Characterization of barium titanate reinforced acrylonitrile butadiene rubber composites for flexible electronic applications: influences of barium titanate content

The aim of this study was to develop high dielectric constant flexible polymers with a highly efficient and cost‐effective approach using acrylonitrile butadiene rubber (NBR) as the polymer matrix and barium titanate (BT) as the high dielectric constant filler. The BT powder was synthesized with a solid‐state reaction and was characterized using a particle size analyzer, XRD, SEM and Fourier transform infrared spectroscopy. NBR/BT composites were fabricated using an internal mixer with various BT loadings up to 160 phr. The influence of BT loading on the cure characteristics and mechanical, dynamic mechanical, thermal, dielectric and morphological properties was determined. The incorporation of BT in the NBR matrix shortened scorch time and increased delta torque. The mechanical properties, thermal stability and dielectric constant were greatly improved and increased with BT loading. The results suggest that the reinforcement effect was achieved due to strong hydrogen bonding or polar–polar interactions between NBR matrix and BT filler. This is further corroborated by the good dispersion of BT filler in the NBR matrix observed with SEM imaging. These findings can be applied to produce high‐performance dielectric elastomers. © 2020 Society of Industrial Chemistry     

Monte Carlo simulation of gas phase polymerization of 1,3‐butadiene. Part II: Kinetics optimization and confirmation

Studies on the deactivations and initiations of gas phase polymerizations of 1,3‐butadiene have been achieved by Monte Carlo simulation. Initiation and deactivation control the reaction before and after the peak of the polymerization rate, respectively. The influence of polymerization temperature has been studied. Monte Carlo modeling of polymerization kinetics and mechanism was confirmed by the agreement of experimental data and simulation results of polymerizations run with a temporary evacuation of monomer. The balance of catalysts and active chains is established by both initiation and chain transfer reactions with cocatalyst, which causes a ‘pseudo‐stability’ stage. © 2003 Society of Chemical Industry     

聚合物载体－稀土金属络合物的研究 ⅩⅢ．聚［苯乙烯－甲基丙烯酸β（甲基亚硫酰基）乙酯］的结构与其稀土金属络合物催化丁二烯聚合的活性

从测得的竞聚率计算了单体链节在聚［苯乙烯－甲基丙烯酸β（甲基亚硫酰基）乙酯］（ＰＳＭ）中的序列分布。苯乙烯（Ｓ）或甲基丙烯酸β（甲基亚硫酰基）乙酯（Ｍ）的长序列的概率随着ＰＳＭ中相应单体含量的增加而增加。对于Ｓ和Ｍ摩尔分数大致相等的ＰＳＭ，单体链节的长序列分布函数值相接近。用与此结构相近的ＰＳＭ合成的稀土金属络合物，其催化活性不佳。在Ｍ短序列分布和Ｓ长序列分布较高的情况下，络合物的催化活性最好。所得聚丁二烯的微观结构与ＰＳＭ中单体单元的分布无关。     

Synthesis and physicochemical characterization of a well-defined poly(butadiene 1,3)-block-poly(dimethylsiloxane) copolymer

For the first time, order-order and order-disorder transitions were detected and characterized in a model diblock copolymer of poly(butadiene-1,3) and poly(dimethylsiloxane) (PB-b-PDMS). This model PB-b-PDMS copolymer was synthesized by the sequential anionic polymerization (high vacuum techniques) of butadiene 1,3 (B) and hexamethylciclotrisiloxane (D₃), and subsequently characterized by nuclear magnetic resonance (¹H and ¹³C NMR), size exclusion chromatography (SEC), Fourier Transform infrared spectroscopy (FTIR), Small-Angle X-ray scattering (SAXS) and rheology. SAXS combined with rheological experiments shows that the order-order and order-disorder transitions are thermoreversible. This fact indicates that the copolymer has sufficient mobility at the timescale and at the temperatures of interest to reach their equilibrium morphologies.     

用复合烷基锂引发丁二烯聚合

对以环己烷为溶剂、四氢呋喃为微观结构调节剂、复合烷基锂为引发剂的丁二烯聚合反应过程进行了研究，考察了不同引发温度、不同配比的复合烷基锂对聚合反应的影响，并与以正丁基锂为引发剂的丁二烯聚合反应过程进行了比较。     

NdCl_3·nTBP/MgCl_2-AlR_3催化体系合成丁二烯橡胶

探讨了以NdCl_3的磷酸三丁酯(TBP)溶液为主催化剂、烷基铝为助催化剂、MgCl_2为载体组成的Ziegler-Natta型催化体系引发丁二烯(Bd)聚合的某些规律。用AlEt_3作助催化剂,聚合物的顺1,4-结构含量仅为57％,反1,4-结构含量为42％;而以Al(i-Bu)_3作助催化剂,聚合物的顺1,4-结构含量为88％,反1,4-结构含量为11％。各种陈化体系中,以NdCl_3·nTBP/MgCl_2-Al(i-Bu)_3-Ip三元体系的催化活性最高,当Nd/Bd(摩尔比)为7×10~(-5)时,单体转化率达80％。低温聚合可获得高顺式、高分子量聚合物。     

Short fibre elastomer composites: effect of fibre length,orientation, loading and bonding agent

A series of short fibre reinforced styrene butadiene rubber (SBR) composites were prepared by incorporating sisal fibres of different lengths and different concentrations. The vulcanization behaviour and the properties of the vulcanizates were measured by the relevant ASTM procedures. The processing characteristics such as green strength and mill shrinkage were improved by the addition of fibres. The properties like tensile strength, tear strength, moduli at 10% and 20% elongations were found to be maximum for composites containing longitudinally oriented fibres of length 6 mm. Mixes containing 35 phr loading of fibres and bonding agent showed better mechanical performance than others. The failure behaviour of tensile and tear specimens have been analysed by scanning electron microscopy techniques. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

On the specific reactivity of platinum segregated layers on Pt80X20 (111) (X= Ni,Co, Fe) alloys

The influence of alloying of Pt with 20 at.% of Ni, Co and Fe has been studied in the hydrogenation of 1,3 butadiene. Iron induces the more important modifications, with both higher activity and selectivity. The results are discussed in terms of the surface segregation, the local order in surface and the electronic properties measured by photoemission of core levels.     

不同牌号丁苯橡胶的耐低温性能研究

研究3种牌号丁苯橡胶(SKMS-10,SL-4525-0,SBR1502)的硫化特性、物理性能和耐低温性能。结果表明:SKMS-10具有优异的耐低温性能,生胶的玻璃化转变温度(T_g)为-73.3℃,硫化胶的T_g为-59.8℃,适于在极寒条件下使用;SL-4525-0胶料的F_max-FL较大,硫化胶的拉伸强度为19.3 MPa,撕裂强度为53 kN·m^-1,T_g为-48.6℃,具有优异的综合性能;SBR1502硫化胶的拉伸强度高达24.9 MPa,撕裂强度为49 kN·m^-1,但T_g为-38.4℃,耐低温性能较差,适用于载荷较大且耐低温性能要求不高的橡胶减振制品。