有机硅建筑密封剂老化机理研究

本文探讨了有机硅建筑密封剂潮气固化和降解的机理，并根据理想弹性体概念和理想弹性方程及Ｍａｘｗｅｌｌ模型建立了有机硅建筑密封剂在潮气中曝露时交联和降解的动力学模型。通过实验数据求得了动力学方程。结果表明，有机硅建筑密封剂在潮气中的性能变化呈现两个不可逆的简单的一级反应，即交联反应和降解反应，这两个反应的速度常数分别为ｋ１＝０．０２２４（１／天）和ｋ２＝０．０２７（１／天）。本方程的建立，为有机硅建筑     

Silicone Rubber Composites Modified by Chopped Basalt Fibers Treated with Coupling Agent

To improve the mechanical properties of the silicone rubber, the chopped basalt fiber / silicone rubber composites were prepared in this work, in which the silicone rubber was used as the matrix, the basalt fibers treated with coupling agent were used as the reinforcement. The types and content of coupling agent were determined by testing mechanical properties and thermal properties of the composites, The morphology structures of the composites were observed by scanning electron microscope (SEM) , the compatibility among various components in composites were studied by infrared spectrum analysis (IR), dynamic thermal mechanical analysis (DMA) and X-ray photoelectron spectroscopy (XPS). The results showed that the best coupling agent was KH550 and the content was 2.5 phr ( parts per hundred rubbers ). The basalt fibers treated with KH550 combined with silicone rubber and formed new chemical bond, indicating the coupling agent KH550 improved the compatibility among various components in composites.     

有机硅密封胶粘接聚烯烃材料的研究

研究了不同类型的有机硅密封胶对PE、PP材料的粘接性能,结果表明交联剂和界面因素是影响有机硅密封胶粘接性能的主要因素。根据研究结果设计合成自催化交联型有机硅密封胶和有机硅复合密封胶,并研究它们的性能。     

Effect of KH550 on the Preparation and Compatibility of Carbon Fibers Reinforced Silicone Rubber Composites

Silicone rubber has good heat resistance, but its mechanical properties are poor. To improve the mechanical properties of the silicone rubber, the carbon fiber / silicone rubber composites were prepared in this paper, in which the silicone rubber was used as the matrix, the high-performance carbon fiber (CF) treated with coupling agent is used as the reinforcement. The best composite formulation, the types and content of coupling agent are determined by testing mechanical properties of the composites. The morphology structures of the composites were observed by scanning electron microscope (SEM), the compatibility between carbon fiber and silicone rubber was studied by infrared spectrum analysis (IR), dynamic thermal mechanical analysis (DMA) and X-ray photoelectron spectroscopy (XPS). The results show that the best composite formulation is silicone rubber of 100 phr, carbon fiber of 12 phr, coupling agent KH550 of 2.5 phr. The best first curing conditions are at 175 ^°C under 10 MPa for 30 min, the postcuring conditions are at 200 ^°C for 2h. The compatibility between carbon fiber treated with KH550 and silicon rubber is the best by SEM, IR, DMA and XPS analysis, and confirm that the coupling agent KH550 plays a compatilizer role in the preparation process of the carbon fiber/silicone rubber composites.     

有机硅密封胶中裂解硅油的检测

配制了含裂解硅油的有机硅密封胶和含二甲基硅油的有机硅密封胶,分别测定其力学性能、热性能;并用四氢呋喃浸泡有机硅密封胶,过滤后将滤液进行凝胶渗透色谱（GPC）和硅核磁共振（^29Si NMR）分析。结果显示,与含二甲基硅油的有机硅密封胶相比,含裂解硅油的有机硅密封胶经水紫外、高温老化后的拉伸强度和拉断伸长率下降幅度更大,热分解温度更低;其浸出液的摩尔质量分布更宽,有4个峰存在,且29Si NMR谱图中存在M、D、T链节的特征吸收峰。通过力学性能、热性能测试,再经^29Si NMR和GPC分析,可定性检测有机硅密封胶是否含裂解硅油。     

国内建筑用密封胶的研究进展

对比聚硫型、硅酮型、聚氨酯型密封胶的性能特点,从单组分密封胶和双组分密封胶两个角度综述了国内近几年的研究进展,并介绍了密封胶在建筑等行业的应用。     

有机硅密封胶的结构和性能（Ⅱ）

有机硅密封胶广泛应用于工业领域的粘接密封，为了系统地研究有机硅密封胶的结构-性能，采用甲基三甲氧基硅烷等4种不同结构的交联剂，设计合成了4种有机硅密封胶。通过测定4种不同结构的有机硅密封胶的拉伸强度、剪切强度和剥离强度，并采用线性回归方法研究了交联剂对有机硅密封胶的力学性能、粘接性能的影响。结果表明，交联密度与密封胶的硫化胶的拉伸强度有很好的线性相关性，交联密度是影响密封胶粘接强度和粘接功的重要因素。     

