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为了获得满足工程需要的高性能的硅泡沫材料,本文针对混合发泡法和溶析成孔法制备的硅泡沫材料开展了电镜扫描、单轴压缩和应力松弛实验,通过对材料微观结构特征和宏观力学性能的以及实验数据分散性的对比,对材料的综合性能进行了全面评估。研究表明,材料的应力松弛及力学性能主要受泡孔结构的影响。相对于混合发泡法制备的混合泡孔的硅泡沫材料,溶析成孔法制备的球形泡孔的硅泡沫材料具有优异的压缩性能和较低的应力松弛率,且实验数据重复性更好。而采用无规共聚或多嵌段共聚合成技术能够进一步改善材料的压缩和松弛性能。 相似文献
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为了给60 Coγ辐照条件下硅泡沫垫层的构型设计和工艺优化提供依据,本工作通过材料辐照实验、力学实验和扫描电子显微镜观察等方法,研究了60 Coγ射线辐照对硅泡沫材料压缩性能的影响,探索了辐照条件下硅泡沫材料的损伤机理,并在此基础上建立了辐照环境条件下多孔硅泡沫材料压缩性能的预测模型,给出了材料压缩模量和断裂应变随辐照剂量的变化规律.结果表明:γ辐照对材料压缩性能的影响较为明显,在预压缩量较低的情况下,辐照后硅泡沫材料力学性能呈先升后降的趋势;当预压缩量超过50%时,辐照后硅泡沫材料力学性能呈先陡后缓的下降趋势.预压缩量为30%、辐照剂量为300 kGy时,硅泡沫材料的拉伸强度和剪切强度分别增加了69%和84%;而辐照剂量增大到1000 kGy时,其值分别下降了47%和50%.结合材料宏观性能和细观结构的分析认为,γ辐照引起的交联反应和降解反应是造成硅泡沫材料力学性能改变的主要原因. 相似文献
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通过甲基乙烯基硅氮烷与聚硅氮烷共热聚反应,将乙烯基引入先驱体聚硅氦烷,分析了甲基乙烯基硅氦烷与降硅氮烷的结构。讨论了两者共热聚的反应过程,找到了适宜的制备方法。制得了几种不同乙烯基含量的聚硅氦烷,并经熔融纺丝制得的含乙烯基的聚硅氦烷纤维。 相似文献
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由于泡沫夹芯型结构复合材料具有轻质、宽频、高效、兼容等优点,是雷达吸波材料的理想选择。新型聚甲基丙烯酰亚胺泡沫因具有良好的力学性能、热变形温度和化学稳定性,受到高性能夹层结构复合材料领域的广泛关注。为了使聚甲基丙烯酰亚胺(PMI)泡沫具有吸波功能,在制备PMI泡沫的过程中需要加入吸波剂,但是吸波剂通常密度较大、易沉淀。若没有在制备方法中使用防沉淀技术或均匀分散技术,吸波剂在聚合过程中会出现严重沉降,吸波剂难以发挥最大功效,且泡沫原有的力学性能降低严重。因此,文中通过对聚甲基丙烯酰亚胺吸波泡沫制备工艺的改进,系统研究了增黏剂、交联剂及吸波剂含量对泡沫结构与性能的影响,通过二氧化硅增黏工艺,使吸波剂在泡沫中分散均匀,成功制备了力学性能及吸波性能优异的吸波泡沫,高温压缩强度到达0.7 MPa以上,并且可在2~18 GHz实现全频吸收,获得了具有结构/隐身一体化宽频聚甲基丙烯酰亚胺吸波泡沫的制备方法。 相似文献
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几种高分子材料的核辐射效应研究 总被引:7,自引:0,他引:7
对氟聚合物、硅橡胶泡沫和环氧树脂等材料在核辐射作用下的物理化学行为及其力学性能变化进行了研究。本研究所得主要实验数据和结论均未见文献报导。 相似文献
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Guodong Huang Guomei Chen Guangfei Li 《Fullerenes, Nanotubes and Carbon Nanostructures》2016,24(11):698-704
Graphene oxide/ultra-high-molecular-weight polyethylene (GO/UHMWPE) nanocomposite has a potential application for artificial joints. However, free radicals and antioxidative properties of irradiated GO/UHMWPE were not clearly clarified. In this paper, GO/UHMWPE nanocomposites were prepared and irradiated by gamma-irradiation with a dose of 100 kGy. Afterward, test samples were aged in air. Free radicals and molecular structures of test samples were investigated by electron spin resonance (ESR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy, respectively. These studies indicated that irradiation enhanced GO radical concentrations. And GO radicals were stable in air and even could not be quenched after accelerated