橄榄石酸溶制备超细二氧化硅改性研究

橄榄石酸溶制备超细二氧化硅工艺简单、生产成本低。但是制备的超细二氧化硅表面羟基键合严重、分散性能差、易团聚。利用硅烷偶联剂对橄榄石酸溶制备的超细二氧化硅进行改性研究。采用单因素实验考察了硅烷偶联剂品种、改性时间、改性温度及改性剂用量等因素对超细二氧化硅改性效果的影响。实验结果表明,在硅烷偶联剂KH-550加入量为6 mL/g、改性时间为5 h、改性温度为75 ℃条件下,制备的超细二氧化硅表面的羟基数量减少至2.08×10 ²⁰ 个/g、接枝率为8.35%、接触角达到101.51°,极大地提高了超细二氧化硅的表面疏水性。     

细粒子木质素的制备及其对NBR补强作用

采用自制射流装置制备的细粒子木质素作为橡胶补强剂,研究其对NBR的补强作用.结果表明,黑液酸化的pH值、脱水温度以及黑液与酸混合析出木质素时的湍流程度是影响颗粒细度的主要因素;木质素的粒径越小,对硫化胶的补强效果就越显著,当比表面积从3.0m2@g-1提高到43.5m2@g-1,粒径在100～300nm之间时,36份木质素可使NBR硫化胶的拉伸强度、撕裂强度和扯断伸长率分别达到20MPa,42.0kN@m-1和730%,显著优于半补强炭黑.     

溶胶-凝胶法聚丙烯酸丁酯/二氧化硅杂化材料弹性体的制备与表征

用丙烯酸丁酯与少量功能单体共聚,合成了分子链侧基带羟基的聚丙烯酸丁酯(PBA)乳液,然后与硅溶胶混合,用溶胶-凝胶法制备了PBA/SiO2杂化材料弹性体;研究了SiO2含量对杂化材料弹性体力学性能及透光率的影响,并用扫描电子显微镜、傅里叶变换红外光谱、差示扫描量热分析和动态力学性能分析对杂化材料弹性体的结构进行了表征。结果表明,PBA/SiO2杂化材料热压后成为一种力学性能优良的具有一定透光率的弹性体。随着SiO2含量的增加,杂化材料弹性体的力学性能提高,透光率和SiO2粒子的粒径增加,PBA基体的玻璃化转变温度和损耗因子下降;PBA共聚物分子链侧基所带羟基与SiO2粒子表面的硅醇基发生了缩合脱水反应,形成了Si—O—C共价键,使PBA基体与SiO2粒子构成的界面结合紧密,从而赋予杂化材料弹性体以优良的性能。     

Interface effects in elastomers reinforced by modified precipitated silica

The contributions of the so‐called “interface effects” on the overall viscoelastic behavior of SBR reinforced by precipitated silica modified by model sizing agents are evaluated by using micromechanical models in a reverse mode. According to the nature of the coupling agent, two kinds of “interface effects” can be distinguished: (i) an overall change in the viscoelastic behavior of the polymer matrix, when the sizing agent is a chemical promotor acting as additional ties of the SBR network, and (ii) the formation of an actual mesophase, when direct interactions between SBR chains and silica could occur, as for example, when the coating agent of silica is an organosilane based on short aliphatic chains. With increasing the length of the aliphatic chains of the coating agent (LOS agent), some a plasticisizing effect of the polymer is detected by DSC. It can affect either the entire polymer matrix or a confined region at the close vicinity of silica aggregates. According to this assumption, the bimodal viscoelastic behavior of the LOS‐mesophase revealed by the modeling indicates that in addition to a local plasticisizing effect induced by this agent, some direct interactions could occur between silica surface and SBR constraining the mobility of rubber molecules.     

