【作者】 李贵勋；

【导师】 王经武；

【作者基本信息】 郑州大学 ， 材料学， 2014， 博士

【摘要】 聚丙烯（PP）具有无毒、易成型加工、耐化学腐蚀性好、综合力学性能优良及性价比高等优点，被广泛应用于化工、建筑、家电、包装、汽车等领域，是第二大品种通用塑料。但是，由于PP极限氧指数（LOI）低，本身易燃，燃烧时发热量大，燃烧速度快，并易产生熔滴，从而限制了其在一些领域的应用，因此，对其阻燃化研究就显得尤为重要。随着人们安全和环保意识的增强，在塑料阻燃领域绿色环保的要求呼声也越来越高。在已开发和应用的阻燃剂中，磷氮类膨胀型阻燃剂由于其无毒、低烟、无腐蚀性气体释放等环保性好的优点，已是阻燃剂研发的热点。但是也存在明显不足，如：与基体树脂相容性差、易吸潮析出、恶化材料的力学性能等问题。如何制备出与PP基体树脂相容性好、添加量少并易均匀分散，制得的阻燃PP既具有优异的阻燃性能、又能基本保持PP力学性能的膨胀型阻燃剂，一直是国内外环保型阻燃PP研发受到高度重视的方向。为此，构思出如下研究思路：基于PP是一种非极性结晶性，通常易于结晶的树脂，应研制出一种单分子的反应性膨胀型阻燃剂，分子上键接有可与PP反应的官能团，增强阻燃剂与PP的相容性；集酸源、炭源、气源“三源一体”，P、N、C配比尽量合适，以便于发挥酸源、炭源、气源的协效作用。将研制出的阻燃剂与PP热机械反应性共混制备出阻燃PP，对阻燃PP的组成及结构、阻燃性能、力学性能等进行表征。基于以上研究思路，开展了如下研究工作：以三氯氧磷、季戊四醇、甲基丙烯酸羟乙酯、三聚氰胺等为主要原料，合成出了键接有能与PP反应的双键官能团，集酸源、炭源、气源“三源一体”的单分子型的反应性膨胀型阻燃剂。通过红外光谱（FTIR）、核磁（1HNMR）、元素分析等对研制出的阻燃剂的化学结构进行了表征；利用热重（TG）、扫描电镜（SEM）、FTIR等对其热稳定性、成炭性及其成炭机理进行了研究。将研制出的阻燃剂与PP进行热机械反应性共混，制备出阻燃PP；对阻燃PP的化学结构、织态结构进行了表征；研究了阻燃性能、阻燃机理；研究了力学性能及阻燃剂含量对力学性能的影响；研究了热稳定性、阻燃PP成炭机理及成炭性能；对比研究了反应性膨胀型阻燃剂及非反应性膨胀型阻燃剂阻燃PP中PP的非等温结晶行为、结晶形态、结晶结构及熔融行为。为进一步提高研制出的阻燃PP的阻燃性能及优化力学性能，研究了不同协效剂对反应性膨胀型阻燃剂阻燃PP的协效阻燃效果，对协效体系的阻燃性能、力学性能及协效阻燃机理等进行了研究。通过以上研究，取得了如下主要结果和结论：1.采取两步法合成出的“三源一体”的膨胀型阻燃剂是：3-(甲基丙烯酸乙酯)-9-((4,6-二氨基-1,3,5-三嗪)氨基)-3,9-二氧代-2,4,8,10-四氧杂-3,9-二磷杂螺[5.5]十一烷磷酸酯（EADP），其P、N、C配比为1.00:1.68:2.84，键接有可与PP反应的双键官能团；EADP在空气气氛中5%热失重温度为270.5℃，具有适宜阻燃PP成型加工的良好的热稳定性；在空气气氛中700℃时残炭率为53.66%，EADP残炭表面完整致密，炭层内形成不同大小的囊泡结构。2.制备出的阻燃PP（PP/EADP）由PP、PP与EADP的接枝共聚物、EADP的自聚物、未反应的EADP组成。如EADP含量为30wt%的PP/EADP-30，其中的EADP有29.08%键接在PP大分子上；PP/EADP具有优良的阻燃性能：如EADP含量为25wt%的PP/EADP-25，LOI为32.5%，垂直燃烧达到UL-94V-0级；热释放速率峰值(PHRR)、释热总量(THR)、平均有效燃烧热(av-EHC)分别为212.61kW/m2、90.38MJ/m2、39.47MJ/kg，比原料PP的分别降低了65.50%、20.18%、19.51%；同时EADP的加入也降低了阻燃PP的生烟性、烟释放总量；600℃残炭量为11.82%，形成表面致密、内部形成了多孔的膨胀炭层结构；PP/EADP燃烧时酸源、炭源、气源“三源”协同发生化学变化，迅速结炭和释放出NH3、H2O等不燃性气体，突显出凝聚相和气相两种阻燃机理的协同作用；PP/EADP的耐水性相当好，如PP/EADP-30，在70℃水中浸泡168h后，LOI为31.5%，通过UL-94V-0级测试；PP/EADP的热稳定性比较好。如PP/EADP-25，5%热失重温度为286℃，最大热失重速率为5.95%/min，比原料PP的下降了59.05%，完全能满足成型加工对热稳定性的要求；PP/EADP呈现出综合优良的力学性能。如PP/EADP-25，与原料PP相比，弯曲强度、弯曲模量、拉伸强度分别提高了18%、38%、8%，悬臂梁缺口冲击强度下降了7%；与原料PP相比，PP/EADP中PP的非等温结晶的起始温度、结晶峰温及结晶度明显提高，如PP/EADP-30，结晶起始温度、结晶峰温及结晶度比原料PP的分别提高了7.73℃、9.00℃和9.70%，比一般的非反应性膨胀型阻燃剂制得的阻燃PP（PP/MAPP-30）中PP的还分别提高了4.86℃、4.57℃及1.72%。EADP含量对PP/EADP中PP的非等温结晶行为有明显的影响：综合来看，PP/EADP-25中PP的结晶速率及结晶度最大；与原料PP相比，PP/EADP中PP的晶体细化，随着EADP含量增加，细化程度加大。PP/EADP中的PP是α晶型和β晶型共存的结晶结构；与原料PP相比，PP/EADP中PP的熔融起始温度、熔融终了温度稍有降低，熔融峰顶温度稍有提高。3.几种协效剂相比，加入埃洛石纳米管（HNT）制得的阻燃PP（PP/EADP/HNT=75/24/1）协效阻燃效果最好：与PP/EADP-25相比，LOI由32.5%提高到35.5%；释热速率、释热总量、有效燃烧热、比消光面积及释烟总量等分别有所降低；600℃残炭量由11.82%提高到13.53%，结炭形貌基本相同；垂直燃烧通过UL-94V-0级测试；与PP/EADP-25中PP的相比，PP/EADP/HNT（75/24/1）中PP的非等温结晶起始温度、结晶峰温基本相同，结晶度较小；结晶熔融起始温度、熔融峰温较低。PP/EADP/HNT（75/24/1）的悬臂梁缺口冲击强度与原料PP的基本相同，弯曲强度、弯曲模量、拉伸强度分别比原料PP的提高了26%、64%、11%，综合力学性能比PP/EADP-25的有所改善。几种协效剂制得的协效阻燃PP的阻燃机理与PP/EADP的基本相同：凝聚相与气相阻燃机理协同作用；几种协效阻燃PP中的PP均是α晶型和β晶型共存的结晶结构，β晶型的比例比PP/EADP中PP的稍有增加。结晶细化的情况与PP/EADP的基本相同；加入弹性体的阻燃PP（PP/E/EADP）与不加弹性体的PP/EADP相比，LOI等燃烧性能稍有降低，静态力学性能稍有降低，悬臂梁缺口冲击强度稍有提高。更多还原

【Abstract】 Polypropylene (PP) as the second largest common plastic is widely used in manyfields, such as chemical industry, building, household appliances, packaging,automobiles, etc., because of its non-toxicity, easy processing, good chemicalresistance, excellent mechanical properties and low cost advantage. However, it iseasily flammable, generates a lot of heat and produces droplet during burning due toits low limiting oxygen index (LOI) value which is the fatal shortcoming restrictingits wider application. Therefore, it is particularly important to improve the flameretardancy of PP. With the increasing consciousness of safety and environment, theenvironmental protection has been paid more