白炭黑的功能化改性及其改性橡胶基复合材料的制备与表征

利用沉淀法白炭黑生产工艺,在相同的条件下,选用不同质量分数的羟基羧酸酯作为改性剂进行湿法改性,研究了白炭黑/天然橡胶(NR)复合橡胶的力学性能、动态性能以及动态生热性能。结果表明:制备的白炭黑均为非晶态白炭黑,采用质量分数为6%的羟基羧酸酯改性的白炭黑,其分散性好,颗粒分布均匀,呈近球状,经羟基羧酸酯改性后的白炭黑有效的去除了部分亲水基团,改善了其在NR中的分散性。随着白炭黑用量的增加,分散性变差,损耗因子和动态温升均有所提高,Payne效应增大。当白炭黑用量达到临界值(白炭黑与NR质量比为40∶100)时,白炭黑/NR复合材料表现出较好的性能,改性白炭黑/NR复合材料比未改性白炭黑/NR复合材料的硬度、拉伸强度、断裂伸长率有所提高,而磨耗体积和动态生热则有所下降。动态力学性能测试结果表明,改性白炭黑与天然橡胶的质量比为40∶100时,改性白炭黑/NR复合材料的60℃滚动阻力损耗因子由0.123降到0.104。SEM结果表明,改性白炭黑在橡胶基体中的分散性优于未改性白炭黑,与NR基体界面结合的更加紧密。     

表面接枝防老剂的白炭黑在天然橡胶中的应用

为了提高白炭黑与橡胶的相容性,同时防止防老剂的挥发,采用γ-缩水甘油醚氧丙基三甲氧基硅烷与对氨基二苯胺(PPDA)的反应物对白炭黑进行表面改性,得到表面接枝防老剂的白炭黑。将改性白炭黑应用于天然橡胶(NR)中考察其增强与防老性能,并与炭黑/NR、未改性白炭黑/NR和Si69改性白炭黑/NR复合材料相比较(均添加防老剂4020)。结果表明,改性白炭黑/NR复合材料的焦烧时间延长,硫化时间缩短,白炭黑在橡胶中的分散性提高,同时具备更出色的力学性能。随着表面接枝防老剂含量的增加,改性白炭黑/NR复合材料的拉伸强度和撕裂强度比未改性白炭黑和Si69改性白炭黑/NR均有大幅提高。当接枝的PPDA含量达到5.27%(与白炭黑的质量比)时,其拉伸强度比未改性白炭黑/NR提高了90%,比Si69改性白炭黑/NR提高了73%,并接近炭黑/NR; 其撕裂强度是未改性白炭黑/NR的5倍,Si69改性白炭黑/NR的2.5倍,炭黑/NR的2倍。另外,表面接枝防老剂的白炭黑/NR复合材料具有优异的抗热氧、抗臭氧和湿热老化性能;其抗臭氧老化性能优于添加通用防老剂4020的对比复合材料。     

丁苯胶/甲基丙烯酸锌/气相法白炭黑纳米复合材料

制备了三相纳米复合材料SBR／ZDMA／气相法白炭黑。采用了两种气相法白炭黑,U—fumed silica是一种未改性的气相法白炭黑,M—fumed silica是一种采用硅烷偶联剂Si69表面改性的气相法白炭黑。主要研究了气相法白炭黑和ZDMA之间的协同补强效应。研究结果显示,单独添加同样份数的改性气相法白炭黑和未改性气相法白炭黑对硫化胶物理机械性能的影响不同,改性气相法白炭黑的效果明显优于未改性气相法白炭黑。单独添加气相法白炭黑,体系的物理机械性能仍然维持在较低值。当同时添加气相法白炭黑和ZDMA时,会观察到明显的协同补强效应。交联密度和丙酮抽出试验表明对气相法白炭黑进行表面改性和在体系中添加ZDMA均会减弱气相法白炭黑表面羟基的影响。扫描电镜显示改性后气相法白炭黑在SBR中的分散性得到提高。在体系中添加ZDMA会提高气相法白炭黑的分散性。     

