纳米Ni粉的表面改性及电磁波吸收性能研究

使用稀盐酸处理纳米镍粉表面的Ni2O3,然后用十二烷基苯磺酸钠(SDBS)对纳米镍粉表面进行改性,采用活性试验、红外光谱、热分析等手段对改性后的粉体进行了表征,并通过矢量网络分析仪,利用同轴波导的方法对粒子进行了电磁参数的测定.将试验所得到的电磁参数数据通过计算机模拟转化成材料对电磁波功率损耗值.结果表明,稀盐酸可以去除纳米镍粉表面氧化层;用4%十二烷基苯磺酸钠(SDBS)改性纳米镍粉能够显著提高纳米镍粉在有机介质中的分散性,提高了电磁波吸收性能.     

导电纳米镍粉表面改性研究

为了提高纳米镍粉作为导电材料的分散性以及与基体的结合,对此进行了表面改性.使用稀盐酸处理纳米镍粉表面的Ni2 O3,然后用油酸对纳米镍粉表面进行改性,采用活性试验、红外光谱、热分析等手段对改性后粉体进行了表征,并对以改性纳米镍粉为填料的导电屏蔽涂料进行了电阻率和屏蔽效能的测试.结果表明:稀盐酸可以去除纳米镍粉表面氧化层;用5.5%油酸(Ni质量)改性纳米镍粉能够显著提高纳米镍粉在有机介质中的分散性,取得了良好的改性效果.     

纳米SiO2表面改性研究

以乙醇为分散介质,用硅烷偶联剂γ-(2,3-环氧丙基)氧化丙基三甲氧基硅烷(KH-560)对纳米SiO2进行表面改性.讨论了偶联剂用量对SiO2改性的影响,并采用红外光谱、热失重、扫描电镜、表面羟基滴定等手段表征改性效果.结果表明,硅烷偶联剂与纳米SiO2发生化学反应并接到SiO2表面,改性后的SiO2在有机物中的分散性明显改善.     

纳米镍粉的制备及其电磁屏蔽效能的研究

采用水合肼为还原剂,氯化镍为原料,在水和乙醇混合介质中,通过化学还原法制备了单分散性的金属镍纳米粉.X射线衍射(XRD)结果表明,所制备的样品是纯镍纳米粉,没有杂相存在.场发射扫描电子显微镜(FE-SEM)的结果表明,所制备样品的粒径均匀.纳米镍粉及纳米镍粉与微米镍粉混合的电磁屏蔽涂料的电磁屏蔽效能测量结果表明,纳米镍粉的加入,虽然会降低电磁屏蔽效能,但却能提高吸收损耗,原因是增大了磁损耗角正切,减少了电磁波对环境、设备造成的破坏及人类健康的危害.     

硅烷偶联剂对纳米二氧化硅表面接枝改性研究

利用硅烷偶联剂对纳米二氧化硅粉体进行超声表面改性,采用动态光散射粒度仪(DLS)、红外光谱(FT-IR)和透射电镜(TEM)等分析手段对表面改性前后的纳米二氧化硅进行表征。结果表明:硅烷偶联剂能够成功地对纳米二氧化硅进行改性,并且提高其分散性。经硅烷偶联剂改性的纳米二氧化硅活化率提高,团聚减少,粒子分布更加均匀。     

自纳米化电工纯铁表面合金化改性研究

利用高能喷丸(high energy slaot peening,HESP)法在电工纯铁表面获得了一定厚度的纳米晶层;同时采用在喷丸弹丸中添加镍粉和铬粉的方法,实现了电工纯铁表面自纳米化-合金化改性.运用金相显微镜、扫描电镜、X射线衍射分析以及电化学测试系统等手段对自纳米化层以及合金化层的组织结构进行了表征,重点对其耐...     

