Thermal Degradation of Polysiloxane Coatings on E-Glass Fiber. A FTIR Study

Fourier Transform Infrared Spectroscopy and Thermal Analysis have been used to study the thermal and termooxidative degradation of polysiloxane coatings obtained by treating E-glass fiber with aqueous solutions of 3-chloropropyltriethoxysilane. Initial weight losses were due to polymerization of the coatings. Severe oxidative degradations were observed at temperatures above 180°C. At 550°C the residue of the coating was found to be silica with free silanol groups.     

Synergism of polysiloxane and zinc borate flame retardant polycarbonate

Liquid polysiloxane (PSI) and zinc borate (ZB) were combined for the flame retardance of polycarbonate (PC). During polymer combustion, for the PC flame-retarded with PSI only, PSI can form char residue containing silica on the material surface. But the liquid silicone tends to drip with melting polymer and volatilize in high temperature, thus decreasing the charring performance. In the case of only ZB flame retardant involved, this inorganic flame retardant and possible some of its decomposition products (B₂O₃) more difficultly move to the surface and it appears that they do not effectively contribute to the char formation. Present study suggests that the existing synergism between PSI and ZB is the result of chemical reaction via forming cross-linking B–O–Si structure. As results, the loss of Si/silicone is reduced by eliminating the melt dripping. Meanwhile, boron species can be “dragged” by PSI (in the form of borosiloxane) to the surface of the char residue. Consequently, Si and B elements together contribute to the integrity of char residue layer with better quality, achieving obviously improved flame retardance compared with only PSI and only ZB flame retardant systems.     

大环聚硅氧烷分子

聚硅氧烷是一种重要的高分子材料,其优良的物理化学性能使其在化工、冶金、建筑等众多领域具有广泛的应用,由于缺少链端基,环状聚硅氧烷这种特殊的空间结构使其具有尤为特定的性质和应用性能.本文主要简述了环状聚硅氧烷相比一般线形聚硅氧烷所具有的本体、溶液和化学特性.因为聚二甲基硅氧烷是硅氧烷中最主要的一种,所以本文主要对大环聚二甲基硅氧烷的合成方法和基本性质进行了综述,并介绍了大环聚硅氧烷的应用方向,主要是在拓扑嵌入、形成索烃和聚轮烷等方面的应用.     

PMPS/PMAc相容性与同步互贯聚合物网络的阻尼性能研究

互贯聚合物网络是一种聚合物合金 ,其组分的热力学性质决定组分间的相容性和微相结构 ,从而影响材料的阻尼性能 .采用同步互贯聚合物网络 (SIN)技术制备了一种新型的聚苯基硅氧烷 (PMPS) 聚甲基丙烯酸酯 (PMAc)阻尼材料 ,用DMA和AFM等表征研究了其玻璃化温度转变行为与微观相态结构 .结果表明 ,由相容性好的组分制备的SIN材料阻尼值最高 ,tanδmax 可达 1 4,只有一个玻璃化温度转变峰 ,其微相结构为双相连续 ;组分介于相容与不相容之间时 ,所构成的SIN样品的tanδ≥ 0 3的温度区间最宽 ,可达 170℃ ,微相结构为单相连续 ;由相容性差的组分制得的SIN阻尼材料的内耗峰裂分为两个区间 .PMPS PMAcSIN材料的阻尼性能可以通过调节组分的相容性进行控制 .     

Aminopropyl-modified silica as cross-linkers of polysiloxane containing γ-chloropropyl groups for preparing heat-curable silicone rubber

A series of aminopropyl-modified silica (APS) with different amine contents was prepared and, subsequently, used as cross-linkers of polysiloxane containing γ-chloropropyl groups (CPPS) to prepare heat-curable silicone rubber (MCSR). The dispersion of APS in polysiloxane matrix was studied by scanning electron microscopy. The curing characteristics, mechanical and thermal properties of the MCSR were analyzed by a rheometer, mechanical testing and thermal gravimetric analysis (TGA), respectively. The effects of the silica (TS530) content and the molar ratio of APS/CPPS on the curing characteristics were studied. The influence of the amounts of TS530 and APS, and the kind of APS, on the comprehensive mechanical properties of MCSR is discussed. The optimized conditions to prepare MCSR were obtained as follows: the amount of TS530, 55 parts per hundreds of polysiloxane in weight; the molar ratio of [NH]/[γ-chloropropyl], 1.5: 1; and the amount of amino groups on the surface of APS, 0.65 mmol/g. Additionally, TGA results show that MCSR has high thermal stability.     

