针状氧化锌的控制合成

采用简单的低温陈化法,以ZnCl2和NaOH为原料,阴离子表面活性剂SDS或SDBS为添加剂,成功制备了不同长径比的一维结构ZnO晶体.利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对样品进行了表征.通过跟踪ZnO形成过程中Zn(Ⅱ)离子浓度的变化情况,初步探讨了阴离子表面活性剂对ZnO晶体生长的作用机理.结果表明,阴离子表面活性剂能够有效降低ZnO的成核、生长速率,促进其沿[0001]方向生长成为长径比较大的针状形貌.     

纳米级β-Ni(OH)2的制备和放电性能

本文采用均相沉淀法和无水乙醇溶剂法制备出了纳米级β-Ni（OH）₂运用XRD、TG、DTA、TEM及ICP测试对制备的样品作了分析研究．制备过程中表面活性剂、转型条件及后处理温度的选择对样品性质影响很大,对纳米β-Ni（OH）₂进行了充放电实验研究．     

纳米级β-Ni(OH)2的制备和放电性能

本文采用均相沉淀法和无水乙醇溶剂法制备出了纳米级β-Ni（OH）₂运用XRD、TG、DTA、TEM及ICP测试对制备的样品作了分析研究．制备过程中表面活性剂、转型条件及后处理温度的选择对样品性质影响很大，对纳米β-Ni（OH）₂进行了充放电实验研究．     

针状纳米碳酸钙的制备研究

采用鼓泡碳化法，以无机酸A为添加剂，通过对反应温度，反应物浓度，气体流量和气体分布板孔状径大小等各影响因素的控制，得到制备针状纳米碳酸钙的优化工艺条件，最终制得了平均粒径为20nm，长径比约为18,且分散性能良好的纳米碳酸钙，并用TEM和XRD对产物粒子进行了表征。     

阻燃剂级氢氧化镁制备工艺研究

以MgO为原料,采用水化法制备阻燃剂级Mg(OH)2,研究了水化过程中温度、时间、MgO粒度对水化转化率的影响,采用了一种特殊的结晶助长剂S320用于水化反应后的Mg(OH)2助长结晶,所得Mg(OH)2由助长前的0.1～0.2微米溶胶状颗粒增长至0.5～1微米的结晶态颗粒。     

真空法制备纳米四针状氧化锌晶须结构和形貌的研究

以金属锌为原料,研究了真空条件下纳米四针状氧化锌晶须(T-ZnOw)的制备,考察了反应条件对氧化锌结晶形貌的影响.表面能谱证实产物只含锌和氧原子,但氧原子数少于化学计量,表明T-ZnOw在缺氧环境中生长.XRD物相分析表明:产物为纯的六方晶系纤锌矿结构;SEM研究表明:分子筛用量、反应温度、体系压力对产物的形态影响很大.     

纳米针状锌粉的制备与表征

实验在一种新型的滚压振动磨上进行，原料锌粉经数小时研磨后，通过X射线多晶衍射仪和透射电子里微镜检测，结果显示：在不同研磨时间内，样品由球状变成棒状，杆状及针片状形态，且拉度均匀。平均拉径均在60nm以下，晶型为密排六方晶格。     

低温水热法制备形貌可控纳米α-Fe2O3的研究

以FeCl3.6H2O、尿素为主要原料,以聚乙烯吡咯烷酮(PVP)或十二烷基苯磺酸钠(SDBS)为表面活性剂,乙二醇为分散剂,采用低温水热法制备了不同形貌的α-Fe2O3,分析讨论了加入表面活性剂及乙二醇作为分散剂对产物形貌的影响,采用热重-差热分析(TG-DTA)研究样品的热分解过程,利用X射线衍射(XRD)、扫描电镜(SEM)对样品成分、粒度、形貌等进行了表征分析。结果表明:表面活性剂和分散剂可以控制颗粒的形貌,加入不同的表面活性剂、分散剂及控制其用量可以得到形貌不同的纳米α-Fe2O3。     

纳米针状锌粉的制备与表征

实验在一种新型的滚压振动磨上进行,原料锌粉经数小时研磨后,通过X射线多晶衍射仪和透射电子显微镜检测,结果显示在不同研磨时间内,样品由球状变成棒状、杆状及针片状形态,且粒度均匀.平均粒径均在60nm以下,晶型为密排六方晶格.     

用Ni(OH)2浆化氢还原法制备纳米金属镍粉的反应机制

用Ni(OH)2浆流水热氢还原法制备了纳米金属镍粉，通过对不同反应阶段样品性质的分析，研究了反应机制，结果表明，在酸性条件下，通过复盐离解出的镍离子在溶液中与氢发生反应，在碱性条件下，Ni(OH)2固体颗粒直接与活性氢发生反应。     

使用硅油-水体系制备纳米氢氧化镁

以硫酸镁和氢氧化钠为主要原料,用化学沉淀法在硅油-水体系中制备氢氧化镁阻燃剂,用X射线衍射(XRD)、透射电镜(TEM)、傅里叶变换红外光谱(FT-IR)和热重分析仪(TGA)对产物的形貌、粒径、晶型结构和热稳定性进行表征,研究了反应时间、温度、搅拌速度、盐和碱溶液浓度、加料方式等因素对氢氧化镁形貌和分解温度的影响.结果表明:当反应时间为6 h、反应温度为60℃、搅拌速度为1500 r/min时,制得质量和性能较好的纳米氢氧化镁.     