铜型抗菌白炭黑的改性研究

通过添加表面活性剂和有机溶剂对铜型抗菌白炭黑进行改性研究.并运用ICP、粒度分布仪对改性后铜型抗菌白炭黑中抗菌离子含量、粒度进行了表征;利用菌落计数法对改性后材料的抗菌性能进行了研究;并与未改性的铜型抗菌白炭黑进行比较.结果表明,改性后的铜型抗菌白炭黑中,抗菌离子含量高于未改性前;结构较改性前松散,且分散性好;平均粒径为3μm且均一;杀菌率达99%以上.具有较好的热稳定性和光稳定性.     

改性白炭黑的研究进展

介绍了功能性精细无机材料改性白炭黑的结构特征，详述了目前国内外的几种白炭黑的改性工艺方法及其在红外光谱、核磁共振谱、X射线电子能谱及热重分析中的结构性能表征。提出了有利于我国能源资源有效利用的白炭黑改性技术的发展方向。     

离子液体改性白炭黑/天然橡胶复合材料的制备及性能EI北大核心CSCD

用离子液体1-烯丙基-3-甲基氯化咪唑(AMI)改性白炭黑(SiO_2),制备改性白炭黑/天然橡胶(NR)复合材料。采用红外光谱、X射线光电子能谱、扫描电镜等方法分析了改性前后白炭黑的微观结构,研究了AMI对SiO_2/NR复合材料结构与性能的影响。结果表明,AMI改性白炭黑可明显提高白炭黑的分散性,减小白炭黑在橡胶基体中的实际分布粒径,提高白炭黑与橡胶基体的界面相互作用,增加橡胶复合材料的结合胶含量,提高复合材料的综合力学性能。当AMI用量为2 phr时,白炭黑在橡胶基体中的分散性最好,分布粒径最小,结合胶含量最高,综合力学性能最好。与未改性的SiO_2/NR复合材料相比,AMI-SiO_2/NR复合材料拉伸强度提高了18%,撕裂强度提高了41.4%,300%定伸应力提高了39.2%,100%定伸应力提高了25%。     

原位填充改性增强特种胶粘剂粘接强度研究

采用原位填充白炭黑法增强甲基丙烯酸（酯）改性RTV胶粘剂,选用IR、SEM等分析方法对增强改性RTV胶粘剂的结构、分散性进行表征,结果表明：部分白炭黑与甲基丙烯酸（酯）改性硅橡胶形成共聚物,白炭黑分散非常均匀。将增强改性RTV胶粘剂粘接JOB9003炸药时,剪切强度明显提高,达到3．5MPa,白炭黑含量在1％～2．5％时补强效果较好。     

银型抗菌白炭黑的改性研究

通过添加表面活性剂和有机溶剂对银型抗菌白炭黑进行改性研究。运用ICP、粒度分布仪对改性后银型抗菌白炭黑中抗菌离子含量、粒度分布进行表征;利用菌落计数法对改性后材料的抗菌性能进行研究;并与未改性的银型抗菌白炭黑进行比较。结果表明,改性后的银型抗菌白炭黑中抗菌离子含量高于未改性前;结构较改性前松散,且分散性好;粒径主要分布在3~6μm且均一;具有较好的热稳定性和光稳定性。     

光棒废料中提取的白炭黑的疏水化改性

为找出光纤预制棒废料中提取的白炭黑的改性效果好的硅烷偶联剂,用KH-560、KH-151、KH-171、KH-602和CG-551等10种硅烷偶联剂对该白炭黑进行改性。白炭黑在140℃下活化20 h,将活化的白炭黑3 g分别与10种不同的偶联剂0.3 m L在45 m L二甲苯溶剂中130℃加热搅拌13 h,离心分离后,固体样品加适量的无水乙醇洗涤烘干后即得到改性的白炭黑。改性后样品的沉降性、亲油化度、表面羟基数等实验结果表明,10种硅烷偶联剂都能对白炭黑进行改性,其中KH-560、CG-8030、KH-151、KH-171、KH-172、KH-570对白炭黑的改性效果优于含氨基或巯基的KH-602、KH-792、CG-551、KH-550等。     