双组分脱醇型有机硅密封胶的研制

研制了车灯用双组分脱醇型有机硅密封胶,讨论了交联剂和偶联剂对密封胶性能的影响。结果表明选用四官能的交联剂有助于提高硅橡胶的力学性能。采用不同的偶联剂进行搭配可获得对PC、PVC、ABS、PA、玻璃和铝等多种材质的优异粘接性能。     

Dual lamellar crystal structure in poly(vinylidene fluoride)/acrylic rubber blends and its biaxial orientation behavior

The miscibility for melt-mixed poly(vinylidene fluoride) (PVDF)/acrylic rubber (ACM) blends and the crystal morphology of PVDF in the blends were investigated over the whole composition ranges by dynamic mechanical analysis (DMA), wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). DMA measurements revealed that PVDF is miscible with ACM in ACM-rich system, and partially miscible in PVDF-rich system. Two kinds of PVDF lamellar structures with different long periods were detected by SAXS and TEM for the partially miscible blends. In the miscible system, only one kind of crystal lamellae with enlarged long period is found. The two kinds of lamellar structures in the blend show different orientation behavior during the uniaxial stretching to result in a biaxial orientation. The lamellae with short long period are oriented vertical to the stretching direction, while those with large long period were found to be oriented parallel to the stretching direction.     

Structure-property behavior of segmented polyurethaneurea copolymers based on an ethylene-butylene soft segment

Novel segmented polyurethaneurea copolymers were synthesized using a poly(ethylene-butylene) glycol based soft segment and either hydrogenated diphenyl methane diisocyanate (HMDI) or hexamethylene diisocyanate (HDI) in addition to either ethylene diamine (EDA) or 2-methyl-1,5-diaminopentane (DY) as the chain extender. Dynamic mechanical analysis (DMA), small angle X-ray scattering (SAXS) and in some cases atomic force microscopy (AFM) established the presence of a microphase-separated structure in which hard microdomains are dispersed throughout a soft segment matrix. Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) imply that the materials are amorphous. Samples that are made with HMDI/DY and have hard segment contents in the range of 16-23 wt% surprisingly exhibit near-linear mechanical deformation behavior in excess of 600% elongation. They also show very high levels of recoverability even though their hysteresis is also considerable. The materials have all proven to be melt processable in addition to solution processable.     

硅酮胶密封的中空玻璃

中空玻璃的边缘密封系统的主要功能是将两片或多片玻璃结构性黏结起来防止水汽进入.通过双重边缘密封系统可以取得最好的密封效果,在该系统中,第一道密封是由聚异丁烯基密封胶提供水汽密封,第二道弹性密封则确保中空玻璃在相应荷载下的结构整体性.硅酮双重密封的中空玻璃比有机胶密封的中空玻璃具有较低的水汽渗透率,因为边缘密封的渗透性几乎完全由第一道密封(PIB)的渗透性决定,并且因为硅酮第二道密封在阻止水汽扩散进入第一道密封方面比有机胶表现得更好.     

我国有机硅结构密封胶发展现状与展望

介绍了玻璃幕墙的特点及有机硅结构密封胶的功能、发展历史与最新进展,对国内外几种典型的有机硅结构密封胶性能进行了分析比较,对有机硅结构密封胶的前景进行了展望并提出了发展建议。     

Polymer electrolyte membranes from fluorinated polyisoprene-block-sulfonated polystyrene: Structural evolution with hydration and heating

Small-angle neutron scattering (SANS) and ultra-small-angle X-ray scattering (USAXS) have been used to study the structural changes in fluorinated polyisoprene/sulfonated polystyrene (FISS) diblock copolymers as they evolved from the dry state to the water swollen state. A dilation of the nanometer-scale hydrophilic domains has been observed as hydration increased, with greater dilation occurring in the more highly sulfonated samples or upon hydration at higher temperatures. Furthermore, a decrease in the order in these phase separated structures is observed upon swelling. The glass transition temperatures of the fluorinated blocks have been observed to decrease upon hydration of these materials, and at the highest hydration levels, differential scanning calorimetry (DSC) has shown the presence of tightly bound water. A precipitous drop in the mechanical integrity of the 50% sulfonated materials is also observed upon exceeding the glass transition temperature (T_g), as measured by dynamic mechanical analysis (DMA).     

