【作者】 刘杰；

【导师】 顾嫒娟；

【作者基本信息】 苏州大学 ， 材料学， 2009， 硕士

【摘要】 人工介质材料是脉冲多普勒(PD)雷达罩的关键夹层材料,其应具有轻质、耐热、介电常数可调、力学性能优良的特点。为适应高性能PD雷达罩的发展,高性能人工介质材料的研发具有重要意义。人工介质材料主要由树脂基体和功能性填料组成,属于一类复合材料。由于树脂基体不仅是复合材料的基本组成,而且是决定材料性能(如耐热性、介电性能、工艺性、层间剪切强度等)的关键因素,因此高性能人工介质材料的研制必须以高性能树脂为基体。氰酸酯树脂(CE)树脂是含有两个或两个以上氰酸酯官能团(-OCN)的衍生物,它具有优异的介电性能,特别在较宽的温度(0-220℃)和频率(0-1011Hz)范围内具有非常低且稳定的ε和tanδ值,还具有高耐热性、低吸湿率、粘接性佳、加工性好等,因此被认为是“二十一世纪制备高性能的结构/功能材料最具有竞争力的树脂品种”,在航空航天、电子信息、交通运输等尖端工业领域显示出巨大的应用潜力。本文首次提出基于CE树脂研制新型高性能人工介质材料的新思路,设计与制备了CE基二元复合材料和三元复合材料,首次深入探讨影响CE基二元复合材料(金红石/CE、空心玻璃微珠/CE)和三元复合材料(金红石/空心玻璃微珠/CE)结构与性能的主要影响因素,初步阐明了CE基人工介质材料结构与性能之间的规律,为获得新型高性能人工介质材料提供新的理论和实际依据。本文的研究内容尚未见诸报道。对于金红石/CE复合材料,探讨了金红石的表面性质与含量对CE固化反应性及其机械物理性能的影响。研究结果表明,金红石的表面性质对CE固化反应有显著影响。经过硅烷偶联剂KH550和钛酸酯偶联剂NDZ-401处理的金红石(分别记为Rutile(KH550)和Rutile(NDZ-401))因表面带有活性基团,可以有效低地加速CE的凝胶。另一方面,金红石的存在也增加了固化反应活化能,使得凝胶后CE固化需要更大的活化能,但所有复合材料与CE具有相同的反应级数。复合材料的介电常数可以通过控制Rutile(KH550)的含量在2.95-8.81之间调节。当Rutile(KH550)含量低于40wt%时,可以采用Lichteneker方程对介电常数进行预测。Rutile(KH550)的含量对复合材料的介电损耗也有显著的影响,当Rutile(KH550)含量低于30wt%时,复合材料的介电损耗低于CE树脂的介电损耗值,随着Rutile(KH550)含量的增至40 wt%时,复合材料的介电损耗趋于稳定。而后趋于稳定。此外,Rutile(KH550)有助于提高材料的热稳定性。对于空心玻璃微珠/CE复合材料,重点探讨了空心玻璃微珠的表面性质与含量对CE基复合材料的密度、静态力学性能、动态力学性能、热性能和介电性能的影响。研究结果表明,不论空心玻璃微珠的表面性质如何,它们均可降低CE树脂的ε、tanδ和CTE,但是影响幅度不同。HGB(KH550)的加入对降低材料CTE的作用更为显著,而HGB对降低材料的ε和tanδ值略微更显优势。HGB(KH550)能够有效地降低材料的密度和吸水率。4wt%HGB(KH550)可以略微提高材料的初始分解温度,随着HGB(KH550)含量的增加,复合材料的最大分解速率峰温度与CE树脂的相应值相比,变化不大,但实际残留率较理论残留率高。对于Rutile(KH550)/HGB(KH550)/CE复合材料,重点研究了材料组成的配比对复合材料的密度、介电性能、热膨胀系数及动态力学性能的影响。研究结果表明,Rutile(KH550)/HGB(KH550)/CE复合材料的ε和tanδ值均低于CE树脂的相应值,并可根据Rutile(KH550)和HGB(KH550)与CE的配比进行有效调节。当填料与树脂的质量比为1:3时,通过调节Rutile(KH550)和HGB(KH550)的质量比在0.2:1 ~ 1:0.2之间变化,则复合材料的密度介于0.68~1.17g/cm3,tanδ介于0.004~0.010,ε介于2.90~3.74。Rutile(KH550)/HGB(KH550)/CE复合材料的CTE值明显低于CE树脂的相应值。Rutile(KH550)/HGB(KH550)/CE复合材料的动态损耗峰均呈现为一个主峰加一个小肩峰的形状,主峰与肩峰所对应的Tg值几乎不随着组成配比而变化。更多还原

