镀层表面形貌的分形维数定量表征

为了定量表征镀层表面的形貌特征,应用当代非线性科学新理论--分形几何学方法,研究了几种镀层的表面形貌,用表面分形维数定量表征了其表面形貌特征.结果表明,用像素点覆盖法计算的表面分形维数介于1～2之间,覆盖法计算的则介于2～3之间,后者较接近表面形貌的真实分形维数;两者计算的相关系教都大于0.99,说明镀层具有分形结构.该方法可为进一步研究镀层表面形貌及优化电镀工艺参数提供一种新的定量依据.     

人造骨料表面改性改善混凝土界面过渡区性能研究

针对混凝土用人造骨料表面疏松多孔和水泥浆体结合能力不足的问题,提出包覆和表面疏水特性修饰的新方法处理人造骨料。试验将不同质量分数的硅烷偶联剂溶液与有机硅树脂联合改性应用于碳化养护的人造骨料,研究改性方法对人造骨料吸水率、颗粒强度、骨料-水泥砂浆黏结强度等性能的影响规律,利用细观/微观测试分析方法表征改性前后人造骨料的微观结构以及人造骨料与水泥砂浆的界面形貌。结果表明,较单一使用化学溶液改性人造骨料,联合改性方法可显著优化人造骨料的表面微观结构,提升骨料性能,骨料吸水率可降低至1.74%。当硅烷偶联剂质量分数为5%时,人造骨料表面形成厚度合适的改性层,人造骨料与水泥砂浆的结合程度显著提升。     

金属垫片密封表面形貌的分形表征

引言 金属垫片密封结构常见于石油、化工、核能等装置中,广泛应用于高温、高压及强腐蚀介质等操作条件恶劣、密封要求高、一般的垫片无法满足要求的场合.     

基于显微边界形貌分形特征的耐火材料侵蚀维数研究

通过对侵蚀残砖的显微边界形貌研究发现 :耐火材料的抗侵蚀性能和基于显微边界形貌分形特征的分形维数存在良好的线性关系。根据分形维数的定义和含义 ,作者提出了一种基于分形理论的耐火材料侵蚀维数Rf (Refractoryfractal)的概念和抗侵蚀分类建议。根据耐火材料的使用经验和实绩而定义的Rf =[1.0 ,1.0～ 1.15 ,1.15～ 1.2 0 ,≥ 1.2 ]数值范围 ,可以用于耐火材料抗侵蚀性能的评判、分类 ,并且可用于设计选型和编制相对应的耐火材料的残余安全厚度的日常维护规程等     

基于分形维数对纳米二氧化硅颗粒分散性的量化表征研究

开发了一种基于分形维数来表征纳米颗粒团聚行为的方法,通过对纳米SiO₂颗粒的透射电子显微镜的图片进行分析,并借助冷冻切片技术对硅橡胶中的SiO₂分布状态进行观测和分形维数的计算,探究了分形维数与吸油值、表面羟基数、力学性能等的关系。结果表明：纳米颗粒的团聚程度越大其分形维数越大;通过对纳米SiO₂补强硅橡胶的超薄切片的分形维数的计算可知,在聚合物中的纳米颗粒的团聚也呈现相同的规律,即分形维数越大团聚程度越大;此外,分形维数越大,纳米SiO₂的吸油值越小,表面羟基数越少,硅橡胶片的拉伸强度、撕裂强度及邵尔A硬度则越大。     

n-Al2O3/Ni-Co纳米复合电刷镀层表面形貌的分形维数研究

采用电刷镀技术,在45钢上获得了n-Al2O3/Ni-Co纳米复合电刷镀层.研究了镀液中纳米颗粒加入量对镀层的表面形貌和显微硬度的影响,并利用盒维数的计算方法,计算了表面形貌的分形维数,初步建立了表面形貌的分形维数与镀层显微硬度之间的关系.对比分析表明:随着镀液中纳米颗粒含量的增加,镀层表面形貌的分形维数先减小后增大,镀层的显微硬度则先增大后减小,但都在镀液中纳米颗粒加入量为20g/L时达到最值,即镀层表面形貌的分形维数与其显微硬度有负相关的对应关系.     

n-Al_2O_3/Ni-Co纳米复合电刷镀层表面形貌的分形维数研究

采用电刷镀技术,在45钢上获得了n-Al2O3/Ni–Co纳米复合电刷镀层。研究了镀液中纳米颗粒加入量对镀层的表面形貌和显微硬度的影响,并利用盒维数的计算方法,计算了表面形貌的分形维数,初步建立了表面形貌的分形维数与镀层显微硬度之间的关系。对比分析表明:随着镀液中纳米颗粒含量的增加,镀层表面形貌的分形维数先减小后增大,镀层的显微硬度则先增大后减小,但都在镀液中纳米颗粒加入量为20g/L时达到最值,即镀层表面形貌的分形维数与其显微硬度有负相关的对应关系。     