有机硅材料在航天工业的应用

介绍了有机硅材料（包括硅橡胶、硅树脂、硅脂等）在航天工业的应用现状。     

硅氧烷改性聚氨酯密封胶的研究

利用硅氧烷封端对聚氨酶进行改性得SPU预聚体，进而制备出硅烷化聚氨酯密封胶，然后对其性能进行了测试并与其他产品进行对比。结果表明：改性后的产物在粘接性、耐热性、耐湿热性、贮存稳定性及某些力学性能上综合了硅酮和聚氨酶的优点，又避免了各自的部分缺点。是一种新型建筑密封材料。     

Hygrothermal cycling effects on the durability of phenolic based composites

Work has been performed to investigate the thermal and mechanical properties of carbon fiber/phenolic resin composites as engineering materials for the aerospace industry. These materials are cost effective while displaying excellent temperature and fire resistance as well as good mechanical properties. All phenolic and epoxy composite specimens used here were prepared by resin transfer molding (RTM) to model a cost‐effective process. Hygrothermal cycling effects on the property changes of phenolic composites were evaluated through thermal, mechanical, and morphological tests. The fracture performance of a phenolic composite modified with a silicone‐based additive decreased after fewer hygrothermal cycles than unmodified phenolic and epoxy composites. Results from dynamic mechanical analysis (DMA) experiments showed that the modified phenolic composite was more significantly affected by the hygrothermal cycling than the unmodified phenolic composites. Fatigue tests showed that the phenolic composites that were not exposed to hygrothermal cycling had more resistance to fatigue cycles than the epoxy composites.     

Development of an electrochemical impedance spectroscopy sealant test: I. Nonconductive sealants

Distinguishing between sealants and providing laboratory prognostic tools is essential for qualifying new sealants. Current test methods do not provide adequate discrimination between sealants. A laboratory test based on electrochemical impedance spectroscopy (EIS) supplemented by adhesion strength measurements and examination of sealed, bimetallic surfaces has been developed to give an early indication of sealant performance. Specimens using one of two different nonconductive sealants underwent hot-salt-water exposure followed by EIS measurements, pull strength measurements, and visual inspection. Defective sealant bonded specimens were readily detected by EIS. Absorption of moisture by the sealants was also detected and quantified.     

有机硅密封剂高温力学性能研究

在温度25~250℃对3类硫化体系的5种有机硅密封剂的拉伸强度、180o剥离强度和剪切强度的研究表明:随着温度的升高,5种有机硅密封剂的拉伸强度、180o剥离强度和剪切强度均不断下降,其中拉伸强度和剪切强度降低的速率递减。有机硅密封剂的高温性能变化与硫化体系类型密切相关,脱氢硫化体系HM321密封剂在25~150℃拉伸强度、剪切强度和180o剥离强度均最高,但在25~250℃拉伸强度、剪切强度和180o剥离强度保持率均最低。脱氨硫化体系XY-602S有机硅胶粘剂在232~250℃的拉伸强度和剪切强度最高,25~250℃的拉伸强度保持率也最高。     

Resistance to fire of intumescent silicone based coating: The role of organoclay

The fire performance of a curable-silicone based coatings containing expandable graphite (EG) and an organoclay is evaluated in hydrocarbon fire scenario (standard UL1709) using a lab-scale furnace test. It is shown that the use of organoclay allows achieving better performance. The influence of the clay as additional filler is investigated on the fire performance and on the mechanical properties of the char. It is shown that the clay increases significantly the mechanical properties of the char and hence, the fire performance of the silicone based coating. In a next part, the silicone/clay material was characterized by electron microscopy, wide-angle X-ray scattering and solid state ²⁹Si nuclear magnetic resonance (NMR). It evidences the nanodispersion of the clay into the silicone matrix and two main interactions: (i) intercalation of some silicate layers and (ii) chemical reactions between the hydroxyl groups of the clay and the silicone matrix. Finally, X-ray fluorescence of the residue after fire testing shows the organoclay is present uniformly throughout the thickness of the char, due to the previous interaction, and hence increasing the cohesion of the char.     

Development of an electrochemical impedance spectroscopy sealant test: II. Conductive sealants

Distinguishing between sealants and providing laboratory prognostic tools is essential for qualifying new sealants. Current test methods do not provide adequate discrimination between sealants. A laboratory test based on electrochemical impedance spectroscopy (EIS) supplemented by adhesion strength measurements and examination of sealed, bimetallic surfaces is an approach for discriminating between sealants. This approach gives an early indication of sealant performance so that suitable materials can be chosen for aircraft and other applications. Sealant specimens (three conductive sealants) underwent hot-salt-water exposure followed by EIS inspection, pull strength measurements, and visual inspection. Several specimens exhibited a temporary loss of conductivity during exposure. The maximum low-frequency impedance was correlated to both corrosion inside the sealant ring and pull strength.