改性纳米金刚石增强增韧医用口腔复合树脂的研究

以爆轰法合成的纳米金刚石作为填料,加入到双酚A型口腔用光固化复合树脂中,研究了纳米金刚石对树脂性能的影响.金刚石用硅烷偶联剂进行表面改性.结果发现:偶联剂化学接枝到金刚石表面,改性后的金刚石在乙醇中的分散稳定性得到提高;加入0.2%(质量分数)的改性纳米金刚石后,复合树脂的挠曲强度和硬度分别提高35.4%和29.8%,改性金刚石的增强作用明显优于未经改性的金刚石;同时金刚石的加入也改善了树脂的韧性.     

KH570/聚苯乙烯双重改性纳米氮化铝粉末的研究

采用硅烷偶联剂KH570和苯乙烯对无机纳米AlN粉末表面进行双重改性,制备了表面有机改性纳米AlN粉末.采用红外光谱、热失重以及X射线衍射(XRD)对KH570/聚苯乙烯双重改性前后纳米AlN粉末进行了表征.结果表明:苯乙烯可以与硅烷偶联剂KH570共聚并连接在纳米AlN粉末表面;纳米AlN粉末最大失重速率温度由改性前的202.3℃上升到228.07℃;改性剂的用量约为纳米AlN粉末质量分数的2%～3%即可获得很好的改性效果,改性后的纳米AlN粉末即使在70℃的热水中浸泡24h也不会发生明显的水解,疏水性和抗水解性能显著提高.     

纳米氧化锌对液体硅橡胶导热性能的改进研究

以直接沉淀法合成了纳米氧化锌(ZnO),使用硅烷偶联剂对其进行表面改性,并制备了纳米ZnO与液体硅橡胶的复合材料,对改性前后纳米ZnO的结构进行了表征,并对复合材料的相关性能进行了研究。结果表明:通过接枝反应,硅烷偶联剂可以接枝到纳米ZnO表面,改性前后ZnO的晶型不发生变化;在较低添加量的情况下,纳米ZnO可以在一定程度上提高液体硅橡胶的力学性能,当添加量为2%时,改性前后纳米ZnO制备的液体硅橡胶复合材料的导热系数可以从0.189W/m.K分别提高到0.506W/m.K和0.61W/m.K。     

聚丙烯基纳米TiO2的表面改性

针对纳米二氧化钛(TiO2)颗粒粒径小、表面活性大、易团聚的问题,采用硅烷偶联剂KH-560对TiO2进行表面改性,并与聚丙烯树脂(PP)在双螺杆挤出机上熔融共混得到改性PP;通过FT-IR、TG、SEM等测试手段对改性纳米TiO2颗粒进行了表征,讨论了纳米TiO2的改性程度及其在PP中的分散性。结果表明:硅烷偶联剂已经成功的包覆在纳米TiO2的表面;同时在碱性环境下纳米TiO2表面包覆的有机物含量最多;当在碱性环境下表面改性的纳米TiO2为PP质量的3%时,在聚丙烯树脂中分散较均匀。     

甘蔗渣显微结构对聚乳酸/甘蔗渣复合材料结构与性能的影响

采用碱处理、硅烷偶联剂处理以及碱处理配合硅烷偶联剂处理等方式改性甘蔗渣(BF),采用傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)、X射线光电子能谱(XPS)、热重分析(TGA)以及力学性能测试等研究改性后BF结构的变化。结果表明,不同改性方法均明显改变了BF的结构及改性剂的键合方式。碱处理能够去除BF中的半纤维素等小分子聚合物以及部分非晶区的纤维素,导致BF热稳定性降低,结晶度上升。碱液浓度偏高以及碱处理时间过长会导致BF的纤维表面原纤化,虽然能增加与偶联剂反应的面积,但BF的强度大大下降,不利于BF的增强作用。因此,硅烷偶联剂处理的BF/PLA复合材料的相容性及力学性能最佳,其次为碱处理配合硅烷偶联剂处理的BF/PLA复合材料,最后为碱处理的BF/PLA复合材料。     

