乳液插层法制备丁腈橡胶-有机蒙脱土纳米复合材料的结构与性能

采用乳液插层法制备了丁腈橡胶(NBR)-有机蒙脱土(OMMT)纳米复合材料;用TEM技术对纳米复合材料的微观结构进行了表征;并研究了OMMT添加量对纳米复合材料的力学性能、耐溶剂性、耐低温性和热稳定性的影响。实验结果表明,用该法制备的NBR-OMMT纳米复合材料是一种插层型的纳米复合材料,其力学性能随OMMT添加量的增加而增强,具有优异的耐溶剂性和耐低温性。TG分析结果显示,添加30份(质量份数)OMMT时,纳米复合材料的最大降解率温度较NBR提高了约10℃,具有优异的热稳定性。     

有机蒙脱土对天然橡胶-丁腈橡胶的补强及增容作用

采用乳液法和机械混炼法制备了天然橡胶(NR)-丁腈橡胶(NBR)-有机蒙脱土(OMMT)纳米复合材料(简称纳米复合材料);用TEM和XRD技术对纳米复合材料的亚微观结构进行表征,并对纳米复合材料的表观交联密度、静态力学性能、动态力学性能和硫化热效应进行了研究。实验结果表明,纳米复合材料为剥离型纳米复合材料;添加OMMT,提高了纳米复合材料的表观交联密度和静态力学性能,使NR-NBR共混胶的动态损耗因子降低,使NR和NBR的玻璃化转变温度更为接近,起到了增容作用;OMMT的添加实现了NR和NBR两相的同步硫化。     

有机蒙脱土与MCM-41介孔分子筛的共同填加对聚丙烯基复合材料性能的影响

以纳米有机蒙脱土(OMMT)、MCM-41纳米介孔分子筛(不含模板剂)、OMMT/MCM-41混合物(m(OMMT):m(MCM-41)=1:1)为填料(增强组分),通过双螺杆挤出机制备了聚丙烯(PP)基纳米复合材料;考察了填料种类及添加量对纳米复合材料性能的影响。实验结果表明,以OMMT/MCM-41混合物为填料时,两种粒子起到了协同增强、增韧的作用;当OMMT/MCM-41混合物的添加量(以体系的总质量计)为2.0%时,PP基纳米复合材料的拉伸强度和冲击强度达到最大值,分别为45.1MPa和38.6kJ/m2,比PP分别提高了30%和53%;同时添加OMMT和MCM-41的PP基纳米复合材料的热稳定性高于单独填加OMMT或MCM-41的PP基纳米复合材料。     

纳米MoS_2催化剂的制备及其加氢脱氧性能研究

采用机械活化法,以MoO3和硫的球磨混合物作为反应物,在400～800℃氩气气氛中硫化80 min制备出纳米MoS2催化剂。采用BET,XRD,SEM,TEM方法对催化剂进行了表征,以4-甲基苯酚为模型化合物考察了纳米MoS2催化剂的加氢脱氧性能。实验结果表明,所制得的MoS2催化剂具有典型的低堆垛层状结构,这些层状结构排列成纳米片,其长度约为100 nm,厚度小于10 nm,并具有单分散性和高比表面积(83.6 m2/g左右)。当硫化温度为500℃时,纳米MoS2催化剂的活性最高,4-甲基苯酚的加氢脱氧转化率为58.2%。4-甲基苯酚的加氢脱氧反应主要按直接脱氧路径进行,随硫化温度的升高,纳米MoS2催化剂对加氢路径的选择性逐渐提高。     

纳米薄片PtSnNa/MFI催化剂的制备及其丙烷脱氢性能研究

采用水热合成法和浸渍法制备了不同硅铝比的纳米薄片负载型PtSnNa/MFI系列分子筛催化剂,并考察了纳米薄片催化剂的丙烷脱氢性能。采用XRD、SEM、TEM、~(27)Al MAS NMR、N_2吸附-脱附、FTIR等方法对催化剂的形貌、孔结构及物性参数等进行了表征。表征结果显示,催化剂具有纳米薄片交叉构成的球形形貌和介孔结构,纳米薄片的厚度为20～40nm,催化剂中的Pt分散于纳米薄片分子筛表面。实验结果表明,硅铝比为100和500的MFI分子筛制备的PtSnNa/MFI-100和PtSnNa/MFI-500催化剂在丙烷脱氢反应中都表现出较好的催化性能,在反应温度为600℃、丙烷的重时空速为3 h~(-1)、常压的条件下反应40 h时,丙烷转化率约为40%,丙烯选择性约为94%。     

