CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLYPROPYLENE FILLED WITH SiO_2 NANOPARTICLES

Oleic acid （OA）-modified SiO2 （OA-m-SiO2） nanoparticles were prepared using surface modification method. Infrared spectroscopy （IR） was used to investigate the structure of the OA-m-SiO2 nanoparticles, and the result showed that OA attached onto the surface of SiO2 nanoparticles through esterification. Effect of OA concentration on the dispersion stability of OA-m-SiO2 in heptane was also studied, and the result indicated that OA-m-SiO2 nanoparticles were dispersed in heptane more stably than the unmodified ones. OA-m-SiO2 nanoparticles can also be dispersed in polypropylene （PP） matrix in nano-scale. The effect of OA-m-SiO2 on crystallization of PP was studied by means of DSC. It was found that the introduction of OA-m-SiO2 resulted in significant increase in the crystallization temperature, crystallization degree and crystallization rate of PP, and OA-m-SiO2 could effectively induce the formation of β-crystal PP. Effect of OA-m-SiO2 content on mechanical properties of PP/OA-m-SiO2 nanocomposites was also studied. The results show that OA-m-SiO2 can significantly improve the mechanical properties of PP.

Nafion/SiO_2 Nanocomposites:High Potential Catalysts for Alkylation of Benzene with Linear C_9-C_(13) Alkenes

High surface area Nafion/SiO2 nanocomposites with nano-sized Nafion resin particles entrapped and dispersed within the highly porous silica matrix exhibited significantly enhanced activity, high selectivity and long-term stability for the alkylation of benzene with linear C9-C13 alkenes owing to the increased accessibility of Nafion resin-based acid sites to reactants.

Preparation and upconversion luminescence properties of LaF_3:Yb^(3 +),Er^(3 +) /SiO_2 nanocomposites with core /shell structure

LaF^3＋ Yb^3＋ , Er^3＋ nanoparticles were successfully synthesized using solvothermal treatment, and LaF^3＋ Yb^3＋ , Er^3＋/SiO2 core/shell nanoparticles were also prepared with reverse microemulsion technique. The crystal structure, morphology and photoluminescence properties of as-prepared core/shell nanoparticles were in- vestigated by X-ray diffraction, transmission electron microscopy and fluorescence spectrophotometer. The re- sults showed thatLaF^3＋ Yb^3＋ , Er^3＋ nanoparticles are of hexagonal structure and SiO2 shell is amorphous. The size ofLaF^3＋ Yb^3＋ , Er^3＋. nanoparticles is 13 nm and the LaF^3＋ Yb^3＋ , Er^3＋/SiO2 nanoparticles present clearly a core/shell structure with 12 nm shell thickness. The solubility of LaF^3＋ Yb^3＋ , Er^3＋ nanocrystals in water and the biocompatibility are both improved by the SiO2 shell. The upconversion luminescence spectra suggested that the SiO~ shell has small effect on the upconversion luminescence properties of the LaF^3＋ Yb^3＋ , Er^3＋ nanocrys- tals. The core/shell structure LaF^3＋ Yb^3＋ , Er^3＋ /SiO2. nanopartlcles are expected to be used in biological appli- cations.

Benzylation of Aromatic Compounds with Benzyl Chloride Catalyzed by Nafion/SiO_2 Nanocomposite Catalyst

In the presence of Nafion/SiO2 nanocomposite catalyst, the benzylation of aromatic compounds with benzyl chloride proceeded to afford diphenylmethane derivatives in high yields. The catalyst showed high catalytic activity not only for electron-rich aromatic compounds, but also for electron-poor aromatic compounds. Under identical conditions, the self-benzylation of benzyl chloride, and dibenzylation and/or multi-benzylation of aromatic compounds were negligible.

