PI/介孔氧化硅复合材料的制备与性能研究

通过四乙氧基硅烷的水解、缩合制备八(四甲基铵)倍半硅氧烷(TMA-POSS),以TMA-POSS为硅源,十六烷基三甲基溴化铵(CTAB)为模板荆,制备了六方有序纳米介孔氧化硅.采用原位聚合法制备了聚酰亚胺(PI)/介孔氧化硅复合材料,并讨论了介孔氧化硅的含量对PI材料的介电常数和热稳定性的影响.结果表明,加入介孔氧化硅有利于降低PI的介电常数和提高热稳定性,当其质量分数为5%时,PL/介孔氧化硅复合材料的介电常数可降至2.69.     

石墨烯/Fe3O4/FeSiAl复合材料的制备及吸波性能

以FeSiAl片状磁粉、膨胀石墨为主要原料,采用水热法制备石墨烯/Fe_3O_4/FeSiAl复合材料。通过XRD、SEM、Raman、FTIR和矢量网络分析仪(VNA)对石墨烯/Fe_3O_4/FeSiAl复合材料的晶相、微观形貌和吸波性能进行了表征和分析。结果表明:通过水热还原法,将氧化石墨烯还原成石墨烯,并且生成的石墨烯及Fe_3O_4颗粒均匀包覆在FeSiAl片状磁粉上,这种片状和颗粒状不同结构的复合,制备出了兼具磁损耗和介电损耗的吸波材料。在0.2~2.66 GHz频段内,当氧化石墨烯和FeSiAl质量比为1∶9,相应匹配厚度为2 mm时,石墨烯/Fe_3O_4/FeSiAl复合材料在2.56 GHz处最小反射率可达到–17 dB,其有效吸收频带范围(反射率小于–10 dB)为2.27~2.66 GHz。随着氧化石墨烯与FeSiAl质量比的增加,石墨烯/Fe_3O_4/FeSiAl复合材料的有效吸收频带向高频移动,有助于该吸波材料在高频段的应用。     

复配改性黏土/丁腈橡胶纳米复合材料的结构及性能

用不同阴离子表面活性剂十二烷基磺酸钠(SDS)和十二烷基苯磺酸钠(SDBS)与阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)复配改性无机黏土,制备了有机改性黏土/丁腈橡胶(NBR)纳米复合材料,并表征了有机黏土与纳米复合材料,考察了不同表面活性剂及配比对纳米复合材料物理机械性能的影响。结果表明,CTAB/SDS复配改性黏土/NBR纳米复合材料的层间距比CTAB改性黏土/NBR纳米复合材料增加了1.15 nm,具有更多的插层结构,橡胶基体中黏土颗粒分布细致、均匀,且黏土片层间无聚集体存在;CTAB/SDS复配改性黏土/NBR纳米复合材料的物理机械性能优于CTAB/SDBS复配改性黏土/NBR纳米复合材料及CTAB改性黏土/NBR纳米复合材料,且当CTAB/SDS(质量比)为4∶2时,纳米复合材料的拉伸强度、撕裂强度及扯断伸长率出现最大值,其中,拉伸强度和撕裂强度较CTAB改性黏土/NBR纳米复合材料分别提高了62.7%和12.3%。     

基于表面改性纳米硅复合负极材料的制备及其性能EI北大核心CSCD

基于简单易操作的湿法包覆制备了以纳米硅粉体和石墨(G)为主要原料,添加表面活性剂脂肪醇聚氧乙烯醚和石墨烯(GR)的Si/C@GR/G复合材料。研究了不同组分配比对复合材料的成分、形貌及电化学性能的影响。结果表明:制得的复合材料具有良好的循环稳定性,体积膨胀得到缓解。当复合材料中硅质量分数为10%,首次放电比容量约为730 mA·h/g,在电流密度为100 mA/g经100次循环后,其放电比容量稳定维持在500 mA·h/g左右,也展现了良好的倍率性能,首次Coulombic效率达到87.27%,相比纯硅不足70%的效率有了大幅度提高。     

WSiOx介孔分子筛的合成与表征

以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)作为模板剂,正硅酸乙酯(TEOS)作为硅源,在强碱性条件下,加入过渡金属氧化物偏钨酸铵合成得到WSiOx介孔分子筛,使用乙酰丙酮作为助剂,考察其对孔结构的影响,通过X射线衍射仪(XRD)、N2吸附-脱附、原位红外(FT-IR)、扫描电镜(SEM)表征手段对合成出的WSiOx上分子筛的结构性能进行研究.随着W质量分数的增加,介孔特征衍射峰的有序度增加,质量分数大于6%后有序度下降;W的加入没有破坏介孔分子筛的骨架结构.最后的结果得到,最佳W质量分数为5%,模板剂质量分数为1.8%,乙酰丙酮质量分数为9%.平均孔径为4.68 nm,比表面积为966 m2/g.     

