A study of the mechanical behaviour on fibre reinforced hollow microspheres hybrid composites

This paper presents the results of an investigation into the effects of hollow glass microsphere fillers and of the addition of short fibre reinforcements on the mechanical behaviour of epoxy binding matrix composites. Properties like flexural stiffness, compressive strength, fracture toughness and absorbed impact energy, were studied. The specimens were cut from plates produced by vacuum resin transfer moulding having a microsphere contents of up to 50% and with fibre reinforcement up to 1.2% by volume. The tests performed with unreinforced composites show that flexural and compressive stiffness, maximum compressive stresses, fracture toughness and impact absorbed energy decrease significantly with increasing filler content. However, in terms of specific values, both flexural and compressive stiffness and impact absorbed energy increase with microsphere content. The addition of glass fibre produces only a slight improvement in the flexure stiffness and fracture toughness, while increasing significantly the absorbed impact energy. In contrast, the addition of a small percentage of carbon fibres produces an important improvement in both fracture toughness and flexure stiffness, when hybrid composites with 0.9% carbon fibre are compared to unreinforced foam, but did not improved absorbed impact energy.     

Strength of different types of hollow glass microspheres

The results of comparative tests are presented for the hydrostaitc strength of hollow glass microspheres produced by different methods: by the sol-gel method and from powders of presynthesized glass.Translated from Prolem Prochnosti, No. 5, pp. 68–70, May, 1991.     

Investigation of the mechanical behavior and vibration characteristics of thin walled glass/carbon hybrid composite beams under a fixed-free boundary condition

In the present work, woven fabric glass laminate is modified by interplying high modulus carbon fabric layers for improving the stiffness to weight ratio to enable good performance in dynamic conditions. The glass, carbon, and hybrid of glass/carbon laminates were fabricated with two different stacking sequences by hand layup method and tested for evaluating the mechanical properties with considerable trials. The vibration characteristics of composite beams were experimentally studied by impulse excitation techniques under fixed-free boundary conditions. The stacking sequence of beams influences the mechanical properties and vibration characteristics. The modal response of tested samples are compared and discussed.     

Factors influencing the deposition of hydroxyapatite coating onto hollow glass microspheres

Hydroxyapatite (HA) and HA coated microcarriers for cell culture and delivery have attracted more attention recently, owing to the rapid progress in the field of tissue engineering. In this research, a dense and uniform HA coating with the thickness of about 2 μm was successfully deposited on hollow glass microspheres (HGM) by biomimetic process. The influences of SBF concentration, immersion time, solid/liquid ratio and activation of HGM on the deposition rate and coating characteristics were discussed. X-ray diffraction (XRD) and Fourier transform infrared spectrum (FTIR) analyses revealed that the deposited HA is poorly crystalline. The thickness of HA coating showed almost no increase after immersion in 1.5SBF for more than 15 days with the solid/liquid ratio of 1:150. At the same time, SBF concentration, solid/liquid ratio and activation treatment played vital roles in the formation of HA coating on HGM. This poorly crystallized HA coated HGM could have potential use as microcarrier for cell culture.     

中空玻璃微球近期技术发展和应用

综述了国内外人造中空玻璃微球的制造技术及发展趋势,着重叙述了中空玻璃微球制备吸波材料、中空玻璃微球制备高强度浮力材料的技术发展状况,并介绍了国内外主要生产厂家及产品应用情况.     

Chemical deposition of silver shells on the surface of hollow glass microspheres

This article reports the chemical deposition of silver shells on the surface of hollow glass microspheres. This was accomplished by using titanium dioxide, derived from titanium (IV) tetra-n-butoxide, as the surface modifier. Two routes of formation of thin titanium dioxide layers on the substrate were compared in terms of composition and properties: photochemical approach and atmospheric hydrolysis. The structure and composition of the samples were characterized by atomic force microscopy, scanning electron microscopy, IR spectroscopy, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The resulting thickness of uniform silver shells on the surface of microspheres averaged out at 1.0–1.25 μm.     