纳米晶氧化铜的制备及其催化苯酚氧化性能

采用沉淀法制备了纳米晶氧化铜催化剂,通过XRD、TEM及N2吸附-脱附法对纳米晶氧化铜催化剂的微观结构进行了表征。表征结果显示,制备的纳米晶氧化铜的平均粒径为8.5 nm,比表面积为56.2 m2/g。研究了纳米晶氧化铜催化氧化苯酚的性能,同时对反应条件进行了优化。实验结果表明,自制的纳米晶氧化铜催化剂具有优良的催化性能,反应条件(如催化剂用量、抗坏血酸用量、溶剂中醋酸含量及反应温度)对苯二酚收率有显著影响。在苯酚浓度1.28 mol/L、催化剂用量0.572mol/L、抗坏血酸用量0.796 mol/L、20%(φ)醋酸水溶液(50 mL)为溶剂、氧气流量70~80 mL/min、反应温度308 K的优化条件下反应90 min,苯二酚收率达14.90%。     

高分散纳米0价铁/蒙脱土催化材料的制备

采用常温下KBH4还原铁柱撑蒙脱土,研究制备高分散纳米单质铁/蒙脱土复合材料.实验首先制成铁柱撑蒙脱土,然后用0.5 mol/L的KBH4溶液还原来制备产物,并采用XRD、EDS、SEM、TEM对产物进行了表征.XRD结果表明,经柱撑作用后,蒙脱土的层间距由1.26 nm扩大到1.57 nm;KBH4还原后在2θ=44.75°有铁单质的特征衍射峰,层间粒子尺寸收缩;EDS结果显示铁含量增加且铁颗粒不含B元素;TEM表明,铁粒子高度分散且粒径分布窄,介于30～40nm,研究证实所得材料为纳米0价铁/蒙脱土复合材料.     

天然橡胶机械混炼插层有机蒙脱土过程的研究

用机械混炼法制备了天然橡胶(NR)-有机蒙脱土(HMT)纳米复合材料。采用X射线衍射(XRD)和透射电子显微镜研究了NR分子链插层HMT片层的层间距和形态。对NR-HMT纳米复合材料混炼和硫化过程中的胶料进行了XRD测试,研究了NR对HMT的插层过程。实验结果表明,NR能插入到HMT的层间,得到NR-HMT纳米复合材料,HMT的层间距从2.54nm增大到4.55nm以上,HMT填充量越小,层间距越大。NR分子链在混炼、焦烧、硫化过程中都能对HMT进行插层;部分HMT的层间距在整个加工过程中不断增大;部分HMT的层间距在混炼时减小到1.43nm,而在后续的加工过程中又增大。     

一步法制备纳米层状钒磷氧催化剂

以多聚磷酸为替代磷源、硝酸铋和二甲基亚砜为助剂,采用一步法制备了纳米层状钒磷氧(VPO)催化剂,采用XRD,SEM,XPS,FTIR,BET等方法对纳米层状VPO催化剂进行了表征,并对其催化正丁烷氧化制顺酐反应的性能进行了评价。表征结果显示,纳米层状VPO、催化剂的微观形貌呈玫瑰花苞状,花苞是由大量片层晶体堆积而成,花苞直径约为5～7μm,片层晶体厚度约为50～80nm;催化剂表面成分主要是(VO)_2P_2O_7。实验结果表明,纳米层状VPO催化剂的催化性能良好,在正丁烷与空气体积比1.5:98.5、气态空速1500 h~(-1)、反应温度400℃、反应时间72h的条件下,正丁烷转化率为79.4%,顺酐选择性为68.8%,顺酐收率为54.63%。     

