硅烷偶联剂在二氧化硅基片表面吸附膜的形貌

使用原子力显微镜(AFM)观测了吸附在二氧化硅基片表面的硅烷偶联剂薄膜的形貌.结果表明,在气相法吸附过程中偶联剂是以分子形态吸附在基片表面,而在液相法吸附过程中偶联剂是以分子聚合体的形态吸附在基片表面,因此通过气相法吸附在基片表面的吸附膜比通过液相法吸附在基片表面的吸附膜光滑.硅烷偶联剂在二氧化硅基片表面有化学吸附和物理吸附两种模式,吸附了硅烷偶联剂薄膜的基片表面呈现出一定的疏水性.     

Characterization of the interfacial bond between old concrete substrate and ultra high performance fiber concrete repair composite

The interfacial bond characteristics between normal concrete substrate as old concrete and ultra high performance fiber concrete as repair material have been investigated. Normal concrete substrates were first subjected to different surface preparation methods prior to bonding the ultra high performance fiber concrete to form repair composites. The interfacial mechanical bond of the composites was assessed using slant shear and tensile splitting strength tests. In addition, rapid chloride permeability test was performed to ascertain the potential chloride resistance of the composites. The microstructure of the transition zone between the normal concrete and ultra high performance fiber concrete was also studied using scanning electron microscope. The results generally indicate that surface preparation of the substrate is very much required to obtain superior mechanical bond of the composites; whereby the composites with the sand-blasted substrate providing the most superior mechanical bond. The excellent bond of the composite is also evident through the rapid chloride permeability test, as well as confirms by the scanning electron microscope image of the interface. Hence, the ultra high performance fiber concrete exhibits significant potential as an excellent material for repair and rehabilitation of concrete structures.     

硅烷偶联剂及氧化石墨烯二次改性对芳纶纤维界面性能的影响EI北大核心CSCD

为改善芳纶纤维(PPTA)与丁腈橡胶(NBR)复合材料之间的界面强度,采用硅烷偶联剂A172和氧化石墨烯(GO)对芳纶纤维表面进行接枝改性处理,并对处理前后的芳纶纤维进行化学结构、表面形貌及H抽出力分析。利用SEM对抽出纤维表面和橡胶基芳纶纤维复合材料截面进行微观结构分析。结果表明:硅烷偶联剂和氧化石墨烯对芳纶纤维进行二次表面改性后,纤维表面含氧基团增加,化学活性提高,处理后表面存在明显的表层附着物,纤维结构未发生明显损伤且表面粗糙度得到明显改善。每个处理阶段后H抽出力均有提高,且氧化石墨烯二次改性后的芳纶纤维H抽出力提高效果最佳,从18.192 MPa提高到48.748 MPa,芳纶纤维与丁腈橡胶的界面结合力得到了显著提升,从而证实了硅烷偶联剂和氧化石墨烯二次改性芳纶纤维的有效性,为橡胶基芳纶纤维复合材料性能的研究提供了参考。     

偶联剂在溶胶中的应用研究

采用激光粒度仪、透射电子显微镜(TEM)、傅里叶红外分析测试仪(FTIR)以及紫外可见分光光度计(UV-Vis)等测试手段,研究了在酸性条件下制备SiO2溶胶过程中硅烷偶联剂(KH-570)对二氧化硅(SiO2)溶胶性能的影响.结果表明:加入硅烷偶联剂改性的SiO2溶胶体系分散均匀无团簇,并且由此制得的SiO2薄膜透光率高于没有经过改性的薄膜.     

硅烷偶联剂改性聚氨酯的研究

从原料和工艺两方面出发,对以γ-氨丙基三乙氧基硅烷(KH550)为基础的硅烷改性聚氨酯(SPU)进行了改善.原料方面,改性后的KH550由伯氨基转化为仲氨基,反应活性降低;工艺方面,将KH550加料顺序提前.试验结果表明:这两种方法均有利于降低SPU树脂的黏度和提高反应平稳性;较好解决了由于黏度上升太快引起的KH550自聚凝团问题.     

长链烷基硅烷偶联剂的合成研究

以甲基二氯硅烷与1-十二碳烯在铂催化剂作用下合成了甲基十二烷基二氯硅烷,并以无溶剂气-液相反应法醇解得到了甲基十二烷基二甲氧基硅烷。考察了催化剂对加成反应及原料配比、温度、填料大小等因素对醇解反应的各种影响。确立了最佳的反应条件。     

硅烷偶联剂对铸造用碱酚醛树脂黏结强度的影响

通过黏结强度的测定和SEM分析,研究了硅烷偶联剂对碱酚醛树脂性能的影响.试验结果表明,硅烷偶联剂可以改善黏结剂与砂粒表面的接触状态,极大地提高碱酚醛树脂砂的黏结强度.     

