【作者】 王醴均；

【导师】 王经武；

【作者基本信息】 郑州大学 ， 材料学， 2011， 硕士

【摘要】 高密度聚乙烯(HDPE)是一种大品种通用塑料,由于其良好的综合性能,被广泛用于生产生活的很多方面。但是由于其氧指数低,易燃,燃烧速度快且产生大量的熔滴,从而带来较大的火灾隐患,因此,对HDPE阻燃的研究显得格外重要。随着目前阻燃领域绿色环保的呼声日益高涨,传统的卤系阻燃剂被许多国家禁止使用,开发环保的无卤阻燃高密度聚乙烯具有重要意义。膨胀型阻燃剂(IFR)具有无毒,无熔滴,发烟少等优点而受到广泛关注,近年来膨胀型阻燃剂在阻燃领域的应用取得了明显的效果,特别是用于聚烯烃阻燃。但是其也存在与基体相容性差,易吸湿,往往导致聚烯烃基复合材料力学性能明显下降等问题。针对膨胀型阻燃体系存在问题,本工作先从分子设计出发,设计一种集炭源,酸源和气源于一体的大分子阻燃剂为基体,使其带上可以和HDPE反应的双键官能团,使阻燃剂能键接在HDPE大分子上,从而改善阻燃剂分子和HDPE的相容性；为了进一步增强rIFR和HDPE的界面结合,再采用硅氧烷偶联剂对rIFR进行表面改性。将rIFR与HDPE进行热机械反应性共混,在熔融挤出的过程中使rIFR和HDPE发生化学反应,形成结合力强的适度柔性界面,制备出具有良好阻燃效果且力学性能较良的HDPE基复合材料。对rIFR的合成工艺、化学结构、热稳定性和HDPE/rIFR复合材料的化学结构、形态结构、阻燃性能、力学性能、熔体流动性、阻燃机理等进行了研究。得到以下主要结果和结论：(1)磷酸和季戊四醇按照摩尔比为2.5：1,得到中间体PEDP; PEDP与三聚氰氨(MA)、丙烯酰胺改性三聚氰胺-脲醛树脂(MUF-AM)的摩尔比为1/1/1时,制备得到的反应性膨胀型阻燃剂rIFR的收率达到56.5%,残炭率为47.52%。(2) rIFR起始分解温度为220℃,其分解温度区间也覆盖了HDPE热分解温度范围,与HDPE的加工及热降解温度相匹配。(3) rIFR和HDPE基体形成了化学键连接,改善了两相的相容性。(4)随着rIFR含量的增加,HDPE/rIFR复合材料的极限氧指数LOI逐渐提高,水平燃烧速度逐渐降低,当rIFR由Owt%增加到30wt%,LOI由18.5%提高到24.5%,水平燃烧速率由33.6mm/min降低到21mm/min;对rIFR进行表面处理使复合材料的阻燃性能稍有降低,而偶联剂用量对阻燃性能影响不大。(5)随着rIFR含量的增加,HDPE/rIFR复合材料的拉伸屈服应力(TYS)基本不变,弯曲弹性模量(FM)逐渐提高,悬臂梁缺口冲击强度(NIIS)逐渐降低,当rIFR含量为30wt%时,复合材料FM提高到纯HDPE的1.40倍,TYS和NIIS分别为原料HDPE的104%,71%；采用硅氧烷偶联剂对rIFR进行表面改性后,复合材料的NIIS随着偶联剂用量的增加先增加然后基本保持不变,而TYS和FM变化不大,当偶联剂用量为rIFR的2.5wt%时,复合材料NIIS、TYS和FM分别为原料HDPE的95%,104%和140%。(6) HDPE/rIFR在燃烧时能形成膨胀型炭层,但是由于炭层不够致密牢固,导致火焰能透过炭层,引燃内层基体,使材料持续燃烧,因而阻燃性能有限。更多还原

【Abstract】 High Density Polyethylene(HDPE) has been widely used in many fields as general plastic due to its good comprehensive properties. However, there is a hidden fire trouble because it is rather flammable with low limited oxygen index (LOI), the burning is too fast and will generate a lot of melt dripping,thus it is particularly important to do research on resisting flammability of HDPE. As more and more requires of environmental protection in flame-retardant field and forbid use of conventional halogen-containing flame retardants, the research of halogen-free flame retardant HDPE is of important value.A great deal of attention has been paid to intumescent flame retardants(IFRs) due to they have advantages like no toxicity, less smoke, no melt dripping and so on. In recent years, the application of IFRs have achieved significant results in flame-retardant field, especially used in polyolefin. However, there are some disadvantantages of IFR systems, such as weak compatibility with resin, easy moisture absorption and so on.To solve the existence problems of IFR systems,this work based on molecular scale, design a macromolecular flame retatdant which is composed of three components---an acid source,a carbon source and a gas source, then make it graft p-bond which can react with HDPE, thus improving the compatibility of rIFR in HDPE matrix; In order to further enhance interfacial combination between the two phases, rIFR was surface-modified with siloxane coupling agent(KH570). Then HDPE/rIFR composites with good flame retardant properties and mechanical properties were prepared by thermol-mechanical blending. Subsequently, we studied the synthesis process,chemical structure, thermal stability of rIFR and the chemical structure,fracture morphology,flame retardant properties, mechanical properties, melt flow rate and flame retardancy mechanism of HDPE/rIFR composites. The main results and conclusions were summarized as follows:(1) We synthesized Pentaerythritol phosphate ester (PEDP) on the basis of Phosphoric acid and pentaerythritol with the mole ratio 2.5:1. Then the Reactive-type intumescent flame retardant(rIFR) was gotten with 47.52% of carbon residue and 56.5% of yield with the mole ratio of PEDP/MA/MUF-AM=1:1:1.(2) The initial decomposition temperature of rIFR was 220℃, and the decomposition temperature range of rIFR also covered the pyrolysis temperature range of HDPE, so rIFR well matched with HDPE.(3) There was chemical connection between rIFR and HDPE matrix, which improved the compatibility of two phases.(4) LOI of HDPE/rIFR composite materials increased with the content of rIFR increasing, the horizontal buring rate continuously decreased.When the content of rIFR increased from 0% to 30wt%,LOI of composites incresed from 18.5% to 24.5%, and horizontal buring rate reduced from 33.6mm/min to 21mm/min;The flame retanrdant properties of composites slightly reduced after surface treatment for rIFR,and the effect of the content of coupling agent wasn’t evident for flame-retardant properties of HDPE/rIFR.(5) The tensile yield strength(TYS) of HDPE/rIFR had no obvious viration with the content of rIFR increasing,flexural modulus(FM) of composites increased, notched izod impact strength(NIIS)of composites gradually decreased, when the content of rIFR was 30wt%,the FM got to 1.40 times that of pure HDPE, and TYS and NIIS were 104% and 71% respectively that of pure HDPE; However, after surfacial modification of rIFR by siloxane coupling agent,the NIIS of composites had maximum value which was maintained 95% that of pure HDPE when the content of coupling angent reached 2.5wt% of rIFR, and the TYS and FM got to 1.04 and 1.40 times respectively that of pure HDPE.(6) HDPE/rIFR can form intumescent carbon layer during the process of burning, however, because the char layer wasn’t thick and solid,heat and flammable volatiles could easily penetrate the char layer into the flame zone, this caused HDPE/rIFR composites had limited flame retardancy.更多还原