFR-w-CNTs and PP,thus IFR-w-CNTs could disperse better in PP matrix relative topristine CNTs.The cone calorimeter measurements clearly indicated that,comparedwith CNTs,IFR-w-CNTs could make the peak heat release rate reduce to a greaterextent at the same loading level,which was due to the fact that the char residuecreated by the decomposition of IFR adhered onto the surface of CNTs andconsequently made the CNTs network more compact.Interestingly,when the ratio ofIFR and CNTs was 1:2,not only the optimum synergistic flame retardancy achieved,but the reinforcement effect also reached the peak value,for the tensile strength of thePP/IFR-w-CNTs sample increased up to 40.8 MPa relative to 35.1 MPa of pure PP.更多还原