Modification effects of nanosilica on the interfacial transition zone in concrete: A multiscale approach

The effects of colloidal nanosilica on the interfacial transition zone (ITZ) in concrete at three days are studied. Mechanical properties are investigated at macro-scale, followed by nanoindentation characterization at micro-scale. A top-down and a bottom-up modelling are carried out, respectively, at macro- and micro-scales. Macro-mechanical results show that nanosilica addition is especially beneficial for the improvement of ITZ performance. Estimates from statistical nanoindentation provide evidence, suggesting that the hydration acceleration effect of nanosilica dominates in the modification of ITZ in an early age. It is revealed by modelling at both scale levels that the ratio of the Young's modulus of ITZ to that of bulk paste increases from around 50%–80% if nanosilica is incorporated. This work further confirms that a substantial improvement on ITZ can be obtained by ultra-fine nanosilica modification.     

有机硅烷偶联剂对水性聚氨酯材料性能的影响

以IPDI为硬段,PTMG1000为软段,TMP为交联剂,APTES为封端剂,合成了一系列硅烷偶联剂改性水性聚氨酯乳液,并制备了水性聚氨酯的固化膜.FT-IR分析表明,APTES上的一NH2 与聚铵酯的端--NCO发生反应,成功地将硅烷结构引入聚氨酯分子中.TG分析表明,APTES的改性,提高了聚氨酯热稳定性.随着w(...     

Effect of silane coupling agent on mechanical performance of glass fibre

Mechanical performance of commercially manufactured unsized and γ-aminopropylsilane sized boron-free E-glass fibres has been characterised using single-fibre tensile test. Both apparent fibre modulus and fibre strength were found to strongly depend on fibre gauge length. The average strength of sized fibres was found 40–80 % higher than unsized fibres at different gauge lengths. Weibull analysis suggested that the failure mode of unsized fibres could be described by unimodal Weibull distribution, whereas the strength distribution of sized fibres appeared to be controlled by two exclusive types of flaw population, types A and B. Comparison of the Weibull plots between unsized and sized fibres revealed that the strength of unsized fibres was likely to be dominated by type A flaws existing on the bare glass surface and type B flaws may be related to the defects on the glass surface coated with silane. This was partially supported by the observation of fractured cross-sectional area using SEM. It was, therefore, proposed that the strength difference between unsized and sized glass fibres may be more reasonably interpreted from the surface protection standpoint as opposed to the flaw healing effect. The results obtained from this study showed that silane coupling agent plays a critical role in the strength retention of commercially manufactured E-glass fibres and the silane effect on the fibre strength is also affected by the change in gauge length of the sample.     

Surface modification of nano-TiN by using silane coupling agent

Titanium nitride (TiN) nano-particles were subjected to graft modification by silane coupling agent (KH-570) via a direct blending method. The hydroxyl groups on the surface of TiN nano-particles can interact with silanol groups [-Si-OCH₃] of KH-570 forming an organic coating layer. The covalent bonds (Ti-O-Si) formation was testified by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Through transmission electron micrograph (TEM) observations, it was found that KH-570 could improve the dispersibility of nano-TiN particles in ethyl acetate. Thermo gravimetric analysis (TGA) and contact angle measurements indicated that KH-570 molecules were adsorbed or anchored on the surface of nano-TiN particle and the net efficiency of it was 22.76 %, which facilitated to hinder the aggregation of nano-TiN particles.     

偏高岭土-矿渣基地聚物与花岗岩骨料界面的分布特性及影响因素

以碱激发偏高岭土-矿渣作为胶凝材料、花岗岩为骨料制备地聚物混凝土,通过扫描电镜SEM-EDS及显微硬度分析研究地聚物与骨料的界面粘结区的微观结构、分布,以及液固比和骨料尺寸对地聚物-骨料界面的影响。研究结果表明,在地聚物与骨料的界面区域存在界面过渡区(ITZ),包含了以N-A-S-H凝胶为主的固相和收缩裂缝,化学组分与地聚物凝胶有较大不同。界面过渡区沿骨料周围不同位置表现出明显的分布不均匀特性,骨料下缘处的界面过渡区的微观结构和硬度都显著更差。随着液固比及骨料半径的增大,其分布的不均匀性增加:骨料下界面ITZ中的裂缝宽度增大,N-A-S-H凝胶厚度减小且强度降低;但配比及骨料尺寸对骨料上界面及侧界面的ITZ影响并不显著。骨料下界面ITZ应是偏高岭土-矿渣基地聚物混凝土的薄弱区域。     