and more attention. Phosphorus-nitrogen intumescent flame retardants (IFRs) have gradually been focused on due toits advantages, such as low smoke, non-toxicity and no corrosive gas release duringburning. However, IFRs have still some shortcomings, such as poor compatibilitywith matrix resins, moisture sensitivity and deterioration of material mechanicalproperties, and so on. How to prepare a kind of IFRs bearing good compatibilitywith PP, showing excellent flame retardancy and maintaining mechanical propertiesof PP, has become an important subject in the research of environmental friendlyflame retardants. The basic design principle is described as following:Due to non-polar crystalline resin of PP, we should synthesize the reactiveintumescent flame retardant not only having a functional group reacting with PP toimprove the compability, but also bearing acid source, blowing agent and charforming agent within one single molecule, together with a suitable ratio ofphosphorus, nitrogen and carbon for good synergistic effect of acid source, blowingsource and char forming agent. Then, the flame retardant PP would be achievedthrough reactive blending and its chemical structure, flame retardant properties,mechanical properties would be improved.Based on the above design principle, this work includes: A reactive intumescentflame retardant with a double bond is synthesized from phosphorus oxychloride, pentaerythritol, hydroxyethyl methacrylate and melamine. Its chemical structure ischaracterized by FTIR,1H-NMR and elementary analysis. The thermal stability andchar morphological structure are investigated by TG, SEM and FTIR. Then, flameretardant PP composites are prepared through reactive blending. The chemicalstructures of flame retardant PP composites are characterized. Flame retardancy,flame retardant mechanism, mechanical properties, thermal behaviors and charformation mechanism are investigated in detail. The non-isothermal crystallization,melting behaviors and crystalline morphology are analyzed.In order to further improve the flame retardancy and to optimize the mechanicalproperties of flame retardant PP composites, several synergists are added into flameretardant PP. The synergistic effects, synergistic mechanism and mechanicalproperties are investigated.The main research results are listed as following:1. A reactive intumescent halogen-free flame retardant bearing acid source,blowing agent and char forming agent within one single molecule,2-((9-((4,6-diamino-1,3,5-triazin-2-yl)amino)-3,9-dioxido-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5] undecan-3-yl)oxy)ethyl methacrylate (EADP), is synthesized through two-stepreaction with a certain ratio of phosphorus, nitrogen and carbon (1.00:1.68:2.84).The temperature at5%weight loss of EADP is270.5oC, indicating enough thermalstability under the molding process of polypropylene. The char yield of EADP ismeasured to be53.66%at700oC. The char takes on a compact surface and a cellularinner structure.2. PP/EADP composites are composed of PP, graft copolymer of EADP and PP,EADP homopolymer and unreacted EADP. For example, EADP is reacted in aconversion ratio of29.08%with PP in PP/EADP-30with the addition of30wt%EADP.PP/EADP composites show excellent flame retardancy. When the addition ofEADP is25wt%, the LOI value of PP/EADP-25is32.5%, passing the UL-94V-0rating. The peak heat release rate (PHRR), total heat release (THR) and averageeffective heat of combustion (av-EHC) are212.61kW/m2,90.38MJ/m2and39.47MJ/kg, which are decreased about65.50%,20.18%,19.51%compared with those of PP, respectively. Moreover, the