Simultaneously reinforcing and toughening poly(lactic acid) by incorporating reactive melt-functionalized silica nanoparticles

Simultaneously reinforcing and toughening poly(lactic acid) (PLA) was carried out by adding a small amount of functionalized SiO₂ (f-SiO₂) with grafting degraded PLA chains in this work. Typically, the high shear force and high temperature condition of melt blending were employed to accelerate the degradation of PLA and graft the degraded PLA chains onto SiO₂.The structure characterizations revealed that large quantity of degraded PLA chains were grafted onto the surface of SiO₂ by transesterification, condensation, and esterification reactions during melt blending. Due to the improvement in dispersion and interfacial interaction in PLA matrix, the f-SiO₂ exhibited an effective reinforcing and toughening effect for PLA, where the tensile strength, elongation at break, and impact toughness of PLA/f-SiO₂ nanocomposite increased by 14.9, 47.8, and 30.3% compared to neat PLA. Besides, the degree of crystallinity of PLA was significantly improved by the added f-SiO₂, which also contributed to improving mechanical properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48834.     

用氟硅酸制备高纯氟化钾联产白炭黑工艺研究

以工业副产氟硅酸为原料制备氟化钾,会造成磷酸根和硫酸根在氟化钾产品中的累积从而影响产品质量,而且在使用氢氧化钾碱解的过程中碱的用量不好控制,稍过量就会使二氧化硅溶解从而影响氟化钾的产品质量。重点研究了使用工业副产氟硅酸制备高纯氟化钾联产白炭黑的工艺,解决了杂质累积问题,并从实验原理、实验方法、关键点控制、产品质量及成本等方面进行了深度剖析。该工艺具有生产成本低、产品质量好、工艺合理、环境污染小的特点,符合国家倡导的节能减排和资源综合利用的产业政策。     

Preparation of acylated microcrystalline cellulose using olive oil and its reinforcing effect on poly(lactic acid) films for packaging application

A novel poly(lactic acid) (PLA) based composite, reinforced by microcrystalline cellulose (MCC) was prepared. MCC was modified by esterification reaction using olive oil for improving the compatibility with PLA matrix. The acylated microcrystalline cellulose (AMCC) exhibited reduced polarity in comparison to unmodified MCC. AMCC/ PLA composite films were prepared using solvent casting technique. The effects of the MCC surface modification on morphological, mechanical, physical, thermal, biodegradability and barrier properties of the PLA based MCC composites were studied. FTIR analysis confirmed acylation reaction of MCC. Scanning electron microscopy analysis exhibited a uniform distribution of AMCC in PLA matrix. Barrier properties of AMCC based composites were improved as compared to MCC based composites. The tensile strength and tensile modulus of composite films (at 2 wt.% AMCC) were improved about 13% and 35% as much as those of the pure PLA films, respectively. These biodegradable composite films can be a sustainable utilization of olive oil and microcrystalline cellulose in the food packaging application.     

海泡石改性及其对海泡石—水系统性能的影响

以唐山丰润区海泡石为原料,分别用腐植酸钠、陶瓷减水剂AST、碳酸钠、盐酸对海泡石进行了改性,采用胶质价对改性后的海泡石—水系统悬浮性能进行了测试,实验结果表明:经改性剂处理的海泡石胶质价达到410mL/15g,具有较好的悬浮和流动性能。     

粉煤灰碱溶脱硅液碳化法制备白炭黑的实验与硅酸聚合机理研究

以陕西某热电厂粉煤灰碱溶脱硅液为原料,采用碳化法工艺制备白炭黑.通过正交实验和单因素实验,得到了碳化的优化条件为:实验反应温度85℃,CO2通气速度500 ml·min-1,偏硅酸钠滤液的浓度17.8°Bé,搅拌速度100 r· min-1,反应时间2.5h.采用普通干燥方法,制备了白炭黑制品BTH-01,达到GB10...     

Preparation of ion-containing elastomers by emulsion copolymerization of dienes with olefinic sulfonic acid salts

Procedures were developed for the emulsion copolymerization of either butadiene or isoprene with several different water-soluble monomers containing sulfonic acid salt groups, primarily with sodium styrenesulfonate, for the preparation of ionomer elastomers. By the use of a nonionic surfactant and a two-component redox initiator, which was based on a water-soluble reducing agent and a hydrophobic peroxide, copolymers with sufficient amounts of the ionic monomer could be prepared. Unusual effects of conversion on rate, copolymer composition, and molecular weight were observed and attributed to special effects caused by the ionic monomers. The copolymers were soluble in mixed hydrocarbon–alcohol solvent systems.     