纳米SiO_2增强增韧聚丙烯的研究

通过熔融共混法制备了SiO2 分散很好的聚丙烯 /纳米SiO2 复合材料。力学性能测试结果表明 ,当使用 2份纳米SiO2 时 ,聚丙烯 /纳米SiO2 复合材料的力学性能最优 :与纯PP相比 ,V形缺口冲击强度提高了 90 %,弯曲强度提高了 2 3%,拉伸强度提高了 5 %;成型收缩率增大 ,这是由于大量分散于PP中的超细SiO2 使PP晶体变小引起的。

纳米SiO_2改性PP的结晶结构与特性研究

采用偏光显微镜观察和研究了三种不同表面处理的纳米SiO2 改性PP的结晶结构 ,并通过DSC分析方法 ,研究了它们的结晶特性。结果表明 :纳米SiO2 在PP中具有成核剂作用 ,PP以异相成核方式结晶 ,使PP的结晶温度提高 ,结晶速率增大 ,球晶颗粒变得细小而均匀 ,但基本不影响PP的结晶度和熔点。纳米SiO2 在PP中的粒度越小 ,分散越均匀 ,或适当提高其含量 ,上述作用越明显。纳米SiO2 的表面处理对PP/纳米SiO2 材料的结晶结构和特性影响很大 ,其中经表面偶联剂加分散剂处理的纳米SiO2 -AB对PP结晶的上述影响最为明显。

PPy/SiO_2纳米复合材料的合成与导电性能

以乙醚为反应介质，用化学方法合成了聚吡咯（ＰＰｙ／ＳｉＯ２）纳米复合材料。利用红外光谱、四探针技术和透射电镜表征了这些材料的组成、结构和导电性能。结果表明，载流子在ＰＰｙ分子链之间和ＰＰｙ聚集体之间有显著的传导性。

在无机SiO_2纳米粒子存在下的苯丙乳液共聚合

研究了在无机 Si O2 纳米粒子存在下的苯丙乳液共聚合 .选择了能使苯丙乳液稳定存在的乳化剂体系 ,研究了温度和 Si O2 的加入对聚合过程转化率的影响 ,结果表明 ,Si O2 的加入对聚合过程有阻聚作用 ,使单体的转化率降低 .SEM照片证明 Si O2 粒子已经进入苯丙乳液粒子中 ,而且 Si O2 的加入对乳液制成的膜断面形态有一定影响 .实验发现在无机 Si O2 纳米粒子存在下 ,苯丙乳液共聚合时有较多残渣出现 ,对此通过改进乳液聚合进行了有效地改善 .

动态硫化法PP/EPDM/纳米SiO_2双重粒子协同增韧改性研究

以三元乙丙橡胶 (EPDM)作弹性粒子 ,以纳米SiO2 作刚性粒子 ,通过动态硫化方法制备了PP/EPDM/纳米SiO2 三元改性材料 ,并采用力学性能测试、动态力学试验、DSC分析和偏光显微镜观察等方法 ,研究了该材料的结构与性能。结果表明 ,纳米SiO2 与EPDM对PP具有协同增韧和增强效应 ,这种效应与 2种粒子的浓度比相关 ,当纳米SiO2 质量分数为 3 %、EPDM质量分数为 1 0 %时 ,协同作用最明显。 2种粒子使PP出现较大的低温损耗模量峰 (E″)和内耗峰 (tanδ) ,并具有成核作用 ,使PP结晶温度提高 ,结晶速率加快 ,形成的球晶细小而均匀 ,并同时提高结晶度和熔点。

纳米SiO_2改性聚丙烯薄膜的制备及力学性能研究

为了提高聚丙烯薄膜的力学性能,研制了一种纳米Si O2改性剂,采用熔融共混法将纳米改性剂填充到聚丙烯树脂中,流延、双向拉伸制备聚丙烯/纳米Si O2复合薄膜,并对其拉伸性能、穿刺性能等力学性能及阻隔性能(透湿)进行测试。结果表明,当纳米Si O2质量分数为0.8%时,改性薄膜的拉伸强度较未改性薄膜提高18%,杨氏模量提高58%,断裂伸长率提高65%。