沸石分子筛表面分形维数与孔性质的关联分析

为了研究模板材料对沸石分子筛表面形貌和孔结构性质的影响以及在焙烧除模板材料过程中分子筛表面复杂程度和孔道分布的变化,分别采用X射线衍射和氮气物理吸附-脱附对沸石分子筛进行表征,基于分形学理论引入分形维数及其计算,并将计算结果与分析结果进行对比讨论。结果表明,分形维数与分子筛表面的复杂程度密切相关,分子筛表面越复杂、沟壑越多,分形维数越大,反之则越小;模板材料影响分子筛不同指数晶面的生长速率和生长取向,进而影响分子筛的外观形貌和孔道结构性质,在焙烧除模板材料后,分子筛表面部分较大孔道发生塌陷,致使整体结构趋于平整化,分形维数减小。     

生物质焦分形维数计算

采用压汞法的实验数据,计算两种分形模型下生物质焦样的分形维数。其中根据Menger海绵模型计算得到的分形维数Dm的值在2．7～3．1之间,基于热力学关系的分形模型计算得到的分形维数Dr的值在2．7～2．9之间。分析认为第二种模型更好的描述了焦样的孔隙结构,Dr的值比Dm的值更为合理。实验结果表明,分形维数与生物质种类有关,树叶焦样的分形维数整体上大于稻壳焦样的分形维数。生物质焦样的平均孔径与分形维数有关。总的来看,同一生物质焦样的分形维数随着平均孔径的增大而减小。     

基于分形理论的橡胶复合材料磨耗表面形貌表征

利用橡胶高温磨耗试验机,进行不同温度、角度、负荷及路面条件下的高温磨耗试验,获得具有不同形貌的橡胶磨耗试样。借助3D测量显微镜采集橡胶试样表面形貌图像并进行表征,对橡胶表面磨耗形貌图像进行黑白二值化处理,利用分形理论建立多重分形谱分析模型,定量分析不同试验条件下橡胶试样表面磨耗形貌,定性描述表面磨耗形貌分布特点。研究结果表明,橡胶复合材料磨耗表面形貌具有明显的分形特征,橡胶磨耗性能(磨耗量)随着温度、角度、负荷和路面粗糙度增大而增大。     

再生集料及再生混凝土界面过渡区研究进展

再生集料及界面过渡区的性质对再生混凝土性能有重要影响.基于国内外再生混凝土的研究现状,分析了再生集料性质与界面过渡区的微观结构对再生混凝土物理力学性能的影响,总结了再生混凝土性能的改善措施.根据再生混凝土现阶段存在问题,提出今后应注重再生集料加工工艺优化、再生集料分级评估、界面过渡区微观结构及再生混凝土耐久性等方面的研究.     

Fractal Dimension Analysis of Flocs in Inline Coagulation-Microfiltration of Natural Organic Matter (NOM)

2D fractal dimension analysis of inline-coagulation (IC) flocs in microfiltration of NOM using power-law relationship and box-counting was done. Different process conditions represented by two types of coagulants (PIX and PAX) at four different hydraulic gradients (G-values of 4, 31, 98, and 300 s^?1) were tested. Fractal dimensions of the flocs formed under the varying process conditions were found to be different. Overall NOM removal was found to be similar for all cases; however, the membrane filtration and fouling phenomenon observed were affected by the process conditions. This study has investigated the relationships between fractal dimensions, aggregate properties, and membrane fouling behavior observed. In general, PIX resulted in higher particle concentrations and the more irregular floc shapes resulted in high irreversible fouling, lower specific cake resistance, and a more compressible cake layer. In contrast, PAX resulted in lower particle concentrations and the more regular floc shapes resulted in a more reversible fouling, higher specific cake resistance and a less compressible cake layer. The fractal dimensions properties were found to be complementary for the analysis of membrane and cake resistances and can be useful tools in membrane fouling elucidation and minimization.     

轻集料混凝土界面区形成与作用机理研究进展

轻集料混凝土中界面区的组成、结构与性能是决定其性能的关键.针对轻集料混凝土界面区的性能和特点,概括了轻集料混凝土界面区的微观结构特征和相关模型,分析了轻集料混凝土界面区的形成机理,综述了轻集料混凝土界面区对混凝土力学、耐久性能以及体积稳定性能的影响,总结了轻集料混凝土界面区研究中存在的不足和值得深入研究的方向,为轻集料混凝土界面区研究提供参考.     

