树枝状碳硅烷涂层电色谱柱的制备及其评价

利用碳硅烷树枝状大分子末端SiCl键的高反应活性和多官能团性,将β-环糊精固定到毛细管柱上,制备了一种新型的手性毛细管电色谱柱。本涂层柱性能稳定,使用寿命长,经过1个月的连续运行,柱效能损失率低于5%。优化分离条件,采取16kV分离电压、检测波长214nm、10cm位差进样7s和40mmol/L磷酸盐缓冲体系,分离扑尔敏、盐酸异丙嗪和苯丙胺手性异构体,其中G2P代柱子对扑尔敏分离柱效达到2.5×105Plates/m,分离度RS=1.43,基线分离,取得了较满意的分离效果。     

硅橡胶/氟橡胶并用胶的制备及力学性能

硅橡胶和氟橡胶作为国防、航天等重要领域的耐热材料一直被人们青睐,但其有着各自地优缺点且价格昂贵,本文尝试将这两种橡胶制成并用胶以解决氟橡胶不耐低温和加工性差的问题,以期增大其使用温度范围。采用机械共混法制备硅橡胶/氟橡胶并用胶,研究了硅橡胶和氟橡胶的混炼工艺、并用比、共硫化体系和硫化条件对并用胶力学性能的影响。结果表明,当硅橡胶/氟橡胶的质量比为10∶90,共硫化体系为3~#硫化剂/过氧化二异丙苯(DCP),一段硫化温度为170℃、硫化压力为10MPa、硫化时间为30min,二段硫化温度为200℃、硫化时间为6h时,并用胶的力学性能达到最好。     

Hydrophilicity Modification of Addition-cured Room Temperature Vulcanization Silicone Rubber

Allyl terminated polyether was used to improve the hydrophilicity of addition-cured room temperature vulcanization silicone rubber. With the increasing of the polyether, both the hydrophilicity and water absorbed of the vulcanizates were increased. The mechanical properties were also improved by adding the polyether. The result showed that 1.5wt% of the polyether provided the silicone rubber with proper hydrophilicity.     

Synthesis of Novel Carbosilane Dendrimers with Myo—inositol Cores

The preparation of carbosilane dendrimers with cores of myo-inositol and the outmost periphery grougs of allyl groups has been reported.By using alternate hydrosilylation and alkenyiation reactions,the dendrimer have been carried up to the third generation with 48 allyl groups on the periphery.     

Simultaneous Enhancement of Mechanical and Dynamic Mechanical Properties of Natural Rubber/Recycled Ethylene-Propylene-Diene Rubber Blends by Electron Beam Irradiation

Mechanical and dynamic mechanical properties of natural rubber/recycled ethylene-propylene-diene rubber (NR/R-EPDM) blends were simultanoeusly enhanced by electron beam (EB) irradiation. The cross-linking promoter, trimethylolpropane triacrylate (TMPTA), was also introduced into the blends to induce the cross-linking. By applying EB irradiation, the tensile modulus, hardness, swelling, cross-link density, and storage modulus increased with increase in the irradiation dose; an irradiation dose of 50 kGy was efficient to gain optimum tensile strength. The formation of irradiation-induced cross-links after EB irradiation is a major concern for the enhancement of mechanical, swelling resistance, and dynamic mechanical properties of the blends.     

橡胶木粉填充LLDPE复合材料的结构和力学性能

用橡胶木粉填充线性低密度聚乙烯(LLDPE),研究了酸、碱溶液预处理木粉的效果和硅烷偶联荆(KH-570)、MMA接枝的天然橡胶胶乳(MGL-30)两种改性剂对橡胶木粉表面改性的效果,以及未粉粒径和填充量等对木粉／LLDPE复合材料力学性能的影响,并用SEM对复合材料拉伸断面的形态结构进行了分析。结果表明：木粉的拉径、木粉填充量和改性荆用量对复合材料的力学性能有较大的影响,经碱溶液预处理再用改性荆改性后的木粉能有效地改善木粉与LLDPE的界面粘结强度,提高橡胶木粉／LLDPE复合材料的力学性能。     