addition of EADP decreases the smokeemission. The char yield of PP/EADP-25is measured to be11.82%at600oC. Thechar has a compact surface and a porous inner structure.While PP/EADP composites are heated and burned, the acid source, blowingagent and char forming agent react with each other generating a swollen porous charand releasing nonflammable gas such as NH3, H2O, indicating the condensed-phaseand gas-phase flame retardancy synergistic mechanisms for PP/EADP composites.PP/EADP composites have outstanding water resistance. For example,PP/EADP-30could still obtain a LOI value of31.5%and a UL-94V-0rating afterbeing soaked in70oC water for168h.The temperature at5%weight loss and the maximum weight loss rate ofPP/EADP-25are respectively measured as286oC and5.95%/min, which affordsenough thermal stability to meet the molding process.PP/EADP composites show comprehensive excellent mechanical properties.Compared with PP, the flexural strength, flexural modulus and tensile strength ofPP/EADP-25are respectively increased about18%,38%,8%except that the Izodnotched impact strength is decreased about7%.The crystallization onset temperature, the crystallization peak temperature and thedegree of crystallization of PP/EADP composites are higher than those of PP. ForPP/EADP-30composite, the crystallization onset temperature, the crystallizationpeak temperature and the degree of crystallinity are respectively increased about7.73oC,9.00oC and9.70%compared with those of PP and about4.86oC,4.57oC and1.72%compared with those of non-reactive intumescent flame retardant PP(PP/MAPP-30). One of them, the rate of crystallization and the degree ofcrystallinity of PP/EADP-25are the biggest.Compared with neat PP, the crystal size of PP/EADP composites is obviouslysmall. With the increasing content of EADP, PP crystal size turns smaller. PP inPP/EADP composites exhibits α-form and β-form crystal structures.Compared with neat PP, the melting onset temperature and melting endtemperature of PP/EADP composite are slightly decreased and the melting peaktemperature is increased a little. 3. Halloysite nanotubes (HNT) are the most effective synergistic agent. Comparedwith PP/EADP-25, the LOI value of PP/EADP-HNT(PP/EADP/HNT=75/24/1)composite with1wt%addition of HNT is increased from32.5%to35.5%with theheat release rate, total heat release, effective heat of combustion, specific extinctionarea and total smoke release decreased. The char yield of PP/EADP-HNT isincreased from11.82%to13.53%at600oC, passing the UL-94V-0rating.Compared with PP/EADP-25, the crystallization onset temperature andcrystallization peak temperature of PP/EADP-HNT composite are the almost sameas those of PP/EADP-25. Besides, the degree of crystallinity, the melting onsettemperature and the melting end temperature of PP/EADP-HNT composite aresmaller than those of PP/EADP-25.Compared with neat PP, the flexural strength, flexural modulus and tensilestrength of PP/EADP-25are increased about26%,64%,11%, respectively. The Izodnotched impact strength is the same as that of PP.The flame retardant mechanism of synergistic flame retardant PP is similar toPP/EADP composites.All the synergistic flame retardant PP composites show the coexistence of α-formand β-form crystal structures while the content of β-form crystal is higher than thatof PP/EADP-25. The crystal size of PP/EADP-HNT composite is close to that ofPP/EADP-25.With the addition of elastomers into flame retardant PP, the flame retardantparameters and static mechanical properties are slightly decreased and the Izodnotched impact strength is improved.更多还原