空心玻璃微珠/PP复合材料的制备及性能研究

采用共混与注塑工艺制备出空心玻璃微珠/PP复合材料.通过高倍偏光显微镜、傅里叶红外光谱仪(FTIR)、扫描电镜(SEM)等对材料的结构进行了表征,重点研究了未改性与改性的空心玻璃微珠对PP复合材料力学性能影响.结果表明:改性后的空心玻璃微珠在PP复合材料中分散均匀而且具有致密的内部结构,并明显的改善复合材料的拉伸、弯曲强度,最佳填充量为15%.     

空心玻璃微珠/PS隔热材料的制备及其性能

采用原位聚合方法制备以聚苯乙烯为基体掺杂一定量中空玻璃微珠的复合材料.采用扫描电子显微镜(SEM),原子力显微镜(AFM),紫外可见光分光光度计(UVPC),热导率常数测试仪(TCCT)等主要对样品材料的形貌,反射率,热导率,吸水率等性能进行表征和分析,研究其隔热机理.结果表明:玻璃微珠在聚苯乙烯基体中分散均匀;添加玻璃微珠后,材料的热导率随着玻璃微珠量的增加呈先下降后上升继而又下降的趋势;材料的反射率有着明显的提高,在可见光波段基本可达90％以上,且随着玻璃微珠含量的增加总体上是先上升继而趋于平缓;由热导率和反射率的数据说明该材料的隔热机理是阻隔型和反射型的综合作用.     

Synthesis of hollow glass-ceramics microspheres via template method

Hollow glass-ceramics microspheres (HGCM) were successfully fabricated by a simple technique using polyacrylamide microspheres (PAM) as template. The corresponding HGCM were obtained by a thermal treatment of the core-shell microspheres, which were synthesized with organic template method. The effects of the concentration of glass powder, the Hydrophile-Lipophile Balance (HLB) value, and the amount of pre-adsorbed water on the morphologies of the core-shell microspheres and HGCM have been investigated. The size, morphology, core-shell structure and crystalline phase of HGCM and core-shell microspheres were determined via XRD, SEM and TGA. The influences of initiator and surfactant on the monodispersity and average diameter of PAM were investigated via SEM. The results showed that: (a) the average diameter and monodispersity of PAM can be controlled by varying the amount of initiator and surfactant, and (b) the agglomeration of core-shell microspheres and HGCM can be reduced using PAM with pre-adsorbed water and adjusting the HLB value. In addition, the amount of solid beads decreases obviously by reducing the concentration of glass powder and adjusting the HLB value.     

On the use of a neural network to characterize the plasma etching of SiON thin films

Using a generalized regression neural network (GRNN), plasma etching of oxynitride thin films was modeled. The etch process was characterized by means of a statistical experiment. A genetic algorithm was employed to improve prediction performance by optimizing multiparameterized training factors. Compared to a conventional GRNN model, the constructed etch rate model demonstrated an improvement of about 60% in the prediction performance. 3-D plots were generated to qualitatively interpret etch mechanisms while validating the predictions with experimental data. In separating physical and chemical effects, both dc bias and profile angle variations were effectively utilized. The source power affected significantly the etch rate irrespective of changes in the bias power or C₂F₆ flow rate. For pressure variations, the etch rate was estimated to be dominated by chemical etching. The complex effect of C₂F₆ flow rate could be explained by dominant chemical etching or polymer deposition.     

水热法制备高反射率TiO2壳层中空玻璃微球

以钛酸四丁酯、盐酸、去离子水、中空玻璃微球(HGM)为原料,乙醇为溶剂,采用水热合成法制备了高反射率的锐钛矿型TiO₂壳层HGM(HGM@TiO₂)。采用SEM、EDS、FTIR、XRD、UV-VIS-NIR、导热系数仪研究了钛酸四丁酯用量对微球的表面形貌、表面化学成分、物相结构、反射性能、导热系数的影响。结果表明:锐钛矿型TiO₂成功包覆于HGM表面,包覆形貌完整且均匀,并且包覆层厚度随着钛源用量的增加而变厚;与原始HGM相比,HGM@TiO₂的导热系数有小幅上升,最大上升幅度仅为0.007 W/(m·K),证明TiO₂的包覆对HGM的隔热性能的影响不大;包覆后的HGM的光谱反射率在可见光波段和近红外波段的反射率得到大幅提升,最大提升幅度为13%,HGM@TiO₂的最高反射率达到90%以上。      