导电硅橡胶理论研究进展

综述了导电硅橡胶的理论研究进展，包括导电通路的形成以及体系的电学性能。并讨论了该领域有待于入研究的问题。     

Effect of Ground Rubber Powder on Properties of Natural Rubber

Ground rubber powder (GRP) with three different sizes was incorporated into nature rubber matrix with different loading. Cure characteristics, swelling behaviour, crosslink density, tensile fractured surface, and mechanical properties have been studied. Based on the cure characteristics, it is evident that the processability of the rubber compounds has not changed obviously with the different GRP loading. The introduction of GRP in virgin rubber leads to the increase in swelling degree and the decrease in crosslink density. Tensile strength, hardness and abrasion resistant deteriorate with the increase of GRP loading, but the tear resistance gets better. If the ground rubber particles are smaller, the properties are more similar to the virgin rubber. Because of the phase separation of the GRP and matrix, the properties get worse with the bigger ground rubber powder.     

加成型液体硅橡胶的研究进展

结合加成型液体硅橡胶的硫化原理,综述了加成型液体硅橡胶导热性能、耐高温性能及粘结性能的最新研究进展,发现加入金属氮化物导热填料是提高加成型液体硅橡胶导热性能的有效途径;改善分子结构是提高加成型液体硅橡胶耐高温性能的主要途径;共混粘结促进剂是提高加成型液体硅橡胶粘结性能的重要途径。介绍了加成型液体硅橡胶的最新应用领域,提出功能化加成型液体硅橡胶,如3D个性化打印硅橡胶、人体器官硅橡胶、高折光封装硅橡胶等功能材料是未来加成型液体硅橡胶的发展方向。     

A New Strategy to Exfoliate Silicone Rubber/Clay Nanocomposites

Summary: A new strategy was developed to prepare disorderly exfoliated nanocomposites, in which a soft siloxane surfactant with a weight‐average molecular weight ( ) of 1 900 was adopted to modify the clay. The modified clay slurry was then mixed with silicone rubber by hand, and exfoliation was achieved. The proposed mechanism thereof was verified by TEM and XRD. The physical entanglement of the soft siloxane surfactant plays a vital role in the diffusion and intercalation of the matrix molecules during the compounding of the slurry‐polymer mixture. This simple method is applicable to other silicone‐based materials reinforced by clay.

TEM micrograph of silicone rubber/clay‐sil nanocomposite.     

Reliable Condensation Curing Silicone Elastomers with Tailorable Properties

The long-term stability of condensation curing silicone elastomers can be affected by many factors such as curing environment, cross-linker type and concentration, and catalyst concentration. Mechanically unstable silicone elastomers may lead to undesirable application failure or reduced lifetime. This study investigates the stability of different condensation curing silicone elastomer compositions. Elastomers are prepared via the reaction of telechelic silanol-terminated polydimethylsiloxane (HO-PDMS-OH) with trimethoxysilane-terminated polysiloxane ((MeO)₃Si-PDMS-Si(OMe)₃) and ethoxy-terminated octakis(dimethylsiloxy)-T8-silsesquioxane ((QM^OEt)₈), respectively. Two post-curing reactions are found to significantly affect both the stability of mechanical properties over time and final properties of the resulting elastomers: Namely, the condensation of dangling and/or unreacted polymer chains, and the reaction between cross-linker molecules. Findings from the stability study are then used to prepare reliable silicone elastomer coatings. Coating properties are tailored by varying the cross-linker molecular weight, type, and concentration. Finally, it is shown that, by proper choice of all three parameters, a coating with excellent scratch resistance and electrical breakdown strength can be produced even without an addition of fillers.     

Synthesis of Carbosilane Dendrimers Containing up to Four Metal Layers

Onion structures : Carbosilane dendrimers containing up to four metal layers have been constructed (see picture). The metal layers are linked by di‐ or tritopic N,P ligands. Selective deconstruction of the dendrimers is achieved by using salts of chloride or iodide anions.