The influence of aluminium on the dissolution of amorphous silica and its relation to alkali silica reaction

It is known that the addition of supplementary cementitious materials (SCMs) in concretes reduces or even stops expansion due to alkali silica reaction (ASR). It has been widely shown that the main mechanism controlling ASR in blends is the alkali fixation capacity of silica rich C–S–H, which lowers the pH of the pore solution. The role of alumina additions is less clear. It was shown in a previous paper [1] that the alumina present in certain SCMs does not further reduce the alkalinity of the paste pore solution. It is proposed here that aluminium acts directly on the reactive phases of the aggregates. Aluminium species, present in the pore solution, are absorbed on the silica surface and limit the dissolution of amorphous silica of the aggregates, restricting ASR. The effect of aluminium was demonstrated through a study of mortar expansion and SEM image analysis of reactive aggregates in simulated pore solutions.     

二氧化硅载过氧磷钨酸季铵盐催化剂的制备及脱硫性能研究

以正硅酸乙酯为硅源,利用溶胶-凝胶法制备了二氧化硅载过氧磷钨酸季铵盐催化剂,对催化剂进行了XRD分析。以双氧水为氧化剂,苯并噻吩(BT)和二苯并噻吩(DBT)为模型化合物,初步评价了催化剂的氧化脱硫反应性能,并考察了反应时间、催化剂用量以及反应温度等反应条件对BT和DBT的氧化脱除效果的影响。结果表明:常压下,反应温度70℃,反应时间60 min,催化剂用量(w)4%,过氧化氢和模拟油体积比1∶10的条件下,对苯并噻吩和二苯并噻吩的脱除效果最好,脱除率分别达到93.75%和97.13%。催化剂可回收多次使用,仍保持较高活性。     

The role of silica in radiation induced grafting and crosslinking of silica/elastomers blends

When silica/polybutadiene and silica/styrene-butadiene are submitted to γ irradiation at 77 K a scavenging of the silica radiolytic species by absorbed vinyl units takes place at the surface with concomitant grafting and crosslinking of the polymers. Key intermediate in such reactions are SiO₂-bonded radicals of structure SiO₂–C^?(CH₃)CH(R)(R′). The role of silica is rationalized in terms of the following steps: a) absorption of the radiation energy in the bulk of the silica particles followed by exciton migration at the surface; b) reactions of excited groups (silanols) with absorbed vinyl units giving SiO₂-bonded radicals; c) crosslinking of the polymers initiated by grafted radicals.     

纳米SiO2的制备方法及其在化妆品中的应用

介绍了纳米SiO2的性质及其应用领域。着重介绍了纳米SiO2的超重力、化学沉淀、溶胶一凝胶、共沸蒸馏、微乳液、激光诱导化学气相沉积等制备方法以及其在化妆品中的应用，并对纳米SiO2的制备方法进行适当的评述。研究开发投资少、生产控制简单的纳米SiO2制备新方法，将会有效的提高纳米SiO2的性价比和扩大纳米SiO2的应用范围。     

Novel anhydrous unfolded structure by heating of acid pre-treated sepiolite

Acid activation of sepiolite removed the brucitic magnesium octahedral layers, while the tetrahedral sheets formed fibrous and amorphous silica. The coexistence of both structures, sepiolite and free silica after the acid treatment, causes changes in the structural behavior of the sepiolite at elevated temperatures. Whereas, the structure of pristine sepiolite is folded by the elimination of the coordinated water molecules, whereas acid pre-treated sepiolite, remains unfolded after the treatment at 550 °C. Therefore, a novel anhydrous unfolded sepiolite structure with empty and open channels was obtained and characterized by X-ray diffraction and ²⁹Si solid state NMR for the first time.     