Fabrication of CuO/Fe2O3 hollow hybrid microspheres

CuO/Fe₂O₃ hollow hybrid spheres with the size of 3–5 μm were successfully synthesized by a convenient hydrothermal method, using FeSO₄·7H₂O and CuSO₄·5H₂O as the starting materials and urea as the homogeneous precipitant. The samples were characterized by XRD, TEM, ED, SEM, EDX, IR and XPS measurements. XRD and XPS analyses indicated that the nanostructured materials consisted of CuO and α-Fe₂O₃. TEM and SEM measurements showed that the morphology of binary metal oxide was in the shape of hollow sphere. Careful observation from SEM measurements could find that CuO/Fe₂O₃ hollow microsphere shell was composed of uniform and dense metal oxide nanorods with about 20–40 nm in diameter and 100–200 nm in length. Moreover, the influence of calcination temperature on the thermal stability of the hollow structures was investigated. It showed that the hollow structure was stable after being calcined at 300 °C for 2 h. The formation mechanism of the CuO/Fe₂O₃ hollow spheres under hydrothermal condition was discussed.     

SiO2空心微球的制备表征及摩擦性能

以分散聚合法制备的聚苯乙烯(PS)微球为有机模板, 以正硅酸四乙酯(C₈H₂₀O₄Si)为无机前躯体物料, 通过静电吸附作用成功地制备了纳米 PS-SiO₂ 复合微球和SiO₂单分散空心结构。通过红外(FTIR)、热重(TG)、透射电镜(TEM)、扫描电镜(SEM) 和热重分析仪(TGA)等手段对纳米复合材料进行了表征, 并对产物的抗磨性能进行了测试。结果表明, 该方法可一次性制备大量的复合微球, 这些微球的直径约为0.7 μm, 分散性能良好。在煅烧去除模板后, 得到了保持完整的空心纳米 SiO₂ 结构, 微球的球壳稳定性较好。摩擦实验表明, 添加了2 wt%空心微球的植物油在较低载荷工况下具有优异的减磨性能, 摩擦系数可低至0.058。      

Dissolution behavior of hollow hydroxyapatite microspheres immersed in deionized water

Hollow hydroxyapatite (HA) microspheres were fabricated by plasma spraying method. These microspheres were immersed in deionized water for different periods of time to investigate their dissolution behavior with the starting HA powders as contrast. The results showed that although having a relatively lower crystallinity, the dissolution rate of the HA microspheres is somewhat lower than that of HA powders, which was due to the very dense surface layer of the microspheres. Moreover, open pores were seen on the surface of hollow microspheres after immersion. These results suggest that there might be a novel application in drug delivery for the hollow HA microspheres.     

空心玻璃微球表面接枝聚苯乙烯及其性能研究

空心玻璃微球表面改性有利于改善其与基体间的相容性,提高复合泡沫性能.通过接枝聚苯乙烯对空心玻璃微球进行表面处理,采用SEM、IR、热失重等方法分析了反应条件对接枝的影响.结果表明,接枝反应过程中提高反应温度、延长反应时间有利于接枝率的提高,但温度过高会加速单体自聚,降低接枝率.接枝处理后,随着聚合物层的增厚,空心玻璃微球表面缺陷减小,破损率降低,抗压强度得到一定程度提高.     

Synthesis and in vitro bioactivity of novel mesoporous hollow bioactive glass microspheres

The remarkable tissue-repairing bioactivity and biocompatibility of bioactive glass make it suitable for a wide range of applications. Here, novel mesoporous hollow bioactive glass microspheres (MHBGMs) with a uniform diameter range of 2-5 µm were prepared by a sol-gel method. Structural characterization indicated that the shell of hollow sphere had a mesopore size range between 2 and 10 nm and a thickness about 500 nm. The in vitro bioactivity test indicated that the novel structure exhibited high in vitro bioactivity. The uniform microspherical morphology and mesoporous hollow structure of MHBGMs, together with their high bioactivity, turn them into a good candidate as an injectable and drug-loading biomaterial for in vivo tissue regeneration and drug control release.     