Ru-Rh/AC催化对苯二酚选择性加氢制备1,4-环己二醇

采用浸渍法制备了负载在活性炭(AC)上的Ru-Rh/AC双金属催化剂,通过ICP-AES,TEM,XRD方法对Ru-Rh/AC催化剂进行了表征;将Ru-Rh/AC催化剂用于对苯二酚选择性加氢制备1,4-环己二醇的反应,系统考察了溶剂、反应温度、反应压力和催化剂用量对该反应的影响。表征结果显示,活性组分在AC载体表面形成了高分散的粒径为2～5 nm的合金颗粒。实验结果表明,优化的反应条件为:以异丙醇为溶剂、催化剂中Ru-Rh金属与对苯二酚摩尔比为0.005、反应温度80℃、反应压力1.0 MPa。在此条件下反应1 h,对苯二酚转化率为100%,目的产物1,4-环己二醇的选择性为95.5%。Ru-Rh/AC双金属催化剂具有较好的稳定性。     

水性聚氨酯/硅烷蒙脱土纳米复合材料的制备与性能

用硅烷偶联剂修饰蒙脱土,制备了水性聚氨酯/硅烷蒙脱土纳米复合材料。傅里叶变换红外光谱、X射线衍射和透射电镜表征结果表明,硅烷偶联剂对蒙脱土的表面进行了有效的修饰,合成水性聚氨酯的各单体在蒙脱土层间聚合,使片层间距达到了5.19nm。热重分析和力学测试表明,水性聚氨酯/硅烷蒙脱土纳米复合材料比纯水性聚氨酯具有更优异的热性能,当硅烷蒙脱土的质量分数为2%时,拉伸强度和断裂伸长率分别提高了56.4%和40.0%。     

蒙脱土-有机硅复合改性硅烷化聚氨酯密封胶

采用2,4-甲苯二异氰酸酯、聚醚多元醇、蒙脱土、有机硅(α,ω-二羟基聚二甲基硅氧烷)和硅烷偶联剂为原料,制备了有机蒙脱土/聚醚多元醇复合物(OMMT/330N)-有机硅复合改性的硅烷化聚氨酯(SPU)密封胶。通过广角X射线衍射、透射电子显微镜和傅里叶变换红外光谱手段表征了蒙脱土在复合材料中的分散情况,表征结果显示,有机蒙脱土以平均层间距不小于4.12nm的宽分布分散在SPU基体中。同时对密封胶的力学性能进行测试,测试结果表明,经OMMT/330N-有机硅复合改性的SPU密封胶具有性能互补效果,当添加质量分数为5%(基于330N)的OMMT和8%的有机硅时,复合改性的SPU密封胶的拉伸强度和断裂伸长率比纯SPU密封胶提高了65.8%和71.6%。     

Preparation,characterization and evaluation of polybenzoxazine thermoset/clay nanocomposites for metal coating

A series of polybenzoxazine-clay nanocomposites with various organoclay contents (3, 5, 10, and 20 wt%) were prepared by the one-shot procedure. from organo-montmorillonite (OMMT) and bifunctional benzoxazine, namely, bis-(3-dodecyel-3,4-dihydro-2H-1,3-benzoxazine) isopropane (B-dod). OMMTs were prepared by modification of Na-MMT with different ammonium salts of amines such as tyramine (Tyr), amino lauric acid (ALA) and N,N-dimethyl stearyl amine (DMS). Transmission electron microscope (TEM), X-ray diffraction (XRD) and infrared measurements (FTIR) were used to examine the structure and modification of OMMTs. The morphology of polybenzoxazine nanocomposites (B-dod/Tyr-MMT, B-dod/ALA-MMT, B-dod/DMS-MMT) was investigated by X-ray and TEM analyses. The X-ray analysis and TEM photos indicated that organoclay was exfoliated into polybenzoxazine matrix even at the highest organoclay loading (20%). Mechanical properties (viz, adhesion on metallic substrate, scratch hardness, tensile modulus, and elongation at break) of the prepared nanocomposites were measured. The tensile properties of prepared samples were examined; as the content of modified clay was increased, the tensile modulus increased; however, the elongation at break decreased. In addition, the optimum adhesion and scratch hardness values of the prepared nanocomposites were increased more than the neat resin, also, thermogravimetric analysis has the same manner. Therefore, the prepared nanocomposite materials could be successfully used for metal coatings.     