【Abstract】 Manual dielectrics are key materials for Pulse Doppler (PD) radar redome, which should have low density, good thermal resistance, adjustable dielectric constant and high mechanical properties. It is important to develop high performance manual dielectrics to meet the requirements for advanced PD redoes. In general, manual dielectrics are composites made up of organic matrix and functional fillers. It is known that the matrix is not only the basic component of a composite, but also the key factor for determining the main properties of the composites such as thermal resistance, dielectric property, processing characteristics and interfacial shear strength, so high performance matrices must be employed to develop advanced manual dielectrics.Cyanate esters (CEs) are derivatives of compounds containing two or more cyanate (-OCN) functional groups, which have excellent dielectric properties, especially low and stable dielectric constant and dielectric loss over a wide range of temperature (0-220℃) and frequency. (0-1011Hz), outstanding thermal and moisture resistance, good adhesion as well as good processing characteristics, so CE resins have been considered as“the most competitive resins for developing structural/functional materials in 21st century”, showing great potential in many fields including aviation and aerospace, electric and transportation.In this thesis, the new idea of developing high performance manual dielectrics based on CE resins is proposed in the first time, binary composites and ternary composites were designed and prepared. The main factors which have influences on structure and properties of these composites were intensively discussed, and the structure-property relationship was primly developed to supply new theoretic and technological bases. No similar investigations have been found in the literatures.For Rutile/CE composites, the effects of the surface nature and content of rutile on the curing behavior and physical/mechanical properties were discussed. Results show that the surface nature of rutile has significant influences on the curing behavior of CE. The rutiles treated by the coupling agent, KH550 or NDZ-401, coded as Rutile(KH5500) or Rutile (NDZ-401), respectively, have active groups, so they can effectively catalyst the gelation of CE. On the other hand, the presence of rutiles also increases the activation energy of the curing reaction, so the resultant system requires greater activation energy for curing after gelation. In addition, CE and all composites have the same reaction order. The dielectric constant of compostes can be adjusted between 2.95 and 8.81 by controlling Rutile(KH550) content. When Rutile(KH550) content is not bigger than 40wt%, the Lichteneker equation can be used to predict the dielectric constant of the composites. Rutile(KH550) content also has obvious effect on the dielectric loss of composites. When Rutile(KH550) content is less than 30wt%, the dielectric loss of the composite is lower than that of CE resin; when Rutile(KH550) content increases to 40wt%, the dielectric loss of composites tends to have stable value. At last the addition of Rutile(KH550) into CE resin is beneifical to improve the thermal stability.For hollow glass beads/CE composites, the effects of the surface nature and content of hollow glass beads on the density, statistic and dynamic mechanical properties, thermal and dielectric properties were mainly discussed. Results show that no matter what their nature is, hollow glass beads can decrease dielectric constant (ε), dielectric loss (tanδ)and thermal expansion coefficient (CTE). HGB(KH550) has bigger influence on decreasing the density, water-absorption of composites than HGB, while HGB tends to have slightly bigger ability to decrease both values ofεand tanδ. HGB(KH550) can effectively decrease the density and water-absorption of materials. 4wt%HGB(KH550) slightly increases the initial decomposition temperature; with continuous increase of HGB(KH550) content, the temperature for the maximum decomposition rate of composites is similar as that of CE resin, but the char yields of composites are greater than the theoretical dataFor Rutile(KH550)/HGB(KH550)/CE composites, the effect of the formulations of composites on the density, dielectric properties, thermal expansion coefficient and the dynamic mechanical properties of the composites were emphasized investigated. Results show that bothεand tanδvalues as well as CTE of Rutile(KH550)/HGB(KH550)/CE composites are lower than those of CE resin, and can be effectively adjusted by controlling the formulations of composites.. When the weight ratio of fillers and resin is 1:3, by varying the weight ratio of Rutile(KH550) and HGB(KH550) from 0.2:1 to 1:0.2, then the density, tanδorεof composites change between 0.68 and 1.17g/cm3, 0.004-0.010 or 2.90-3.74, respectively. The damping factor peaks of all Rutile(KH550)/HGB(KH550)/CE composites are made up of a main peak plus a small shoulder, their corresponding Tg values almost do not change with the formulation of the composites.更多还原