空心玻璃微珠表面包覆Ni-P／Co-Fe-P复合镀层的研究

通过化学镀在空心玻璃微珠（HGM）表面沉积了镍磷合金颗粒镀层，利用偶联取代传统的粗化处理，结合适当的镀覆工艺实现了镀层与微珠的紧密结合并达到了均匀完整包覆；在此基础上，进行了镍磷镀层表面湿化学还原法包覆钴铁合金的研究。利用扫描电子显微镜、X射线能谱仪、X射线衍射仪及振动样品磁强计对包覆层的形貌、组成、晶体结构和改性后微珠的静磁性能进行了分析测试。结果表明，复合镀层由非晶态合金组成，其中镍磷镀层为单层颗粒膜，而后续沉积的钴铁合金镀层呈条带状生长于镍磷镀层表面；沉积钴铁合金后微珠的磁性有了明显改善。     

空心玻璃微珠/硬质聚氨酯泡沫复合材料的制备及性能

以空心玻璃微珠(HGM)为添加剂,采用一步法全水发泡制备了一系列HGM/硬质聚氨酯泡沫(RPUF)复合材料。通过SEM、TG、极限氧指数(LOI)和水平燃烧,研究了HGM/RPUF复合材料的泡孔结构、炭层形貌、热稳定性及阻燃性能。采用万能材料试验机测试了HGM/RPUF复合材料的压缩强度和压缩弹性模量。采用热重-傅里叶红外光谱(TG-FTIR)研究了HGM/RPUF复合材料燃烧过程中的气相产物。研究表明,HGM有成核剂作用,可以缩小HGM/RPUF复合材料泡孔孔径。HGM在燃烧过程中迁移到炭层表面,促进形成致密厚实的炭层。当加入5.4wt% HGM时,HGM/RPUF复合材料的压缩强度及压缩弹性模量分别提高至0.14 MPa和4.53 MPa,相对RPUF,分别提高了37.30%和67.16%。同时发现,HGM能明显抑制HGM/RPUF复合材料在燃烧过程中CO的释放,有效提高了其火灾安全性。      

Investigation of thermal conductivity and dielectric properties of LDPE-matrix composites filled with hybrid filler of hollow glass microspheres and nitride particles

The hybrid filler of hollow glass microspheres (HGM) and nitride particles was filled into low-density polyethylene (LDPE) matrix via powder mixing and then hot pressing technology to obtain the composites with higher thermal conductivity as well as lower dielectric constant (D_k) and loss (D_f). The effects of surface modification of nitride particles and HGMs as well as volume ratio between them on the thermal conductivity and dielectric properties at 1 MHz of the composites were first investigated. The results indicate that the surface modification of the filler has a beneficial effect on thermal conductivity and dielectric properties of the composites due to the good interfacial adhesion between the filler and matrix. An optimal volume ratio of nitride particles to HGMs of 1:1 is determined on the basis of overall performance of the composites. The thermal conductivity as well as dielectric properties at 1 MHz and microwave frequency of the composites made from surface-modified fillers with the optimal nitride to HGM volume ratio were investigated as a function of the total volume fraction of hybrid filler. It is found that the thermal conductivity increases with filler volume fraction, and it is mainly related to the type of nitride particle other than HGM. The D_k values at 1 MHz and microwave frequency show an increasing trend with filler volume fraction and depend largely on the types of both nitride particles and HGMs. The D_f values at 1 MHz or quality factor (Q × f) at microwave frequency show an increasing or decreasing trend with filler volume fraction and also depend on the types of both nitride particle and HGM. Finally, optimal type of HGM and nitride particles as well as corresponding thermal conductivity and dielectric properties is obtained. SEM observations show that the hybrid filler particles are agglomerated around the LDPE matrix particles, and within the agglomerates the smaller-sized nitride particles in the hybrid filler can easily form thermally conductive networks to make the composites with high thermal conductivity. At the same time, the increase of the value D_k of the composites is restricted due to the presence of HGMs.