Electrophysical characteristics of polyurethane/organo-bentonite nanocomposites

Modification of the Egyptian Bentonite (EB) was carried out using organo-modifier namely; octadecylamine ODA. Before the modification, the cation exchange capacity (CEC) of the EB was measured, also it was purified from different impurities using HCl and distilled water. The Organo-bentonite OB was characterized using IR, XRD, and TEM. PU/ODA-B nanocomposites were prepared by in situ polymerization then characterized by XRD and TEM. An amount of ODA-B ranging from 0.25% up to 5% by weight was added to the polyol component of the resin before mixing with toluene diisocynate TDI. TEM showed that the nanocomposites achieved good dispersion in the polyurethane matrix. The mechanical, swelling and electrical properties of the nanocomposites were measured. The results indicate that the tensile strength of all the nanocomposites enhanced with the addition of OB compared with the pure PU. The crosslink density of the nanocomposites increases with increasing the content of OB. The Pool–Frenckel conduction mechanism predominates for all the nanocomposite samples and the blank one.     

Elimination of Safranin-O and a binary mixture of Safranin-O and methylene blue from water by adsorption on magnetite/Ag nanocomposite

The present research aimed at the removal of Safranin-O (Saf-O) dye and a binary mixture of Saf-O and methylene blue (MB) from an aqueous solution by adsorption onto the surface of magnetite/Ag nanocomposite to find a feasible and an effective route for cleaning the wastewater from these dyes. The nanocomposite was synthesized by the co-precipitation method in the presence of nanosilver which in turn was prepared by the reduction of Ag⁺ by sodium citrate. The nanocomposite was characterized by FT-IR, XRD, SEM, EDX, and TEM techniques. The adsorption of the single Saf-O and its binary mixture with MB was studied under the effect of several experimental conditions. These conditions were the initial concentration of dyes, nanocomposite dose, Ag to magnetite ratio, pH of the medium, presence of salt, time of contact, and solution temperature. The adsorption process followed pseudo-second-order kinetics The Langmuir and Freundlich adsorption isotherms were applied and the data were best fitted with the Langmuir model confirming monolayer adsorption of dyes. The maximum adsorption capacity was 46.3 mg/g for the single Saf-O and (38.46 + 34.97) for the (Saf-O + MB) binary mixture at 30 °C. The adsorption process was spontaneous and endothermic. The recyclability of the magnetite/Ag nanocomposite was confirmed through five reusable cycles where it can be considered a promising adsorbent for wastewater treatment from dyes.     

HPA/MCM-48催化剂上四氢呋喃开环聚合

根据MCM－48可具有纳米尺寸的孔径和孔壁的独特的结构特征，提出了以这样的MCM－48作为无机基体，形成纳米网络粒子的设想，并设计了将催化活性中心引入MCM－48孔内，在孔内原位聚合形成纳米网络粒子的方法，以HPA为催化活性中心，在MCM－48孔内进行了四氢呋喃的原位环聚合反应，通过对比聚合反应前后HPA／MCM－48的FT－IR谱图，证实了这一原位开环聚合的发生。     

The Effect of Nanoclay on Rheological Properties and Storage Stability of SBS-Modified Bitumen

Abstract

Linear and branched grades of styrene-butadiene-styrene (SBS) triblock copolymer are commonly used for modifying physical, mechanical, and rheological properties of bitumen. Because bitumen and SBS are incompatible, SBS-modified bitumen is not storage stable at elevated temperatures. Incompatibility of branched SBS is greater than linear SBS. To obtain greater compatibility between SBS and bitumen, organophilic montmorillonite/SBS-modified bitumen mixtures, prepared by melt intercalated blending, were used. Results showed that the presence of nanoclay could improve the storage stability, aging, and high-temperature performance of polymer-modified bitumen (PMB) significantly. Of course, this effect can be seen by proper dispersion of organophilic montmorillonite (OMMT) in SBS and obtaining a homogenous blend, which is calleed an exfoliated structure. The structure of OMMT/SBS/bitumen blend was characterized by X-ray diffraction (XRD).