聚氧乙烯醚型非离子表面活性剂的乳化性能的比较研究

以环氧乙烷加成数接近9的烷基醇聚氧乙烯醚为研究对象,比较性研究了壬基环己醇聚氧乙烯醚(9)、壬基酚聚氧乙烯醚(10)、异构十三醇聚氧乙烯醚(9)、仲醇聚氧乙烯醚(9)以及十二醇聚氧乙烯醚(9)五种非离子表面活性剂对几种日用化学品用油及其混合物的乳化力。实验结果表明,支链化疏水基更有利于非离子表面活性剂对油的乳化,壬基环己醇聚氧乙烯醚(9)具备替代壬基酚聚氧乙烯醚(10)在日用化学品中应用的潜力。     

硅油/水纳米乳液的制备技术研究

以聚二甲基硅油为油相物质,非离子表面活性剂为乳化剂,采用相转变温度(PIT)法制备了硅油/水纳米乳液。通过研究硅油/乳化剂/水体系的拟三元相图,确定了纳米乳液的原料配比,并对优化配方体系制得的硅油/水纳米乳液样品进行表征。结果表明,在配方组成(w/%)为:脂肪醇聚氧乙烯醚乳化剂5,聚二甲基硅油5,余量为水的条件下,制备的纳米乳液的乳化粒子粒径在165 nm左右,其Zeta电位为-0.95 mV,乳化粒子呈球形。     

萜烯基Bola型表面活性剂的合成及性能研究

以歧化松香为原料,经重结晶提纯得到脱氢枞酸,通过磺化和成盐两步反应,高收率合成得到Bola型萜烯基二钠盐阴离子表面活性剂(STDS)。采用FT-IR对STDS进行结构表征,并考察STDS与阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)的复配性能。结果表明,STDS与CTAB具有协同复配增效作用,在质量分数比例为1∶1时,复配增效作用最强,复配体系具有优异的乳化、润湿和泡沫性能,其中乳化能力由8S提高到197S,表明萜烯基Bola型STDS表面活性剂具有同CTAB复配使用作为乳化剂的巨大应用潜力。     

胶原基有机硅表面活性剂的性能研究

合成了胶原基有机硅表面活性剂(CBES),并研究了CBES的表面张力、临界胶束浓度、HLB值、乳化性能以及与非离子表面活性剂异构十三醇聚氧乙烯醚复配后的表面活性和乳化性能。通过吊片法测得CBES可使水的表面张力降低至30.5 mN/m,临界胶束浓度为0.44 g/L;采用乳化法测定CBES的HLB值为14~15,表明CBES为水溶性表面活性剂。此外,CBES乳化大豆油、氨基硅油和聚醚硅油的乳化率分别为10.5%,48.7%和90.0%,且与异构十三醇聚氧乙烯醚复配在乳化效力上具有协同增效作用。     

聚偏二氟乙烯/炭黑复合膜的制备与介电性能

添加高介电陶瓷粒子来提高复合材料的介电常数常因高含量陶瓷粒子影响复合材料的力学性能。本文将炭黑粒子引入到聚偏二氟乙烯(PVDF)中来降低陶瓷粒子的用量,通过固相混合法将PVDF和炭黑粒子混合后热压制备两相高介电复合材料。利用傅立叶红外光谱、X射线衍射、差示扫描量热仪、热重分析、动态力学分析仪和宽频介电谱阻抗分析仪等手段对复合材料的结构和性能进行分析发现。炭黑粒子均匀地分散在PVDF基体中,并存在一定的化学键作用。复合材料的力学性能随着炭黑粒子的升高而降低很小,当炭黑含量为3%时,介电常数最高达到19。     

聚四氟乙烯胶乳与碳黑粒子共凝聚行为的研究

提出了用共凝聚的方法制备填充聚四氟乙烯(PTFE)的思想,以Al(NO3)3、CaCl2、KCI为凝聚剂进行PTFE分散乳液与碳黑粒子的共凝聚。考察了胶乳种类、凝聚温度、搅拌转速等对共凝聚过程的影响规律,初步探讨了共凝聚粒子的成粒机理。结果表明共凝聚粒子是疏水性的,粒子内碳黑分散均匀。     

