Analysis of Spectral Signatures of Silicone-Based Sealant Materials Used in Residential and Commercial Buildings

In the construction industry, silicone is primarily used as sealant material to fill gaps and cracks providing water and air-tightness to vertical construction projects reducing energy usage bills and enhancing the integrity of construction materials. This paper reports the results of spectral analysis of commonly used building sealant materials used in residential and commercial buildings. A dozen commercially available silicone-based sealant materials composed of different ingredients representing three manufacturer brands are characterized using Raman and UV-VIS-NIR spectroscopic techniques. The characteristic vibrational fingerprints of the selected sealant materials are summarized, and the Raman and reflectance spectra of the samples are also presented. It is observed that most of the samples appear to have similar vibrational band assignments and reflectance spectra. However, analysis of the Raman spectral positions and the reflectance spectra reveals that there are distinct differences among the sealant materials.

TRIMETHYLSILYLATED SILICA AS RHEOLOGY MODIFIER FOR SILICONE RESINS

Trimethylsilylated silica was synthesized. through hydrolytic condensation of tetraethoxysilane followed by trimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. It turned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylated silica of medium particle size shows the strongest tendency of forming physical network in the resin.

Effects of Ultraviolet Radiation,High Temperature and Alkaline Chemicals on Ageing of Silicone Sealants Used in Ballastless Track Expansion Joints

Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation（UV）, high temperature combined with the alkaline environment. To evaluate the durability and analyse the ageing mechanism, six one-component silicone sealants from different companies were selected and subjected to accelerated ageing tests including UV, thermal and alkali ageing treatments. The ageing effects on the performance of the sealants were evaluated via the appearance and the mechanical property changes. The changes in molecular structure were studied by means of Fourier transform infrared spectroscopy（FTIR）, differential scanning calorimetry（DSC） and thermogravimetry（TG）. This study revealed that different materials displayed different sensibilities to the ageing methods, in which 15 %-20 % decreases of mechanical properties could be observed under UV radiation test, owning the most significant effects. Structure analysis showed that the physical changes of aggregative states were the principal factors to the performance, along with the chemical slight changes. The glossiness dropped significantly in ageing test, which could be used as one of the effective evaluation parameters for ageing conditions in the field.

Development and Evaluation of Nano-Silica Dispersed Polyurethane Based Coatings for Improved Anti-Graffiti and Scratch Resistance

Polyurethane based anti-graffiti coatings have been developed by incorporating varying amounts of OH-functional Silicone modified polyacrylate. Optimization of Silicone polyacrylate concentration in neat PU was done by testing its performance for graffiti resistance. Tests which include static contact angle measurements with water and spray paint, visual inspection of stain removal and color change measurements were performed. It was observed that 5 wt % of Silicone polyacrylate in the neat PU showed 95% stain removability. These coatings showed excellent graffiti resistance but poor mechanical properties. Hence modification of these coatings was done by nano-particle incorporation. Nano-silica particle concentration was optimized for surface mechanical properties such as surface hardness, elastic modulus and scratch resistance. FEG-TEM revealed that nano-silica particles were uniformly distributed over the surface. 5 wt % nano-silica particle additions in PU-5 wt % silicone polyacrylate base showed superior mechanical properties than other concentrations. Color change measurements showed that nano-silica particle addition had no effect on its graffiti resistance. Hence PU-5 wt % silicone polyacrylate, 5 wt % nano-silica showed excellent graffiti resistance and mechanical properties.

Analysis of RTV Silicone Sealant Sector

The room-temperature vulcanized (RTV)silicone sealant sector, which belongs tothe technology-intensive industry, startedearlier in developed countries in Europeand America, and RTV silicone sealant wascommercialized in early 1950s. In contrast,the commercialization of RTV silicone sealantstarted rather late in China, and RTVsilicone sealant has been used here mainlyin certain sectors such as aviation/spaceflight. During 1980s, domestic specializedresearch institutions led byChenguang Research Institute of ChemicalIndustry began to research its civilapplications. Then in the 1990s,

High-temperature Reaction of Silica Fume-Si_3N_4 System

The specimens were prepared by molding the mixture of silica fume （ w（ SiO2 ） =94. 5% ; average particle size ： 0. 08 μm ） and silicon nitride （ ≤ 0. 074 mm ） with a mass ratio of 1 ： 1, carbon embedded firing at 1 300 ℃, 1 450℃, 1 500℃, 1 550 ℃ and 1 600 ℃ for 3 h in air, and then water-cooling, respectively. The microstructure and phase composition of the specimens were analyzed. The results show that： （1） silica fume reacts obviously with Si3N4 forming Si2N2O above 1 550 ℃. The edges and corners of Si3N4 grains become smooth and the Si3 N4 grains distribute in the continuous cementation phase of Si2N2O forming the dense structure of Si2N2o packed Si3N4 ; （2） below 1 500 ℃ , the edges and corners of Si3N4 grains are clear, Si2N2O doesn＇t form, and only SiO2 crystallizes from silica fume which happens obviously at 1 300 ℃.