离子液体改性白炭黑/天然橡胶复合材料的制备及性能

用离子液体1-烯丙基-3-甲基氯化咪唑(AMI)改性白炭黑(SiO_2),制备改性白炭黑/天然橡胶(NR)复合材料。采用红外光谱、X射线光电子能谱、扫描电镜等方法分析了改性前后白炭黑的微观结构,研究了AMI对SiO_2/NR复合材料结构与性能的影响。结果表明,AMI改性白炭黑可明显提高白炭黑的分散性,减小白炭黑在橡胶基体中的实际分布粒径,提高白炭黑与橡胶基体的界面相互作用,增加橡胶复合材料的结合胶含量,提高复合材料的综合力学性能。当AMI用量为2 phr时,白炭黑在橡胶基体中的分散性最好,分布粒径最小,结合胶含量最高,综合力学性能最好。与未改性的SiO_2/NR复合材料相比,AMI-SiO_2/NR复合材料拉伸强度提高了18%,撕裂强度提高了41.4%,300%定伸应力提高了39.2%,100%定伸应力提高了25%。     

Fabrication of nanoscaled silica layer on the surfaces of submicron SiO2-Ag core-shell spheres

A two-step silica deposition process, including prefunctionalization with poly(vinylpyrrolidone) and the following silica deposition, has been used to fabricate silica layer on the surface of nanoscaled silver shell. The influencing parameters of silica coating process were optimized to prevent the precoated silver nanoparticles from desquamating from silica spheres, finally to obtain mono-dispersed silica spheres with silver and silica multilayer films. The resulted silica layer was dense and uniform, its thickness was controllable in the range of 20–50 nm. Such coated silica layer can provide improved thermal stability of the SiO₂-Ag core-shell structural spheres.     

Fabrication of hollow silica spheres and their application in polyacrylate film forming agent

Polystyrene (PS)/silica core/shell spheres were fabricated using mono-dispersed PS as templates by hydrolysis and condensation of two different silica precursors. The PS cores of PS/silica core/shell spheres were dissolved subsequently in the tetrahydrofuran medium to form mono-dispersed hollow silica spheres. The structures and morphologies of hollow silica spheres were characterized by scanning electron microscopy and transmission electron microscopy. Then, polyacrylate/hollow silica composite film forming agents were prepared via physical blending of polyacrylate and two different hollow silica spheres, and the water vapor permeability of their films were compared. The results showed that the structure of hollow silica spheres were very typical and obvious. The silica shell was continuous and uniform using tetraethylorthosilicate as precursor, which was accumulated by many silica seeds with size of 10–20 nm, and the thickness of silica shell was about 16.7 nm. However, the hollow silica spheres using tetraethylorthosilicate and vinyl triethoxysilane as precursors had mesoporous structure in the shell. The introduction of hollow silica spheres could significantly improve the water vapor permeability of polyacrylate film. At last, a possible mechanism for the formation of hollow silica spheres was proposed and the process of water vapor through polyacrylate/hollow silica composite films was modeled.     

纳米硅胶的仿生合成研究

介绍了硅胶仿生合成中硅前体和有机大分子添加剂的类型及其作用机制,重点讨论了纳米硅胶仿生合成的影响因素.硅前体主要影响硅胶形成的动力学速度,对于一定的硅前体,尤其是有机硅前体,溶液的pH、预水解时间、硅前体的浓度、反应时间、反应温度和搅拌速率等都是控制硅胶产物形成的因素.有机大分子添加剂主要对硅胶的晶核形成和长大起到定向模板的诱导作用,是决定硅胶粒子大小、结构和形态的主要因素,来自生物体或仿生合成的有机聚阳离子或能与硅氧离子形成氢键的聚合物是理想的添加剂类型.反应介质的性质能对有机大分子添加剂的诱导作用产生一定的影响.     