Synthesis, Characterization and Surface Properties of Cross-linked Polyurethane Dispersions Modified by Organosiloxane

A series of cross-linked polyether-polyester polyurethane dispersions modified with organosiloxane were prepared based on hydroxyl-terminated polydimethylsiloxane (HTPS) as hydrophobic component and 3-aminopropyl-triethoxysilane (APTS) as cross-linker as well as a bridge between polyurethane (PU) and polysiloxane (PSIL). It was discovered that polydimethylsiloxane segments were incorporated into PU chains chemically and organosiloxane was preferentially oriented toward the surface layer of the film by making a comparison of attenuated total reflection (ATR) spectra between the copolymer and the blend of PU and PSIL, which was further confirmed by investigation of electron spectroscopy for chemical analysis (ESCA). The relationships between surface properties of the film formed from polyurethane dispersion and organosiloxane content were also studied. The results showed that water contact angle of the film increased with the increase of organosiloxane content. Interestingly, it was also found that water contact angle of PUS film increased firstly and then decreased when film-forming temperature varied from 25℃ to 55℃.     

Surface Tension in Polymer Blends of Isotactic Poly(propylene) and Atactic Polystyrene

The surface tension of atactic polystyrene (PS), isotactic poly(propylene) (PP) and PS/PP‐blends, and additionally the interfacial tension between PP/PS have been measured in the temperature range between 200 and 280°C using the pendant drop method. Within the temperature range studied, the surface tension decreased linearly with increasing temperature for all systems whereas the surface tension of neat PP is approximately 7 mN/m smaller than the value of PS. The interfacial tension between PS and PP is in the range of approximately 4 mN/m and this indicates a strong incompatibility. It results a heterogeneous PP/PS blend morphology. A significant increase of the surface tension of the blends as a function of composition is observed only when the PS content exceeds 60 wt.‐%. Furthermore, microscopic observations indicate that even if the bulk matrix material is PS, a thin layer of PP can be detected by atomic force microscopy on the droplet surface used for surface tension measurements.     

钠-萘络合物对聚氯代对二甲苯薄膜的表面改性机理研究

采用钠-萘络合物对聚氯代对二甲苯薄膜进行表面改性,通过测试接触角研究了薄膜的润湿性能,用红外光谱、X射线衍射表征了膜表面的基团变化及物相变化,用热重分析仪考察了改性后薄膜的热稳定性,并测试了改性后薄膜的黏附性能。结果表明,改性后薄膜的表面能由28.64 mJ/m2提高到41.48 mJ/m2,剪切强度由150.5 kPa提高到219.5 kPa,表面能的提高主要是由于聚合物链的氯苯发生还原反应引起。     

Morphology and thermodynamic analysis of composite polymer particles prepared by soap‐free emulsion polymerization in the presence of poly(methyl methacrylate) and polystyrene as biseeds

Biseeds emulsion polymerization was investigated with poly(methyl methacrylate) (PMMA) and polystyrene (PSt) as biseeds and styrene (St) as second‐stage monomer, as well as with thermodynamic analysis; namely, the principle of minimum interfacial free‐energy change was utilized to explain the competitiveness of different seeds for second‐stage monomer and the final equilibrium morphology of composite polymer particles. The experimental results indicated the polymeric particles prepared had bimodal size distribution and the PMMA seed particles showed a higher chance of obtaining St than that of the PSt seed particles, which was in agreement with the computational outcome by the principle of minimum interfacial free‐energy change. Owing to the kinetic factors, the equilibrium morphology could not be reached in the experiments. However, the results demonstrated that double or multiple seeds emulsion polymerization could be used as a model experiment to study the morphology of polymer particle and the morphological prediction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2675–2680, 2004     

Characterization of sulfonated poly(styrene–divinylbenzene) and poly(divinylbenzene) and its application as catalysts in esterification reaction

Polymeric supports based on divinylbenzene (DVB) were prepared by aqueous suspension polymerization in presence or absence of styrene (S), using toluene and n‐heptane as diluents of the monomers. Poly(S–DVB) and poly(DVB) were sulfonated with sulfuric acid in presence of 1,2‐dichloroethane. The influence of the morphological structure of the supports and as a consequence of the catalyst on the esterification reaction of acetic acid with n‐butanol was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3616–3627, 2006     

聚氯代对二甲苯表面原位引发接枝聚合提升膜表面能的研究

通过钠-萘络合物的处理,在聚氯代对二甲苯膜表面形成自由基,通过表面自由基原位引发甲基丙烯酸甲酯聚合,在薄膜表面引入极性基团以提高膜表面黏结性能。利用红外光谱、X射线衍射和显微镜对接枝改性后薄膜的化学组成和表面形貌进行了表征,运用聚合物膜表面接触角的变化表征了其改性效果。结果表明,甲基丙烯酸甲酯单体由聚氯代对二甲苯膜表面自由基引发,从Cl位置接入,接枝链以共价键的形式与聚氯代对二甲苯膜连接;接枝改性后聚氯代对二甲苯膜表面出现-C=O的特征吸收峰,-CH2的吸收峰随接枝时间的延长而逐渐增大;接枝后薄膜的表面能由28.6 mJ/m2提高到54.1 mJ/m2,拉伸强度由150.5 kPa提高到222.5 kPa。