水热法合成Nd(OH)3和Nd2O3纳米棒的形貌控制研究

以工业高纯氧化钕微粉为起始原料,在不使用表面活性剂的情况下通过简单的水热合成法制备出氢氧化钕一维纳米棒,采用X射线衍射仪、扫描电子显微镜和透射电子显微镜对其组成及形貌结构进行了系统表征.研究表明,合成过程中水热体系的反应温度、pH值、反应物初始浓度及反应时间对最终产物的形貌结构具有较大影响,当反应温度为180℃、溶液体系pH值约为9.5、Nd3 浓度为0.12mol/L时,经12h反应可以大量制备形态均一、相纯度高的六方相氢氧化钕晶体纳米棒.该氢氧化钕纳米棒在空气气氛下500℃焙烧后形成具有体心立方结构的C型Nd2O3,该Nd2O3仍具有一维纳米棒形貌.     

Core-shell magnesium hydroxide/polystyrene hybrid nanoparticles prepared by ultrasonic wave-assisted in-situ copolymerization

In this paper, vinylated magnesium hydroxide (MH) nanosheets were prepared with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and pristine MH nanosheets, then the MH/polystyrene (PS) hybrid nanoparticles were prepared by ultrasonic wave-assisted in-situ copolymerization of vinylated MH nanosheets and styrene (St). The morphology, thermal stability and chemical structure of the final products were investigated in detail with transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR). The TEM and FTIR results showed that the uniformly-dispersed core-shell structure of MH/PS nanocomposites with MH-cores and PS-shell was formed. TGA indicated that the covalent interaction between PS and MH improved the thermal stability of PS. A possible formation mechanism of the MH/PS core-shell nanocomposites was also proposed.     

Gel-spun fibers from magnesium hydroxide nanoparticles and UHMWPE nanocomposite: The physical and flammability properties

In this study, magnesium hydroxide [Mg(OH)₂] nanoparticles were successfully incorporated into ultrahigh molecular weight polyethylene (UHMWPE) to produce nanocomposite fibers with reduced flammability. To improve the dispersibility in processing solvent (decalin) and the compatibility with UHMWPE, the Mg(OH)₂ nanoparticles were firstly modified with oleic acid. Fourier transform infrared spectroscopy indicated that the oleic acid was covalently bonded on the surface of Mg(OH)₂ nanoparticles and formed a coating layer. The modified Mg(OH)₂ could disperse evenly and stably in decalin. The UHMWPE/decalin solutions with different percentages of Mg(OH)₂ were gel-spun and then hot drawn to yield UHMWPE nanocomposite fibers. The addition of Mg(OH)₂ nanoparticles altered the mechanical properties of the fibers by affecting their maximum draw ratio. High loading of the nanoparticles would decrease both strength and modulus of the fibers. The thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) under air flow demonstrated their flammability could be remarkably reduced. The starting thermal decomposition temperature was increased by 30 °C. Their combustion peak temperatures were also increased significantly.     

Cellular toxicity of inorganic hydroxide nanoparticles

Layered double hydroxides (LDHs), anionic clays, have attracted increasing interest as nanovehicles for delivering genes, drugs, and bio-active molecules into cells. However, no attempts have been made to evaluate the potential undesirable effects of LDH nanoparticles. The cytotoxicity of LDHs with different chemical compositions (ZnAl- and MgAl-LDH) was systematically evaluated in various cell types, such as human normal cells, carcinoma cells, and red blood cells, by measuring cell viability, cell proliferation, membrane damage, and hemolytic effect. No significant cytotoxic effects could be seen in both cases, but ZnAl-LDH was determined to be slightly more toxic than MgAl-LDH in terms of membrane damage and hemolysis induction. It is, therefore, expected that LDHs could be promising candidates for novel inorganic drug delivery carriers.     

Agglomeration of magnesium oxide particles formed by the decomposition of magnesium hydroxide

The agglomeration process of MgO powder derived from Mg (OH)₂ was investigated at fixed temperatures of 600, 800, 900 and 1200° C; these temperatures were chosen as representative of four regions, i.e. below 600° C, 650 to 850° C, 850 to 1050°C and 1050 to 1200° C previously reported. At 600° C, coherent crystallites coalesced within the heating time of 60 min; on further heating till 300 min, the primary particles which consisted of crystallites grew rapidly. The original Mg (OH)₂ framework or pseudomorphs, composed of minute crystallites and primary particles, still remained in the powder. At 800° C, the pseudomorphs had disintegrated into fragments. The crystallite growth and primary particle growth were accelerated with increasing the heating times beyond 60 min. At 900° C, a further fragmentation of agglomerates occurred with increasing the heating times; the crystallite and primary particle growth in fragments brought about the pore coalescence. At 1200° C, the crystallite and primary particle growth proceeded with the coarsening of pores; on heating beyond 240 min, the crystallites and primary particles grew rapidly due to the entrapment of pores within them.     