聚N-异丙基丙烯酰胺/SiO_2纳米复合水凝胶的制备及性能

用一种简便、通用的方法,以N-异丙基丙烯酰胺为单体,以修饰二氧化硅为交联剂和增强剂,制备出一种具有较高机械强度和良好温度响应性能的聚N-异丙基丙烯酰胺/SiO_2PNIPAm/m-SiO_2纳米复合水凝胶.采用TEM、SEM、傅里叶变换红外光谱、万能实验机和差示扫描量热法,对水凝胶的结构、机械性能和热力学性能,进行了分析、测试和表征.研究结果表明:该复合水凝胶具有孔径均匀分布的三维网状结构(孔径约1μm)、高的机械强度(压缩强度可以达到8MPa)和良好的韧性,并在35℃左右具有明显的相转变行为(去溶胀性能).

Synthesis of Fe_3O_4-coated silica aerogel nanocomposites

Fe3O4:SiO2 nanocomposite powders were synthesized by a two-step process,which included the precipitation of FeCl2 and FeCl3 and the gelation of silicic acid solution derived from water glass.At first,Fe3O4 nanoparticles having a crystallite size of 20 nm were obtained by controlling the ratio of Fe(II) and Fe(III) precursors.In the second step,Fe3O4 particles were embedded in SiO2 matrix by the hydrolysis and subsequent condensation of the silicic acid solution containing Fe3O4 particles.It was found that the Fe3O4 nanoparticles homogenously disperse in the SiO2 matrix.The Fe3O4:SiO2 nanocomposite exhibited an enhanced thermal stability against oxidation compared with pure Fe3O4.FT-IR analysis indicates the presence of the Si-O-Fe bond in the Fe3O4:SiO2 (1:10,mole fraction) nanocomposite.

Sol-Gel Preparation of Nanoscale TiO₂/SiO₂Composite for Eliminating of Con Red Azo Dye

A new anatase/SiO2 nanocomposite was synthesized by sol-gel method at room temperature using titanium tetrachloride and tetraethylorthosilicate as raw materials. Characterization of the product was carried out by means of X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) specific surface areas, Thermogravimetry analysis (TGA), Fourier transform infrared (FT-IR), and UV-vis absorption spectroscopy. Thermal phase transformation studies of composite were carried out up to 1100°C which showed the establishment of anatase TiO2 phase. The presence of some tetrahedral coordination of TiO2 species in SiO2 matrix was confirmed by UV-Vis study. The produced TiO2/SiO2 nanocomposite has good photocatalytic properties due to its anatase phase, existence of tetrahedral coordination of TiO2 in the SiO2 matrix and very large surface area. Furthermore, the synthesized anatase/SiO2 shows significant adsorption ability towards Congo Red (CR) azo dye in comparison with the pure commercial TiO2 which is known as Degussa, P25.

Thermal Stability and Crystallinity Study of Polystyrene/SiO2 Nano-Composites Synthesis via Microwave-Assisted In Situ Polymerization

Serials of polystyrene/SiO2 Nano composites (PS/SiO2) with different content of inorganic fillers were successfully prepared by the in situ bulk radical polymerization of styrene under microwave irradiation. The effect of the amount of Nano SiO2 on the properties of the PS/SiO2 Nanocomposites along with the average relative molecular masses (Mn, Mz and Mw) was investigated by thermal analysis and X-Ray Diffraction (XRD). Their structural model was proposed on the basis of the Optical Microscopy, FTIR (Fourier Transform Infrared) analysis, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and X-Ray Diffraction (XRD). The dispersion of nanoparticles in Polystyrene is observed in the magnified image. The effect of microwave irradiation power on molecular weight of polystyrene was also studied. It was found that, the microwave assisted reaction needs less time as compare to conventional polymerization and found to be in between 10 to 15 min.