aging. GO radicals were superimposed on free radicals of irradiated UHMWPE. Although GO showed free radical-scavenging capacity, the influence of GO on free radicals of irradiated UHMWPE was too weak to be observed in ESR spectroscopy. Free radicals concentrations of irradiated GO/UHMWPE nanocomposites were gradually decayed with aging time evolving in air. Observing the oxidation index values of test samples, it was proposed that irradiated GO/UHMWPE might show very weak antioxidative properties. 相似文献
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Single walled carbon nanotues (SWCNTs) of high purity and multi walled carbon nanotubes (MWCNTs) were radiated by high energies of proton and electron beams. The surface physical properties were examined by XRD and TEM for both irradiated and non-radiated samples to compare the effect of radiation. The possible changes of surface characteristics were investigated by isotherm gas adsorption technique using Ar which can probe the local structure in an order of atomic scale. A series of Ar gas adsorption results measured below 77 K revealed significant changes in surface properties of carbon nanotubes by the bombardment of proton beams, which may induce the local surface defects. It is speculated that reactions on carbon nanotubes radiated by beams were led by kinetic energy transfer of the bombardments. 相似文献
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在室温空气气氛中用电子束(EB)辐照拉伸取向后的聚醚醚酮(PEEK)片,研究了辐射对取向性PEEK片材性能的影响。采用X射线衍射(XRD)、热重分析(TGA)、差示扫描量热(DSC)和万能拉力机等手段测试了不同辐射吸收剂量对取向性PEEK片受力方向(平行方向)和垂直于受力方向(垂直方向)的结晶性能、热稳定性、力学性能和热收缩性能的影响。结果表明,在实验吸收剂量范围内,样品的结晶温度、熔融焓以及结晶度都随着吸收剂量的增加而减小;随着吸收剂量的增加样品的热稳定性降低;在空气气氛中辐照样品,其平行和垂直方向上的断裂伸长率、断裂应力均随吸收剂量的增加而减小;辐照后样品平行方向的热收缩率是垂直方向的2倍,在不同吸收剂量的条件下两方向的热收缩率都不变。 相似文献
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D. Fink M. Müller P. Szimkowiak M. Döbeli A. Spieler M. Grether 《Fullerenes, Nanotubes and Carbon Nanostructures》2013,21(6):911-962
Abstract Thin fullerite films - partly covered with a thin Au layer -have been irradiated with 100 keV Arn+ (n = 1, 6, and 12), 250 keV N+, and 30 keV Au+ ions up to high fluences, and subsequently analyzed by profilometry, Rutherford Backscattering Spectrometry (RBS), and Atomic Force Microscopy (AFM). Depending on the system, either an increase or a decrease of the film thickness after the irradiations was found, and the probing RBS α particles suffered sometimes an enhanced, and sometimes