Controlled growth of magnesium hydroxide crystals and its effect on the high-temperature properties of cotton/magnesium hydroxide composites

Controlled magnesium hydroxide particles were assembled successfully on the surface of cotton fibers for the improvement of flammability and thermal stability of cotton/magnesium hydroxide composites. Unlike previous researches where magnesium hydroxide particles have been blended into polymer matrix, self-assembly of particles onto the fiber surface demonstrated in this research provided substantially excellent properties. The morphology, structure and properties of cotton/magnesium hydroxide composites were characterized. Here, the fibers exhibited a swelling surface after the urea-modification, resulting in the more amounts of magnesium hydroxide crystals growing. Without the presence of sodium chloride, the particles self-assembled into lamellar-like structure on the surface of cotton fibers and into rod-like structures with the presence of sodium chloride thereby enabling us to control the growth of the particles. The vertical flammability test showed that the introduction of sodium chloride resulted in the change of morphology of magnesium hydroxide crystals, which had the important effect on the fire-proofing properties of cotton/magnesium hydroxide composites. The weight loss of origin fabrics, citric acid-modified cotton fabrics with Mg(OH)₂ crystals grew with salts and urea/citric acid-modified cotton fabrics with Mg(OH)₂ crystals grew with salts were 81.5%, 57.4% and 48.9% respectively when heated to a temperature of 500 °C.     

Agglomeration of magnesium oxide particles formed by the decomposition of magnesium hydroxide

Agglomeration of magnesium oxide (MgO) particles was studied by decomposing magnesium hydroxide (Mg(OH)₂). The properties of agglomerates varied according to the decomposition temperature region: (i) below 650° C, (ii) 650° C to 850° C, (iii) 850° C to 1050° C, and (iv) 1050° C to 1200°C. In region (i), the original Mg(OH)₂ frameworks or pseudomorphs remained in the powder and showed agglomeration. The strength of agglomerates containing the pesudomorphs was about 50 MPa; the primary particles in pseudomorphs are bonded chemically by the interaction of MgO and residual water. In region (ii) the pseudomorphs began to show some fragmentation: the bonding strength of these pseudomorphs reduced rapidly. In region (iii), both crystallite and primary particles were grown by the sintering; this growth may be due to an increase in contact area based on the collapse of pseudomorphs. The primary particles whose necks were grown by the sintering could be easily pulled apart by grinding. In region (iv) pore growth due to the rearrangement of primary particles caused the suppression of both densification rate and crystal growth of MgO.     

Morphology and composition of nanograde calcium phosphate needle-like crystals formed by simple hydrothermal treatment

Nanograde calcium phosphate needle-like crystals are prepared from wet synthesized Ca–P precipitates by simple hydrothermal treatment at 140°C and 0.3 MPa for 2 h. The morphology of these crystals is observed by transmission electron microscopy (TEM). The phase composition is tested through X-ray diffractometer (XRD) and infrared spectroscopy (IR). It is found that the morphology of these crystals is related to the activity or fresh degree of the starting Ca–P precipitates and the added fluorine ions, but is not greatly influenced by the Ca/P ratio of the precipitates. These crystals with a Ca/P ratio between 1.67 and 1.5 show a poorly crystallized apatite structure at room temperature and a biphasic (HA+–TCP) structure at 1100°C, corresponding to their Ca/P ratio. It is demonstrated that these nonstoichiometric apatite crystals contain lattice-bound water which could play an important role in the formation of bone apatite. The similarity in morphology and composition between these needle-like crystals and the apatite crystals in bone provides a possibility to make a bone-like implant consisting of these needle-like crystals and collagen, etc.     

Rheological characterization of polypropylene filled with magnesium hydroxide

Consideration is given to the dynamic viscoelastic and shear flow properties of magnesium hydroxide-filled polypropylene, at a filler concentration of 60 wt%. Five variants of magnesium hydroxide were used, one surface-treated with magnesium stearate. The results reported illustrate the effects of filler particle size, morphology and surface coating on the rheology of the composites. The presence of magnesium hydroxide caused a significant increase in the shear viscosity of polypropylene relative to unfilled polymer, although this was much less pronounced using surface-treated filler, particularly at low shear rates. Complex viscosity and storage modulus data, obtained at very low shear rates (0.002 s^–1), demonstrated the presence of a critical shear yield stress for flow to occur, which was greatest for compositions containing uncoated fillers with small particle size. These observations are discussed in terms of structure formation between the particles. Results obtained from capillary and dynamic measurements of melt flow were found to follow the Cox-Merz rule.