介质阻挡放电协同复合碳材料去除VOCs

挥发性有机物（VOCs）是常见的空气污染物,实验研究低温等离子体催化技术去除以甲苯为代表的VOCs。采用炭粉末、酚醛树脂和致孔有机高分子聚合物的有机溶剂混合物作为前驱物,经过炭化、水汽活化和负载锰催化剂,制备一种基于发泡金属的复合碳材料。采用扫描电子显微镜、XRD、全自动比表面积及微孔孔隙分析仪对材料进行表征。两段式介质阻挡放电反应器结合复合碳材料降解甲苯,前段介质阻挡放电初步降解甲苯,后段复合碳材料利用介质阻挡放电产生的长寿命活性物种和臭氧进一步去除甲苯。输入电压为10 kV时,甲苯去除率约99.4％,CO₂选择性达72.2%,并且有效控制了副产物臭氧。实验结果表明,复合碳材料有望应用于如臭氧和VOCs等的污染控制。     

Microwave Properties of TATB Particles from Measurements of the Effective Permittivity of TATB Powders

Complex permittivity is the constitutive property required to fully define the absorption, reflection, and transmission of microwave frequency electromagnetic energy for a non‐magnetic material. We report the complex permittivity of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) powder from 1 to 18 GHz. The average complex permittivity of individual TATB particles was estimated from measurements of the complex permittivity of the powder at two different densities. TATB was found to have low permittivity, low dielectric loss with nearly constant valued permittivity between 1 and 18 GHz. These data are used to calculate the complex permittivity of a composite composed of TATB and Kel‐F 800.     

聚氨酯掺杂铜粉涂层的电磁特征及其涂层织物的吸波性能

将掺杂了不同含量微米铜粉的聚氨酯（PU）涂料通过涂层工艺涂敷在棉织物上制成吸波涂层织物,并利用扫描电子显微镜、红外光谱和矢量网络分析仪等测试了不同铜粉含量聚氨酯涂层的介电常数、磁导率和电磁损耗等电磁性能,同时还探讨不同铜粉含量涂料对涂层织物电磁吸收性能的影响。结果表明,在 8~13 GHz 的频段范围内,随着涂层中铜粉含量增加,涂层介电常数实部与虚部均增大,铜粉具有良好的介电性能,在外加电场的作用下产生极化,对电磁波产生介电损耗;铜粉不属于磁损耗材料,对电磁波产生磁损耗较小;当铜粉的含量较低（3 %,质量分数,下同）时,涂层材料的吸波与电磁屏蔽性能较弱,当含量由5 %增加至11 %时,在9.0、10.5、12.8 GHz处反射损耗最低分别为-20.4、-28.3、-25.6 dB,有效吸收带宽分别为0.2、1.3、1.1 GHz,电磁屏蔽效能分别由12.24、16.59、21.1 dB增加至25.92 dB。     

Ti3C2Tx/Ni/TiO2复合粉体的制备及吸波性能研究

采用热处理的方法制备出二维层状Ti3C2Tx/Ni/TiO2复合粉体,并利用TG-DSC、SEM、XRD和XPS对样品进行表征分析,通过矢量网络分析仪测试样品的电磁参数并模拟计算不同涂层厚度下样品的反射损耗值(RL).结果表明:随着热处理温度的升高,样品中TiO2质量含量增加;当热处理温度为300℃时,在频率f=17....     

Novel high dielectric constant and low loss PTFE/CNT composites

Spherical Ca_0.55Nd_0.3TiO₃ ceramic filled polytetrafluoroethylene composites (abbreviated as PTFE/CNT) with different filler volume fractions were prepared. The effects of filler volume fraction on microstructure, dielectric properties and thermal property were studied by scanning electron microscope, vector network analyzer and thermal dilatometer, respectively. The SEM results show that spherical particles are advantageous to reduce the porosity in the interphase which would increase the dielectric loss. Moreover, both the dielectric constant and dielectric loss increased with the increasing volume fraction of CNT microspheres. The high dielectric constant and low dielectric loss composite can be prepared when the ceramic volume fraction is 50?V%: ε_r =?12, tan?δ?=?8.5?×?10^?4 (at 10?GHz). Different models were used to predict the dielectric constant of composite, and the effective medium theory shows the least deviation from the experiment. The experimental coefficient of thermal expansions of composites with different volume fractions were less than theoretical data due to the change from loosely bound polymer chain to tightly bound polymer chain which would restrain the coefficient of thermal expansions of composites.     