a reduced energy loss upon passage through the films. The comparison of profilometry and RBS results on uncovered and covered samples allows us to separate the different effects which influence the behavior of high-fluence irradiated fullerite samples clearly from each other. Such effects might be the incorporation of the projectile ions, density changes, phase changes, sputtering, and transport of neighbored unirradiated matter into the irradiated zone. It is remarkable that ion irradiation of fullerite can lead as well to a densified material, with densities of about 2.1 g-cm?3, as to a foam-like carbonaceous material with a density around 0.35 g-cm?3 - depending on the type of projectile and its range. The latter case appears to be characteristic for high-fluence heavy noble gas implantation into fullerite. Fullerite sputtering was reconfirmed to decrease inversely with the fluence. 相似文献
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研究辐照导致硼硅酸盐玻璃机械性能的影响, 对高放废物的长期安全处置具有重要的意义。本工作采用0.3 MeV的P离子、4 MeV的Kr离子、5 MeV的Xe离子以及8 MeV的Au离子分别辐照硼硅酸盐玻璃, 利用纳米压痕技术表征了辐照前后样品的硬度和模量。结果表明: 硼硅酸盐玻璃的硬度和模量在一定范围内会随着辐照剂量的增大而减小, 辐照达到0.1 dpa时硬度和模量变化趋于饱和, 此时硬度下降了35%, 模量下降了18%; 而且不同种类的离子辐照对硼硅酸盐玻璃的硬度和模量造成的变化趋势基本相同。使用掠入射X射线衍射仪对样品晶态结构进行了分析, 发现辐照后硼硅酸盐玻璃仍保持非晶状态。利用Raman光谱对辐照后样品的微观结构的变化进行了表征, 发现辐照会导致玻璃网络结构发生改变, 玻璃的聚合度下降, 无序度增加。本工作还证明了离子辐照导致玻璃机械性能变化的主要因素是离子在样品中的核能量沉积导致玻璃结构的改变。 相似文献
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为了提高聚丁二酸丁二醇酯(PBS)基复合材料的性能,降低生产成本,采用熔融共混法制备了麦秸粉/PBS-聚己二酸-对苯二甲酸丁二醇共聚酯(PBAT)复合材料,利用60Co-γ射线对该复合材料进行了辐射改性。研究了辐射改性对麦秸粉/PBS-PBAT复合材料力学性能、热稳定性和热变形温度的影响,并采用FTIR和SEM表征了复合材料的结构和断面形貌。结果表明:当三烯丙基异氰脲酸酯(TAIC)的含量为1wt%时,复合材料经30 kGy剂量辐射后,其拉伸强度、弯曲强度和冲击强度分别提高了20%、23.5%和6.5%;辐射改性提高了复合材料的高温分解速率,使其热变形温度上升了约11℃,并增强了复合材料组分间的粘结性。 相似文献
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本文对用聚乙烯作为潜在的廉价的光接收体以测量抵达地面的太阳紫外辐射进行了研究。发现含特定添加剂的厚度0.2mm的聚乙烯片可用来连续累积测定波长范围300~400hm的太阳与天空紫外光的辐照量,按照光电法仪器的订定,投射到聚乙烯片曝露表面的太阳与天空紫外光的辐照量是归属为由聚乙烯的光降解导致生成的末端乙烯基的909cm~(-1)红外吸收峰的吸光度增量的幂函数。同时聚乙烯的光降解亦与其他气候因素有关,但它们的影响可以通过由曝露期间的平均气温建立的经验式予以修正,用本法在广州进行的全年连续监测结果表明,它的测量值与以光电转换为工作原理的仪器之测量值比较,偏差小于10%。 相似文献
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氨基树脂型膨胀阻燃剂处理软质聚氨酯泡沫塑料的阻燃性能 总被引:2,自引:0,他引:2
首先合成了两种氨基树脂型膨胀阻燃剂(简称FR)并应用于软质聚氨酯泡沫塑料(简称SPUF),所得阻燃SPUF采用热重分析、锥形量热仪研究其热解、阻燃性能,并用Kissinger方程计算SPUF的动力学参数热解活化能的变化,结果发现,阻燃SPUF的热量释放、烟气、CO和CO2排放大大降低,剩炭率增加,添加质量分数30%的阻燃剂可使材料氧指数(LOI)达27左右,有较好的阻燃效果,并根据其对力学性能的影响选出了适宜的SPUF阻燃剂。阻燃SPUF热解活化能降低~50 kJ/mol,表明阻燃剂对SPUF的热解具有催化成炭作用。 相似文献