树脂基Fe纳米粒子及碳纤维复合吸波平板的制备与性能

以Fe纳米粒子(Fe NPs)为吸波剂,偶联剂KH550为表面改性剂,碳纤维(CFs)作为增强及电磁波反射相,环氧树脂(ER)作为基体,制备多种吸波平板并对其综合性能及相关机制进行研究。结果表明:平板的吸波性能随Fe NPs和CFs含量的增加而提高,吸收剂浓度梯度分布有助于形成特定频段的共振吸收;平板对电磁波损耗具有明显的各向异性,表现为CFs垂直电磁波入射方向时性能优于平行情况,当Fe NPs的含量为30%(质量分数,下同),CFs为5.52%,板厚为4.56mm时,最小反射损耗为-26.8dB(4.9GHz);同时,CFs可改善平板的抗弯性能,当Fe NPs为30%时,弯曲强度相比于纯树脂时仅降低了5.81%。     

Improved electrical insulating properties of LDPE based nanocomposite: Effect of surface modification of magnesia nanoparticles

Three silane coupling agents with amino, long alkyl chain or vinyl functional groups were used to modify magnesia (MgO) nanoparticles. The modified nanoparticles were then mechanically mixed with low-density polyethylene (LDPE) to fabricate insulating nanocomposites. The average size of the modified MgO aggregates dispersed in LDPE matrix was below 100 nm. The pulsed electroacoustic method indicated that the MgO nanoparticles regardless of surface modification were effective to suppress the packet-like charge injection and accumulation in the LDPE sample, decrease the permittivity and tan δ, and also improved the direct-current breakdown strength of LDPE at different temperatures. The best insulating properties were found in the case of vinyl-silane-modified-MgO/LDPE samples probably owing to the improved interfacial adhesion. A multi-core model was used to discuss the results obtained.     

表面改性对PVC/稻糠发泡复合材料的影响

研究了纳米CaCO3、硅烷偶联剂、甲基丙烯酸甲酯(MMA)改性稻糠对PVC/稻糠发泡复合材料性能的影响.结果表明:纳米CaCO3能改善稻糠的耐热性,用硅烷偶联剂处理稻糠的发泡复合材料冲击性能好于用MMA微波处理稻糠发泡复合材料;而用MMA微波处理稻糠的发泡复合材料在拉伸性能、弯弹性模量及加工性能优于硅烷偶联剂处理的稻糠发泡复合材料.     

Effect of additive ratio of mixed silane alkoxides on reactivity with TiO2 nanoparticle surface and their stability in organic solvents

To improve stability of TiO₂ nanoparticles in various organic solvents, their surface was modified using a mixture of silane coupling agents having hydrophobic and hydrophilic groups. Decyltrimethoxysilane (DTMS) and phenyltrimethoxysilane (PTMS) were used as the former and 3-aminopropyltrimethoxysilane (APTMS), as the latter. First, effects of mixing ratios of silane coupling agents on reactivity with TiO₂ nanoparticle surfaces were investigated. The addition of APTMS increased the pH value of TiO₂ nanoparticle suspension due to the presence of the amine group and largely affected to the reacted amount of hydrophobic silanes. Next, relationships between the reacted amounts of silanes and their dispersion stability in various organic solvents were then investigated. Surface-modified TiO₂ nanoparticles were re-dispersible into low-polar solvents such as hexane, toluene, and THF when the reacted amount of hydrophobic silane was relatively high; however, TiO₂ nanoparticles were re-dispersible in highly polar solvents when the reacted amount of hydrophilic silanes increased. By controlling the amount of hydrophilic and hydrophobic silanes added, it is possible to effectively improve the dispersion stability of TiO₂ nanoparticles in various organic solvents.     