B4C-C复合粉体的合成及其在低碳镁碳砖中的应用

以炭黑和硼酸为原料,采用碳热还原法合成了部分石墨化B4C-C复合粉体,并将其作为碳源和抗氧化剂用于低碳镁碳砖中. 研究了加热温度对B4C-C复合粉体合成的影响,分析了其物相结构、成分、形貌和粒度. 通过测定低碳镁碳砖的常规物理性能、抗氧化性和热震稳定性,考察了复合粉体对低碳镁碳砖性能的影响. 结果表明,随加热温度升高,B4C-C复合粉体的石墨化度增大,B4C含量下降,1900℃时石墨化度达23.26%,B4C含量为20%左右,复合粉体中除部分微米、亚微米级的B4C外,85%以上为纳米级的B4C和部分石墨化炭黑. 添加复合粉体的低碳镁碳砖具有良好的常规物理性能、抗氧化性和热震稳定性.     

Microwave Absorption Properties of Polyaniline/Carbonyl Iron Composites

In this work, carbonyl iron (CI) containing polya- niline composites (PANI+CI) were prepared via in-situ polymerization of aniline in an aqueous solution containing different amounts of CI as the magnetic filler for the micro- wave absorbers. The incorporation of the magnetic powder to the PANI matrix was confirmed by X-ray diffraction (XRD), IR and SEM. Synthesized PANI+CI composite particles were subsequently added to an epoxy resin matrix to produce related R-PANI+CI composites. Study of thermal properties by thermogravimetric analysis revealed enhanced thermal stability of the composites. The electromagnetic-absorbing properties were studied by measuring the reflection loss in the frequency range of 8.0 to 12.0 GHz. The experimental results indicated that the electromagnetic wave absorbing properties of PANI+CI composites are dependent on the PANI/CI weight ratio. The good reflection loss of the composite at the optimum PANI/CI weight ratio of 1:6 suggests its potential applicability as a good radar absorber.     

Low Dielectric Loss Polytetrafluoroethylene/TeO2 Polymer Ceramic Composites

TeO₂ particle-filled PTFE composites were prepared by the powder processing technique. The structure and microstructure of the composites were investigated by X-ray diffraction and scanning electron microscopic methods. The effect of the ceramic content (0–0.6 volume fraction) of TeO₂ on the dielectric properties of the composites was studied at 1 MHz and 7 GHz. The dielectric constant and dielectric loss increased with an increase in the TeO₂ content. For 60 vol% of TeO₂, the composite has a dielectric constant of 5.4 and a loss tangent of 0.006 at 7 GHz. The measured dielectric constant (ɛ_r) is compared with the effective dielectric constant calculated using different theoretical models. The observed dielectric constants are in agreement with that calculated using effective medium theory. The coefficient of thermal expansion of the composites decreases with the TeO₂ content, reaching a minimum of 32 ppm/°C for 60 vol% loading.     

Titania-Coated Magnetite and Ni-Ferrite Nanocomposite-Based RADAR Absorbing Materials for Camouflaging Application

A novel core–shell-structured nanocomposite material based on titanium dioxide-coated magnetite and Ni-ferrite has been prepared for RADAR absorbing application in a X-band region. The coating of magnetic particles with TiO₂ was carried out by in situ hydrolysis of titanium tetrabutoxide, and the composite absorber sheets were prepared with epoxy resin. The morphological characterization of the magnetic particles was studied with field emission scanning electron microscope, transmission electron microscope, X-ray diffraction, and vibrating sample magnetometer analysis techniques. The measurement results confirmed the coating of magnetic particles with TiO₂ and reduction of the magnetization of magnetite and Ni-ferrite nanoparticles compared with the uncoated ferrite nanoparticles. Distribution of particle inside the matrix was studied with scanning electron microscope. Microwave absorption study in X-band (8–12 GHz) region was carried out with vector network analyzer. Results showed reflection loss values of ?26.5 db at 9.08 GHz for the magnetite coated with titanium dioxide/conducting carbon black containing sample which increased to ?45.7 db at 9.13 GHz for the Ni-ferrite coated with TiO₂/conducting carbon black formulation. It was observed that coating of magnetic particles resulted in the improvement in the microwave absorption.