【作者】 叶磊；

【导师】 瞿保钧；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2010， 博士

【摘要】 随着人们环保意识和火灾安全意识的日益增强,无卤阻燃剂金属氢氧化物,如氢氧化镁(MH),和磷氮类膨胀型阻燃剂正受到越来越多的重视。然而MH基无卤阻燃聚烯烃材料的阻燃效率低、填充量大、抗热变形能力差；膨胀型阻燃剂同样存在抗热变形能力差、燃烧时容易滴落、与卤素阻燃剂相比较阻燃效率较低等缺点,这也严重影响了这两类阻燃剂的应用。因此如何提高MH和磷氮类膨胀型阻燃聚烯烃材料的力学、阻燃、加工以及热性能是目前亟待解决的难题。本文采用无机纳米增效和紫外光交联方法来改善无卤阻燃聚烯烃材料的结构,以提高无卤阻燃聚烯烃材料的性能来克服以上的缺点,并取得了一些重要的进展,其主要的贡献有：1.研究了层状双氢氧化物(LDH)与超细氢氧化镁(HFMH)、微胶囊化红磷(MRP)以及膨胀石墨(EG)在LDPE/EVA/LDH纳米复合材料中的协同阻燃和力学增强作用。XRD(X射线衍射)和TEM(透射电镜)测试表明LDH可以作为相容剂使体系中的HFMH分散的更为均匀。力学性能、阻燃性能和TGA数据表明层离的LDH可以起到阻燃协效剂和纳米增强剂的作用,提高材料的阻燃性能、力学强度和热性能。2.利用离子交换法制得了磷酸根插层的LDH(也称水滑石),通过XRD、FTIR(傅立叶红外光谱)、CCT(锥形量热器)、TGA(热重分析)、LOI(氧指数)和UL-94(垂直燃烧)测试研究比较了磷酸根插层水滑石和碳酸根插层水滑石在EVA复合体系中的阻燃特性和热降解行为。研究表明在相同的水滑石的添加量下,EVA/MgAl-PO4复合材料比普通的EVA/MgAl-CO3具有更好的阻燃性能和热性能。3.研究了MWNTs(多壁碳纳米管)和MH在EVA/MH/MWNT纳米复合材料中协同阻燃作用及其机理。CCT、LOI以及TGA测试表明,加入一定量的MWNTs可以提高EVA/MH材料的阻燃性能和热性能。扭矩测试、形貌变化测试和炭层的SEM测试结果表明MWNTs在EVA基体中形成网络结构提高了材料熔融态时的粘度,同时在燃烧时覆盖在了聚合物表面并帮助形成更致密的炭层。4.通过FTIT,CCT, SEM, TGA, LOI和UL-94等测试研究了纳米气相二氧化硅与膨胀型阻燃剂NP在PP/NP体系中的协同阻燃作用。结果表明,适量的纳米气相二氧化硅可以提高材料的阻燃性能和热稳定性。主要是由于在PP/NP/SiO2体系中SiO2可以帮助形成了更为结实致密的炭层所致,但是过量的纳米气相二氧化硅则会破坏膨胀炭层使之无法起到有效的隔热隔氧的作用,降低了材料的阻燃性。5.研究了膨胀型阻燃LLDPE/EVA/NP复合材料在添加了适量的光引发剂和交联剂的情况下的紫外光交联和相关性能。凝胶含量和热延伸测试结果显示该复合材料可以轻易地通过紫外光进行交联。CCT、LOI、TGA和动态FTIR测试表明光交联的LLDPE/EVA/NP样品比未交联的样品具有更好的阻燃性能和热稳定性,同时光交联样品的力学强度和耐水性也得到了大大的提高。更多还原

【Abstract】 Metal hydroxides and intumescent flame retardant additives have been extensively used in halogen-free flame retardant (HFFR) polymeric materials. However, main disadvantages of HFFR additives are low FR efficiency and large additive amount to deteriorate mechanical properties and not to resist high temperature, which are hard to meet the requirements of some special applications. In this thesis, we focus on improving the mechanical and thermal properties of HFFR composites via nano-synergists and photocrosslinking. The novel results are as follows:1. The synergistic effects of exfoliated layered double hydroxides (LDH) with some halogen-free flame retardant (HFFR) additives, such as hyperfine magnesium hydroxide (HFMH), microencapsulated red phosphorus (MRP), and expandable graphite (EG) in the LDPE/EVA/LDH nanocomposites have been studied. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) images demonstrate that the exfoliated LDH layers can act as synergistic compatilizer and dispersant to make the HFMH particles dispersed homogeneously in the LDPE matrix. The results from the mechanical, flame retardant and thermal analysis (TGA) tests show that the exfoliated LDH layers can also act as the nano-enhanced and flame retardant synergistic agents and increase the tensile strength, flame retardant and thermal properties of the nanocomposites.2. The flammability characteristics and flame retardant mechanism of phosphate-intercalated hydrotalcite (MgAl-PO4) in the halogen-free flame retardant EVA blends have been studied by XRD, Fourier transfer infrared (FTIR) spectroscopy, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI) and UL-94 tests.. The obtained results show that the hydrotalcite intercalated by phosphate possesses the enhanced thermal stability and flame retardant properties compared with ordinary carbonate intercalated hydrotalcite MgAl-CO3 in the EVA blends.3. The synergistic effects and mechanism of multiwalled carbon nanotubes (MWNTs) with MH in halogen-free flame retardant EVA/MH/MWNTs nanocomposites have been studied by CCT, LOI, TGA, torque test, morphologic evolution experiment, and SEM. The data obtained from the CCT, LOI, and TGA show that suitable amount of MWNTs have synergistic effects with MH in the EVA/MH/MWNTs nanocomposites. The experimental observations from the torque, morphologic evolution tests, and SEM give positive evidences that network structure formation of MWNTs in the EVA/MH matrix increased melt viscosity of the nanocomposites and promoted the formation of compact charred layers during burning or thermal degradation.4. The synergistic effects of fumed silica on the thermal and flame retardant properties of PP/IFR based on the NP phosphorus-nitrogen compound have been studied by FTIR, CCT, SEM, TGA, LOI and UL-94 tests. The CCT, LOI and UL-94 data show that when≤1 wt% fumed silica substituted for the NP can increase the flame retardant and thermal stability of the PP/IFR/SiO2 blends. The The dynamic FTIR spectra and morphological structures of charred residues observed by SEM give the positive evidence that the suitable amount of fumed silica can promote the formation of compact intumescent charred layers and prevent the charred layers from cracking, which effectively protect the underlying polymer from burning. However, a high loading of fumed silica deteriorates the flame retardant and thermal properties of the PP/IFR blends.5. The photoinitiated crosslinking of halogen-free flame retarded LLDPE/EVA blends with the IFR of NP in the presence of photoinitiator and crosslinker and their characterization of related properties have been investigated. The data from the gel content and heat extension rate (HER) show that the LLDPE/EVA/IFR/NP blends can readily crosslinked by UV-irradiation under suitable amount of photoinitiator and crosslinker. The data obtained from the CCT, LOI and the dynamic FTIR spectra indicate that photocrosslinking can apparently increase the flame retardant and thermal properties of the LLDPE/EVA/NP samples. The data from the mechanical tests and water-resistant measurements show that photocrosslinking can considerably improve the mechanical and water-resistant properties of LLDPE/EVA/NP samples.更多还原