硅烷偶联剂对集料表面改性的制备及性能表征

利用硅烷偶联剂对集料进行表面改性,使其与集料发生水解和固化反应。基于表面能理论、红外光谱(FTIR)和扫描电镜(SEM)等微观分析手段对改性前后的集料进行表征,通过直接拉伸、水煮法、浸水马歇尔试验和冻融劈裂试验等宏观手段对改性前后的集料性能进行验证。结果表明硅烷偶联剂表面改性后的集料接触角减小,由原来的亲水性变为亲油性;红外光谱(FTIR)发现硅烷偶联剂与集料之间产生了Si—O—C、Si—O—Si共价键和氢键;扫描电镜(SEM)观测到集料表面形成了一层聚硅氧烷偶联层薄膜,表明集料表面已引入了硅烷偶联剂中的亲油基团;浸水前后表面改性的集料比原集料抗拉强度损失率下降了42.2%;集料与沥青之间的粘附性等级可达到5级,沥青混合料残留稳定度提升11.54%,冻融劈裂强度比提升39.26%。说明了硅烷偶联剂成功对集料进行表面改性,并改善了集料的表面性能。     

Statistical relationship between mix properties and the interfacial transition zone around embedded rebar

The relationship between concrete mix properties and the properties of the interfacial transition zone (ITZ) formed around embedded rebar was investigated. Multiple samples of various mix compositions and bar orientations were prepared so as to represent common concrete technology. Water-to-cement ratios varied from 0.40 to 0.65 and powder (cement + limestone filler) contents ranged from 362 kg/m³ to 564 kg/m³. Over 1300 BSE images of the steel–concrete interface were taken and analyzed automatically. Statistical methods were used to identify correlations between ITZ properties and mix composition or fresh mix properties.A single large void was identified beneath all horizontal bars regardless of concrete composition. The ITZ around vertical bars was more uniform and extended around the entire rebar. No clear relationship was found between ITZ thickness and mix composition or fresh mix properties for either vertical or horizontal bar orientations. The degree of ITZ variability beneath horizontal bars clearly depends, however, on the bleeding properties of the mix. The distance from steel surface to the closest concrete solid, which influences the chemistry over the surface of the steel, is affected by precipitation of hydration products in horizontal bars, but not by mix composition.     

硅烷偶联剂核交联聚丙烯酸酯多元醇乳液的合成及表征

以硅烷偶联剂作为交联剂,制备了具有核交联结构的聚丙烯酸酯多元醇乳液(Si-PHA),并用FTIR、TEM、粒径分布仪对乳液进行结构表征.FTIR、TEM和粒径分布仪均证实,硅烷偶联荆在聚合过程中发生了部分水解、缩合反应,得到具有核交联结构的Si-PHA.Si-PHA乳胶粒为表面具有凹陷结构的近似球体,且粒径呈单分散分布.Si-PHA乳胶粒内的硅氧烷在贮存期间会继续发生水解、缩合反应,乳胶粒粒径进一步变小.     

Wave reflection on a continuous transition zone between two homogeneous materials

Summary The one-dimensional wave propagating from one homogeneous material to another homogeneous material is analyzed. Between these two materials there exists an inhomogeneous transition zone. Each material is elastic. The elastic constants are smooth functions in the transition zone and possess no jump at their boundaries.     

硅烷类偶联剂对蓄光性荧光粉的表面处理

采用硅烷类偶联剂对蓄光性荧光粉YLAG进行了表面处理,并将荧光粉与尼龙66(PA66)进行熔融共混,利用散射式浊度仪、透射电镜、红外光谱、扫描电镜分别研究了表面处理前后荧光粉的沉降性、微观形貌及化学结构的变化,以及荧光粉/聚合物共混体系的形态结构.结果表明,经硅烷偶联剂进行表面处理后,荧光粉与偶联剂有一定键合作用,表面处理后荧光粉的沉降速度明显减小,在PA66中的分散性得以改善.     

硅烷类偶联剂KH-570对T-ZnOw的表面改性研究

选用硅烷类偶联剂KH-570对T-ZnOw进行湿法表面化学改性。探讨了改性条件对改性效果的影响,并采用活化指数、接触角测定、红外光谱测定等手段对改性效果作了表征。结果表明,对T-ZnOw表面改性的最适宜的条件为:pH值为6,室温下水解1h,偶联剂用量为3%,在65℃偶联2h。采用改性方法和条件,可以取得满意的改性效果,改性后的T-ZnOw分散性得到了明显改善。     

硅烷偶联剂对碳微球的表面化学修饰

首先采用混酸体系对碳微球(CMSs)表面进行氧化处理,使CMSs表面引入含氧官能团,进而以γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)与CMSs表面发生缩合反应,得到了表面有机修饰的CMSs.利用傅立叶红外光谱仪、场发射扫描电子显微镜、X射线光电子能谱等检测手段对各阶段的产物进行了形貌和结构表征,并研究了其在乙...     

硅烷偶联剂对单壁碳纳米管的化学修饰

采用混酸体系(浓硫酸/浓硝酸体积比为3/1)对单壁碳纳米管进行了氧化处理,并通过氧化处理后在单壁碳纳米管表面生成的羟基官能团与长链硅烷偶联剂进行反应,制备了表面有机修饰的单壁碳纳米管.经过该方法修饰的碳纳米管在三氯甲烷、四氯化碳和二硫化碳等有机溶剂中有较好的溶解性.并通过红外光谱、热失重和透射电镜对其化学结构进行了表征.