硅酸凝胶的制备及其对微泡沫的稳定作用

采用十六烷基三甲基溴化铵(CTAB)溶液制备微泡沫,在搅拌过程中加入硅酸钠(Na2SiO3)并用盐酸调节pH以形成硅酸凝胶泡沫,从而改善微泡沫的稳定性。研究了pH和盐酸浓度对硅酸凝胶形成过程的影响;通过光学显微照片观察以及排液行为和流变性测试,对硅酸凝胶泡沫进行了表征。实验结果表明,碱性硅酸凝胶形成的pH范围为10.7～11.2;凝胶化的微气泡呈球形,且气泡界面包覆有凝胶层,可稳定保存48 h以上;硅酸凝胶泡沫表现出非牛顿型流体特征,并具有触变现象。     

Fibre reinforcement of elastomers: nanocomposites based on sepiolite and poly(hydroxyethyl acrylate)

The reinforcement of poly(hydroxyethyl acrylate) provided by sepiolite particles has been analysed. Stress–strain measurements at equilibrium, as well as swelling experiments, were carried out on the unfilled and filled polymers. The state of dispersion of the filler was characterized by transmission electron microscopy. Moreover, an evaluation of chain orientation by infrared dichroism reveals a high orientation level in the filled system. The strong interaction between the two phases, combined with a good dispersion and a high shape factor of these clay particles, explain the improvement of the mechanical properties of the composites with respect to the pure polymer. Copyright © 2004 Society of Chemical Industry     

木质素基二氧化硅复合纳米颗粒的制备及在高密度聚乙烯中的应用

针对目前木质素基SiO₂复合纳米颗粒聚集严重及木质素负载量低,难以应用的现状,以碱木质素为主要原料,先通过磷酸化改性制备磷酸化碱木质素,再利用酸析共沉法将1.2份磷酸化碱木质素与1份纳米SiO₂(均为质量份)复合制备了木质素-SiO₂复合纳米颗粒,并探究复合颗粒对高密度聚乙烯(HDPE)力学性能的影响。FT-IR、XPS、TEM、TG和静态接触角测试结果表明,木质素主要以氢键作用与SiO₂结合;与原料二氧化硅相比,复合颗粒的粒径从25 nm增加到40 nm,聚集程度明显减弱;复合纳米颗粒中木质素占47%(质量分数);表面的疏水性增强,有利于复合颗粒在高密度聚乙烯中均匀分散,显著提高了HDPE的拉伸强度。与碱木质素/HDPE复合材料相比,木质素-SiO₂复合纳米颗粒/HDPE复合材料的拉伸强度和断裂拉伸率分别提高了48.68%和73.57%。     

由蛇纹石酸浸渣制取白炭黑工艺研究

研究了以蛇纹石酸浸渣为原料制取白炭黑的工艺过程,分析了白炭黑产品的形貌和质量。试验结果表明,白炭黑制取过程中SiO2总回收率为88.37%,白炭黑产品为无定形结构,形貌近似球状粒子,平均粒径为1.28μm,化学成分符合HG/T 3061-1999的要求。     

Stepwise dissolution of silica surface in alkaline solution revealed by molecular modeling

The atomic scale solid–liquid interfacial process dominates the macro-dissolution of silica, yet its direct experimental observation is challenging. Here we employed the reactive molecular dynamics to model this process in alkaline condition. An elevated temperature strategy under canonical ensemble (NVT) was applied to accelerate the process for sufficient sampling at temporal domain. A stepwise transformation from fully linked SiO₄ network (Q³ and Q⁴) to reduced linkage and eventually aqueous species (Q⁰) was revealed. The simulated dissolution rate agrees well with the value predicted by empirical model. By tracing hydrogen atoms, we found that the dehydroxylated silica surfaces in alkaline electrolyte solutions underwent a transition from Si–O–Si bond cleavage-dominated (mainly reacted with OH⁻) to hydroxylation-dominated surface reactions. The free-energy reconstruction of well-tempered metadynamics reveals that 1500 K accelerates dissolution without altering the reaction pathways. These findings offer novel insights into the evolution of atomic-scale surface configurations during the dissolution kinetics of silica.