蒙脱土/环氧树脂复合材料的制备及性能研究

先选择3种比例的KH550、KH560和KH570硅烷偶联剂改性蒙脱土,然后以5%(质量分数)的量加入到环氧树脂中,电磁搅拌1h后加入聚酰胺树脂,固化0.5h后涂刷.XRD和TGA分析表明硅烷偶联剂加入到了蒙脱土中;FT-IR分析表明硅烷偶联剂与蒙脱土存在相互作用;电化学阻抗谱(EIS)表明0.4%KH570改性的蒙脱...     

Nanosilica/PMMA composites obtained by the modification of silica nanoparticles in a supercritical carbon dioxide–ethanol mixture

Nanosilica/poly(methyl methacrylate) (PMMA) composites are used to improve the mechanical properties of neat PMMA polymer. In order to obtain superior mechanical properties, it is essential to achieve good bonding between the SiO₂ nanoparticles and the PMMA matrix, which is typically achieved by coating silica nanoparticles with silane coupling agents. In this study, conventional and supercritical coating methods were investigated together with their influence on the mechanical properties of the obtained nanosilica/PMMA composites. The results indicate advantageous properties of nanosilica modified in the supercritical phase of carbon dioxide and ethanol in terms of particle size distribution, amount of coated silane, and dispersion in the PMMA matrix. Careful dispersion of the starting silica nanoparticles in ethanol at low temperatures in order to obtain a nanosilica sol plays an important role in deagglomeration, dispersion, and the coating process. The resulting nanosilica/PMMA composite containing nanoparticles obtained by supercritical processing of the nanosilica sol showed an increase in hardness by 44.6% and elastic modulus by 25.7% relative to neat PMMA, as determined using the nanoindentation technique. The dynamic mechanical analysis reveals that addition of nanoparticles as nanosilica sol and nanosilica gel enhances composite storage modulus by about 54.3 and 46.5% at 40 °C. At the same temperature, incorporation of modified silica nanoparticles with conventional method leads to an increase of 15.9% for the storage modulus, probably due to a large silica particle size and lower silane content in this sample.     

不同偶联剂改性PTW对PP/GF复合材料性能的影响

目的研究六钛酸钾晶须表面改性对聚丙烯复合材料的力学性能影响,以探索最佳表面改性手段。方法分别采用硅烷偶联剂KH550、KH570、正十二烷基三甲氧基硅烷,钛酸酯偶联剂NDE311、改性六钛酸钾晶须(PTW),然后将改性过的六钛酸钾晶须、玻璃纤维、聚丙烯通过熔融共混制得聚PP/GF/PTW复合材料。结果比较六钛酸钾晶须经不同偶联剂改性前后对聚丙烯/玻璃纤维复合材料性能的影响,发现改性过的六钛酸钾晶须可改善复合材料的力学性能。比较不同偶联剂改性六钛酸钾晶须对聚丙烯/玻璃纤维复合材料性能的影响,发现经KH550偶联剂处理后,与未改性相比,复合材料的弯曲性能提高了58.63%,拉伸性能提高了16.07%,冲击性能提高了63.1%。结论六钛酸钾晶须经KH550偶联剂处理后,复合材料的综合性能最好。     

The effect of the coupling agents KH550 and KH570 on the nanostructure and interfacial interaction of zinc oxide/chiral poly(amide–imide) nanocomposites containing l-leucine amino acid moieties

In this article, a series of optically active poly(amide–imide)/zinc oxide nanocomposites (PAI/ZnO NCs) with different ZnO contents were prepared by ultrasonic technique. For better dispersion of nanoparticles (NPs) in the PAI matrix, their surface was modified with two different silane coupling agents. Then, the effects of two linkers on dispersity of NPs, thermal stability and UV–Visible spectra of resulting NCs were investigated. The morphological structures, thermal, and UV properties of the prepared NCs with two different coupling agents were studied by X-ray diffraction, transmission electron micrograph, field emission scanning electron microscopy, thermogravimetric analysis, and UV–Visible analysis. These data demonstrated that the surface-modified ZnO NPs were homogeneously dispersed in the PAI matrix. However, in the case of KH570 the better dispersity is more pronounced.