Ion conductive characteristics of cross-linked network polysiloxane-based solid polymer electrolytes

A series of cross-linked network polysiloxanes containing oligoethylene oxide units, (OCH₂CH₂)_n, as internal free chains have been synthesized by performing hydrosilylation of partially PEO-substituted polysiloxane precursor with , ω-diallyl terminated poly(ethylene glycol). The polymer electrolytes were formed by complexing with LiN(CF₃SO₂)₂ electrolyte salt and exhibited superior conductive property. The σ_RT of the network polymer electrolytes is in the range of 2.50×10⁻⁵ to 1.62×10⁻⁴ S/cm and depends on the cross-linking density (in terms of Si–H amount of the siloxane precursor), repeating unit number of internal oligoethylene oxide and chain length of the cross-linker. The significant enhancement of the conductivity was observed when low molecular weight dimethyl poly(ethylene glycol) was added as plasticizer. The temperature dependence of the ionic conductivity was also studied, following the Vogel–Tamman–Fulcher (VTF) equation.     

SYNTHESIS OF LINEAR POLYSILOXANE WITH PENDANT BENZO－15－C－5 MOIETIES AND ITS TRANPORT PROPERTIES IN BULK LIQUID MEMBRANE SYSTEM

ＳＹＮＴＨＥＳＩＳＯＦＬＩＮＥＡＲＰＯＬＹＳＩＬＯＸＡＮＥＷＩＴＨＰＥＮＤＡＮＴ　ＢＥＮＺＯ－１５－Ｃ－５ＭＯＩＥＴＩＥＳＡＮＤＩＴＳＴＲＡＮＰＯＲＴＰＲＯＰＥＲＴＩＥＳＩＮＢＵＬＫＬＩＱＵＩＤＭＥＭＢＲＡＮＥＳＹＳＴＥＭＣＨＥＮＹｕａｎｙｉｎ；Ｌｕ...     

聚氰丙基甲基硅氧烷-聚脲嵌段共聚物的NMR表征及研究

用高分辨NMR对聚甲基硅氧烷-聚脲嵌段共聚物以及聚氰丙基甲基硅氧烷-聚脲嵌段共聚物结构进行表征,对NH形成的各种氢键进行详细的研究,同时观察了氢键在力学性能中的作用,结果发现氢键强烈地影响着力学性能。用固体¹H宽线研究这类材料的相分离状况,并总结影响相分离的因素。保持硬段含量不变,增加软段分子量使相分离程度增加;保持软段分子量不变,增加硬段含量使相分离程度降低。软、硬段之间的相互作用(如氢键)使相分离程度降低。     

以对-(4-烯丙氧基苯甲酰氧基)苯甲酸对-甲氧基苯酚酯为单体的液晶聚硅氧烷的合成与表征

侧链型液晶聚合物是目前很有兴趣的研究课题之一。在国内,有关的研究报道也逐渐增多,本工作设计并合成了对-(4-烯丙氧基苯甲酰氧基)苯甲酸对-甲氧基苯酚酯单体,其结构式为:     

含氨基酸侧链的有机硅高分子催化剂 ⅩⅤ.γ-(L-酪氨酰胺基)丙基硅氧烷钯催化剂的合成加氢活性及其结构表征

本文报导了四种不同N/Pd摩尔比的聚γ-(L-酪氨酰胺基)丙基硅氧烷钯催化剂的合成及其催化加氢活性,这类催化剂与聚γ-((L-酷氨酸)丙基硅氧烷钯催化剂相比较,虽然均具有类似的N→Pd配位的活性中心组成,但它们对底物的加氢活性则明显不同,前者对丙烯腈、丙烯酸、环己烯和1-癸烯的催化活性比后者高,对苯乙烯则相反。N/Pd摩尔比、反应温度、溶剂以及体系的pH值对催化活性的影响,两者的情况大致相同,标题催化剂对衣康酸的催化加氢,产物的光学纯度为30％。