Four-wave mixing in silicon-nanocrystal embedded high-index doped silica micro-ring resonator

A nonlinear integrated optical platform that allows the fabrication of waveguide circuits with different material composition,and at small dimensions,offers advantages in terms of field enhancement and increased interaction length,thereby facilitating the observation of nonlinear optics effects at a much lower power level.To enhance the nonlinearity of the conventional waveguide structure,in this work,we propose and demonstrate a microstructured waveguide where silicon rich layer is embedded in the core of the conventional waveguide in order to increase its nonlinearity.By embedding a 20 nm thin film of silicon nanocrystal(Si-nc),we achieve a twofold increase of the nonlinear parameter,γ.The linear relationship between the fourwave mixing conversion efficiency and pump power reveals the negligible nonlinear absorption and small dispersion in the micro-ring resonators.This simple approach of embedding an ultra-thin Si-nc layer into conventional high-index doped silica dramatically increases its nonlinear performance,and could potentially find applications in all-optical processing functions.

Production of High-Purity Silica Sand from Ivorian Sedimentary Basin by Attrition without Acid Leaching Process for Windows Glass Making

To produce high-purity silica sand usable for glass making, the present study was carried out. The objective of this work was to increase the silicon dioxide (SiO2) content to at least 99% using a simple process without chemical input. The raw sand samples were taken from the Ivorian sedimentary basin, from Maféré and Assinie areas, Côte d’Ivoire. Wet sieving and attrition technique were used for the purification process. The results from the energy dispersive spectrometer (EDS) analyses of the raw and treated samples show a significant increase of silica content and a significant reduction of impurities. The silica content (SiO2) of the sand of Maféré increases from 98.73% ± 0.15% to 99.92% ± 0.05%. And the sand of Assinie increased from 98.82% ± 0.67% in the raw samples to 99.44% ± 0.27% after treatment. The rate of iron oxide and alumina is reduced in these sands. Moreover, the sand of Maféré contains 53.2% of grains of size lower than 500 microns and that of Assinie contains 29.30%. Regarding the chemical composition of these purified sands, they meet the standard BS2975s, the American Ceramic Society and the National Bureau of Standards for window glass making.

Effects of precoating and calcination on microstructure of 3D silica fiber reinforced silicon nitride based composites

Three-dimensional silica fiber reinforced silicon nitride based composites were fabricated by preceramic polymer infiltration and pyrolysis method using perhydropolysilazane as a precursor. The effects of precoating and high temperature calcination on the microstructures of the composites were investigated by scanning electron microscopy. For the composite without a precoating, the fracture surface is plain, and the fiber/matrix interfaces become very unclear after calcination at 1 600 ℃ due to intense interfacial reactions. The composite with a precoating shows tough fracture surface with distinct fiber pull-outs, and the fiber/matrix interfaces are still clear after calcination at 1 600 ℃. It is the appropriate precoating process that contributes to the good interfacial microstructures for the composite.

Modification of Unvulcanized Phenyl Silicone Rubber

In this paper,phenyl silicone rubber is reinforced by precipitated silica which preconditioned with Hexamethyldisilazane.Their damping performance and thermal stability in the air are characterized by rheological test and TG respectively.Results show that the complex viscosity,storage modulus,loss modulus and damping factor of the filling type silicone rubber are improved.

基于有机硅改性聚氨酯/二氧化硅的超疏水棉织物制备及其性能分析

为提高水性聚氨酯整理棉织物的疏水性,采用侧链型聚二甲基硅氧烷与硅烷偶联剂KH550制备交联型水性有机硅改性聚氨酯(WSPU)乳液,然后将疏水二氧化硅(SiO_(2))粒子的分散液喷涂在经WSPU浸轧整理的棉织物表面,制备得到基于WSPU/SiO_(2)的超疏水棉织物。考察KH550的质量分数对WSPU乳液烘干后所得乳胶膜性能的影响,探讨了WSPU与SiO_(2)复合整理棉织物的结构与性能之间的关系。结果表明:当KH550的质量分数为3.0%时,WSPU乳胶膜具有良好的机械性能与疏水性。当SiO_(2)分散液的质量分数为1.0%时,WSPU与SiO_(2)复合整理后的棉织物表面富集硅元素且具有微纳复合结构,织物水接触角达151.8°,滚动角为4.8°,呈现较好的自清洁性能与抗黏附性能;由于复合涂层与纤维间存在物理作用及化学键合,WSPU与SiO_(2)复合整理棉织物具有优异的耐水洗牢度,经20次水洗后水接触角仅下降3.0°。该研究为制备性能稳定的超疏水织物提供了参考。

建筑幕墙密封用多孔硅酮密封胶的制备及保温性能研究

以硅橡胶为基料,多孔硅藻土为填料,制备建筑幕墙密封用多孔硅酮密封胶,并研究其保温性能。结果表明:在一定程度上增大多孔硅藻土用量和延长养护时间会增大多孔硅酮密封胶的表观密度,当多孔硅藻土用量为15份、养护时间为14 d时多孔硅酮密封胶的表观密度较大,孔隙结构调控到了相对较佳状态,保温性能较好;过度延长养护时间、采用水光试验箱养护方式和增大含水率会增大多孔硅酮密封胶的热导率,降低保温性能,当普通养护1~10 d时多孔硅酮密封胶的热导率较小,具有较为理想的保温效果。