Synthesis of silica/metatitanic acid nanocomposite and evaluation of its catalytic performance for aquathermolysis reaction of extra-heavy crude oil

A lipophilic silica/metatitantic acid（denoted as Si O2/H2 TiO 3） nanocomposite was synthesized by hydrothermal reaction with surface-modified Si O2 as the lipophilic carrier. As-synthesized Si O2/H2 TiO 3nanocomposite was used as a catalyst to promote the aquathermolysis reaction of extra-heavy crude oil thereby facilitating the recovering from the deep reservoirs at lowered temperature. The catalytic performance of the as-synthesized Si O2/H2 TiO 3catalyst for the aquathermolysis reaction of the heavy oil at a moderate temperature of 150 °C was evaluated in relation to the structural characterizations by TEM,FTIR,XRD and FESEM as well as the determination of the specific surface area by N2adsorption–desorption method. Findings indicate that as-synthesized Si O2/H2 TiO 3nanocomposite exhibits an average size of about 20 nm as well as good lipophilicity and dispersibility in various organic solvents; and it shows good catalytic performance for the aquathermolysis reaction of the extra-heavy oil extracted from Shengli Oilfield of China. Namely,the assynthesized Si O2/H2 TiO 3catalyst is capable of significantly reducing the viscosity of the tested heavy oil from58,000 c P to 16,000 c P（referring to a viscosity reduction rate of 72.41%） at a mass fraction of 0.5%,a reaction temperature of 150 °C and a reaction time of 36 h,showing potential application in downhole upgrading heavy crude oils.

Concentration and annealing effect on PL properties of sol-gel derived SiO_2-Y_2O_3:Eu^(3+) nanocomposites

An improved sol-gel method was employed to prepare Eu3+ ions doped SiO2-Y2O3 nanocomposites.Systematic study was carried out on the effect of post-annealing treatment on photoluminescence(PL) properties of the samples under various europium ions doping concentrations.X-ray diffraction(XRD) patterns indicated that the samples showed an amorphous matrix structure,and the scanning electron microscopy(SEM) pictures showed that the samples presented a nano size(from 21 to 42 nm) granular-stack structure after hi...

Interface interaction and inter-osmosis effect of Fe_x (SiO_2)_(1-x) nanocomposite materials on magnetic properties

Fe_x(SiC_2 )_(1 - x) nanocomposites prepared by using mechanical alloying method were reported. The mi-crostructure character and magnetic properties of Fex (SiO_2) 1 - x nanocomposite samples with different Fe content and different ball milling time were studied by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy, and Faraday magnetic balance in a wide temperature range. The results indicate that the mi-crostructure and magnetic properties are closely related to ball milling time and Fe content. When Fe content is less than 20 wt% , the sample after 80-h ball milling has very complex microstructure. Small α-Fe grains and Fe cluster are implanted in SiO2 matrix. And there are not only isolated α-Fe granular and Fe cluster, but also nanometer scaled sandwich network-like structure. Fex (SiO_2) 1 - x nanocomposite samples display a rich variety of physical and chemical properties as a result of their unique nanostructure, strong interface interaction and inter-osmosis effect in Fe-SiO_2 boundaries, and the grain size effect.

利用聚合物乳液合成聚甲基丙烯酸甲酯/二氧化硅纳米杂化材料

通过正硅酸乙酯分别在聚甲基丙烯酸甲酯乳液和四氢呋喃溶液中的溶胶 -凝胶反应制备出不同的聚甲基丙烯酸甲酯 /二氧化硅复合材料 .利用扫描电镜、透射电镜、差热分析和热失重对试样进行了分析 .结果表明 ,利用聚合物乳液可以获得纳米分散的聚甲基丙烯酸甲酯 /二氧化硅复合材料 ,并且在某种程度上其分散尺度小于利用聚合物溶液获得的复合材料 .同时 ,利用聚合物乳液来制备聚甲基丙烯酸甲酯

纳米材料在硅橡胶改性中的应用

在 2 6篇文献的基础上 ,综述了 Al2 O3、Ca CO3、Ti O2 、Si O2 等纳米粒子对硅橡胶的力学性能、阻隔性能、抗老化性能、电气性能等方面的影响。评价了硅橡胶纳米复合材料的工业价值 。