On the Origin and Underappreciated Effects of Ion Doping in Silica

The origin of selectivity in the hollowing of silica nanoparticles is investigated to further understand silica. It is realized that, during the synthesis, the silica precursors are essentially ion‐paired polyelectrolytes, whose nucleation depends on the concentration of the counter ions, and most importantly, the size/length of the poly(silicic acid). Thus, the “silica” that nucleates out at the different stages of synthesis has different degrees of ion doping, which explains its solubility in water, its microporosity, and the selective etching phenomena. The etching of silica in water is shown to be a matter of silica solubility, which correlates to the relative amounts of solvent and to the solvent quality (the water/isopropanol ratio). Hollowing does not occur when the silica nanoparticles are incubated in solutions presaturated with “silica,” ruling out surface reposition and Ostwald ripening as the hollowing mechanism. The embedded ions in silica are confirmed by elemental analysis (CHNS) and inductively coupled plasma‐mass spectrometry. The high ionic doping ratios (N/Si = 2.3% for NH₃‐catalyzed silica; Na/Si = 11.2% for NaOH‐catalyzed silica) explain the unusual solubility of silica in neutral water. The new view of silica with the ionic impurities on the central stage allows for insights in silica properties and versatility in synthetic design.     

Synthesis of sustainable silica xerogels/aerogels using inexpensive steel slag and bean pod ash: A comparison study

Low cost silica xerogels/aerogels were synthesized from steel slag and bean pod ash by sol–gel method. Comparison study showed differences between structural, morphological, textural, thermal and physical properties of the silica xerogels and aerogels. Formation of amorphous structure and silica network was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analyses, respectively. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses revealed that silica xerogels had smaller interlinked network in contrast to silica aerogels. Typical type IV isotherm was observed for all samples in N₂ adsorption-desorption isotherms. The highest surface area was determined as 371 m² g⁻¹ for silica aerogel synthesized from steel slag. Particle size of silica aerogels was lower than that of the silica xerogels. The more porous structure made silica aerogels desirable materials with lower bulk density and thermal conductivity when compared to silica xerogels. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) exhibited high thermal stability of the silica xerogels/aerogels. Although silica xerogels had highly hydrophilic structure, contact angle of silica aerogels synthesized from steel slag and bean pod ash was 60° and 74°, respectively. The comparison study will give a new point of view about differences between silica xerogels and aerogels synthesized from by-products or inorganic/organic waste instead of silicon alkoxides.     

改性硅气凝胶/聚甲基丙烯酸甲酯乳液的制备与性能研究

采用HMDS(六甲基二硅氮烷)改性硅气凝胶,通过乳液聚合法,将改性硅气凝胶与甲基丙烯酸甲酯(MMA)进行聚合,制得改性硅气凝胶/聚甲基丙烯酸甲酯复合乳液,并且讨论了硅气凝胶的表面状态,以及改性气凝胶质量分数对复合乳液性能的影响。结果表明:HMDS可成功修饰于硅气凝胶表面,将改性硅气凝胶与PMMA乳液体系复合,乳液综合性能呈现较为显著的变化。HMDS修饰的硅气凝胶有助于降低乳液的导热系数,加入3%HMDS修饰的硅气凝胶可以使成膜后的乳液具有较低的导热系数。     

Ultrafine polyacrylonitrile/silica composite fibers via electrospinning

Polyacrylonitrile (PAN)/silica composite nanofibers, in the diameter of 200-300 nm, were prepared by a one-step electrospinning method. The PAN/silica nanofibers were characterized by SEM, TEM, ATR-FTIR and DSC. SEM and TEM images show that beads are formed and silica nanoparticles start to aggregate when the silica content is higher than 2 wt.% in nanofibers. ATR-FTIR spectra and DSC results indicate that there may exist interactions between silica nanoparticles and PAN. The addition of silica nanoparticles also changes the thermal properties of PAN/silica nanofibers.