纳米银/有机硅密封胶的制备及性能研究

本文采用水热合成法成功合成了纳米银颗粒,然后以聚二甲基硅氧烷为硅油基质,采用物理共混法制备了纳米银/有机硅密封胶。研究了纳米银/有机硅密封胶的微观形貌结构、耐热性能、力学性能以及抗菌性能。结果表明,在纳米银颗粒的质量分数为10%时,所制备的密封胶显示了出色的拉伸强度(4.22 MPa)和高达157.1%的断裂伸长率。同时,该密封胶还表现出卓越的抗菌性能,并且在室温下放置40 d后仍具有良好的抗菌效果,表现出优异的耐久性能。该工作为绿色、健康和清洁的密封应用提供了一种新的思路。

Fabrication of silica-on-silicon planar lightwave circuits by PECVD and ECR

Plasma enhanced chemical vapor deposition (PECVD) and electron cyclotron resonance (ECR) etching were used in the development of silica layers for planar waveguide applications. The addition of GeH4 to silica was used to control the refractive index of core layers with core-to-clad index differences in the range of 0.2%-1.3%. Refractive index uniformity variance of ±0.0003 was achieved after annealing for 4-inch Si (100) wafers. The core layers with thickness up to 6 μm were etched by ECR with optimized recipe and mask material. Low-loss silica-on-silicon waveguides whose propagation loss is approximately 0.07 dB/cm at 1550 nm are fabricated.

High-Q silica microdisk optical resonators with large wedge angles on a silicon chip

We experimentally demonstrate high optical quality factor silica microdisk resonators on a silicon chip with large wedge angles by reactive ion etching. For 2-μm-thick microresonators, we have achieved wedge angles of 59°, 63°,70°, and 79° with optical quality factors of 2.4 × 10~7, 8.1 × 10~6, 5.9 × 10~6, and 7.4 × 10~6, respectively, from ～80 μm diameter microresonators in the 1550 nm wavelength band. Also, for 1-μm-thick microresonators, we have obtained an optical quality factor of 7.3 × 10~6 with a wedge angle of 74°.

Propagation characteristics of the silica and silicon subwavelength-diameter hollow wire waveguides

The basic propagation properties of the silica and silicon subwavelength-diameter hollow wire waveguides have been investigated by comparison. It shows that the silica and silicon subwavelength-diameter hollow wire waveguides have some interesting properties, such as enhanced evanescent field in the cladding, enhanced intensity in the hollow core, and large waveguide dispersion. For the different confinement ability, the enhanced field in the hollow core and cladding of the silica subwavelength-diameter hollow wire is much stronger than that of the silicon one for the same size.

有机硅密封胶中烷烃增塑剂快速检测方法中“薄膜法”浅析

介绍了氟硅行业团体标准T/FSI 088—2022有机硅密封胶中烷烃增塑剂快速检测方法的编制背景,重点阐述了该标准中“薄膜法”快速检测有机硅密封胶中烷烃增塑剂的试验步骤和影响因素。

Design and fabrication of a silica optical micro-kayak cavity on a silicon chip

A new type of silica optical micro-kayak cavity fabricated on a silicon chip is designed and demonstrated. This micro-kayak cavity with two straight sides and two semi-circle sides can be used to achieve a compact and flexible arrangement in the design of integrated photonic circuits. The micro-kayak cavity can also be embedded with a Bragg reflection grating in the straight sides for frequency selection using a micro-kayak cavity laser doped with a rare-earth ion. We describe the fabrication methods for the micro-kayak cavity, obtain its spectra, and discuss its potential applications.

脱酮肟型室温硫化硅橡胶固化深度的影响研究

针对脱酮肟型室温硫化硅橡胶的深层硫化影响因素进行研究,进一步探讨了补强填料添加量、硅油添加量和交联剂用量等因素对脱酮肟型室温硫化硅橡胶的影响;并将在不同条件下的固化深度进行了对比,研究补强填料、二甲基硅油和交联剂对室温硫化硅橡胶固化深度的影响。结果表明,随着补强填料的增加,密封胶固化深度下降,且当其加量过多时,影响更加明显;二甲基硅油的添加量过低时,对密封胶的固化深度无明显影响,随着其添加量逐渐增加后,密封胶的固化深度下降;过量交联剂会导致密封胶的固化深度下降明显。

107胶分子量分布对单组分脱醇型有机硅密封胶性能的影响

本文选取了市面上四种相近黏度、不同分子量分布的α,ω-二羟基聚二甲基硅氧烷为基础聚合物,制备了单组分脱醇型有机硅密封胶。结果表明,随着聚硅氧烷分子量分布的变宽,有机硅密封胶的表干时间差别不大,但邵氏硬度随之增大,而拉伸强度、剪切强度以及最大强度伸长率都呈现出下降的趋势。当分子量分布指数为1.97时,有机硅密封胶在-30℃下展现出了更加优异的性能表现,其拉伸强度和最大强度伸长率均有所升高。