     

真空紫外辐照对加成型硅橡胶光学性能的影响

考察了加成型硅橡胶在真空环境中经1000ESH紫外辐照后的性能变化。结果表明,辐照后材料均出现发黄的现象,光学透过率大幅度 下降,同时加入硅酸钾包覆后制备的热控涂层反射率下降。经原位测试与离位测试,发现加成型硅橡胶在两种不同条件下测得的结果差异较小,而在有机硅橡胶中加入ZnO后原位与离位测试结果则差异明显,表现出明显的漂白作用。     

硅橡胶硫化反应场的数值模拟

以化学反应动力学原理为基础,实验确定了硅氢加成反应的动力学模型;引入 了硫化率增量的概念,获得了全量硫化率和硫化率增量的数值计算式;根据统计理 论,获得了起始分子无规分布时的交联结构参数的数值计算式;介绍了非稳态硫化 反应场的有限元模拟步骤。在此基础上,设计了硅橡胶硫化反应过程的有限元模拟 软件;应用该软件,根据输入的初边值条件,可计算任一空间点在任一时刻的交联 反应参数和交联结构参数,进而可预测制品性能、优化反应参数,或优化设计高分 子材料。最后给出了一个典型算例,并实验验证了该模拟理论及算法的合理性。     

橡胶活性官能团对增韧环氧树脂动态力学性能的影响

用动态扭摆法测试聚丙烯酸丁酯橡胶增韧环氧树脂的动态力学行为,研究在环氧树脂低固化度和高固化度时,橡胶活性官能团种类(环氧基官能团与羧基官能团)和数量(官能度)对其影响。研究体系中橡胶玻璃化转变温度(Tg)的移动大小,与橡胶和基体树脂健合程度之间的关系。     

硅树脂/硅橡胶杂化膜的制备及性能研究

以十三氟辛基三乙氧基硅烷、四甲基二乙烯硅氧烷、乙烯基三甲氧基硅烷和正硅酸乙酯为原料,通过水解缩合制备了乙烯基含氟硅树脂。乙烯基硅橡胶和乙烯基含氟硅树脂为基质材料,含氢硅油为交联剂,硅氢加成制备了改性硅橡胶杂化膜材料。透气性能测试表明,当含氟硅树脂质量分数50.0%时,膜的成膜性和富氧性能之间达到最佳平衡点,30℃和0.01 MPa压差下,P（O2）为628 Barre,a（O2/N2）为3.36。与普通乙烯基硅橡胶交联膜比,这种有机―无机杂化膜在保持原有氧气透过系数的基础上,较好的改进了氧氮分离性能。     

可瓷化硅橡胶材料的研究

研究了一种可瓷化硅橡胶,其特点是在火灾发生时可在金属线外形成瓷化绝缘保护层,600℃的成瓷温度大幅度低于目前文献报道的成瓷温度。实验得到的优化瓷化填料配方为:相对于100份混炼胶,氧化铝10份、硅灰石15份、结构控制剂9份、碳酸锂3份。在此配方条件下,未瓷化硅橡胶的断裂伸长率316%、拉伸强度10.79MPa、体积电阻率134×10~(12)Ω·cm,其在600℃、800℃瓷化后的抗压强度分别为3.47MPa、10.13MPa、体积电阻率≥28×10~(12)Ω·cm,满足电缆用硅橡胶的力学和绝缘要求。经热重分析及SEM分析可知加入瓷化填料后,试样烧蚀重量减少了39.4%,烧蚀残留率大大提高,且成瓷试样结构致密。     

填充粒子对复合型导电硅橡胶电阻温度特性的影响

研究了炭黑填充复合型导电硅橡胶的电阻温度特性,分析了升温过程中导电硅橡胶电阻特性的详细变化过程。研究了导电粒子和白炭黑含量对导电硅橡胶电阻温度特性的影响,测量了在不同热处理温度下电阻率的变化及加力时电阻的驰豫时间。分析了热处理对电阻特性影响的机理。