Multilayer graphene/chlorine‐isobutene‐isoprene rubber nanocomposites: the effect of dispersion

Multilayer graphene (MLG) is composed of approximately 10 sheets of graphene. It is a promising nanofiller just starting to become commercially available. The dispersion of the nanofiller is essential to exploit the properties of the nanocomposites and is dependent on the preparation method. In this study, direct incorporation of 3 parts per hundred of rubber (phr) MLG into chlorine‐isobutene‐isoprene rubber (CIIR) on a two‐roll mill did not result in substantial enhancement of the material properties. In contrast, by pre‐mixing the MLG (3 phr) with CIIR using an ultrasonically assisted solution mixing procedure followed by two‐roll milling, the properties (rheological, curing, and mechanical) were improved substantially compared with the MLG/CIIR nanocomposites mixed only on the mill. The Young's moduli of the nanocomposites mixed in solution increased by 38%. The CIIR/MLG nanocomposites produced via solution showed superior durability against weathering exposure. Copyright © 2016 John Wiley & Sons, Ltd.     

The effect of initiators and oxidants on the morphology of poly [(±)‐2‐(sec‐butyl) aniline] a chiral bulky substituted polyaniline derivative

The nano and micro sphere synthesis of chiral bulky substituted polyaniline from monomer (±)‐2‐sec‐butylaniline in bulk and template‐free method (rapid mixing) was done successfully using ammonium peroxydisulfate (APS) and FeCl₃·6H₂O as oxidants. The effect of initiators such as p‐phenylendiamine and 1,4‐benzenediamine, temperature and concentration of monomer on morphology is demonstrated by scanning electron microscopy (SEM) images. The nano and micro sphere morphology was obtained using initiators. Smallest particles were achieved when 1,4‐benzenediamine was used as initiator in the presence of FeCl₃·6H₂O as oxidant. By increasing the concentration of monomer more uniform spheres were obtained. Characterization was made via FT‐IR, UV–Vis, ¹H and ¹³C‐NMR spectroscopy. Elemental analysis and electrical conductivity of products are also presented. All analysis data are in good agreement with nigraniline oxidation state of polyaniline. Copyright © 2015 John Wiley & Sons, Ltd.     

利用激光测量气体微小体积变化装置的开发

开发了一种利用激光精确测量橡胶体积变化的装置.将橡胶浸入到密闭容器内的介质油中,当激光束照射到油面时将被沿原路反射.容器内的气体压力增加而导致液面下降时,即引起光路长度的增加.因此通过测量光路长度的变化可以实现橡胶体积弹性系数的测量.结果表明,橡胶的体积弹性系数与压力无关,表明本次开发的试验装置具有相当良好的精确度,对于诸如气体的扩散量等的精密测量具有现实意义.     

石子河治理工程中橡胶坝的施工措施

以长治市石子河治理工程为例,详细介绍了河道治理工程中有关橡胶坝基础施工及坝袋安装的措施和注意事项。     

地震作用下简支梁桥的碰撞反应分析

为了研究地震作用下简支梁桥的碰撞响应,本文通过建立全桥模型,在输入不同的地震激励、考虑不同桥墩高度下,进行了简支梁桥地震响应时程分析。结果表明:地震作用下碰撞在一定程度上显著地改变了桥梁结构的响应状态,增大了墩底的弯矩和剪力;桥墩的高度和地震激励的变化会对梁间碰撞产生影响。     

带橡胶缓冲垫的出弹装置碰撞有限元分析

齿轮齿条式出弹装置刚性顶杆与炮弹之间存在瞬时碰撞问题.为减小碰撞力,在顶杆端部增加橡胶缓冲垫.采用Mooney-Rivlin模型建立了橡胶缓冲垫的本构模型,并用有限元ANSYS/Workbench软件对带橡胶缓冲垫的出弹装置和炮弹的接触碰撞特性进行数值模拟研究.分析结果表明:带橡胶缓冲垫的顶杆与炮弹的碰撞过程中,炮弹所受的最大应力为1.2387 MPa,远小于炮弹外壳材料的屈服强度;齿轮和齿条的齿面接触应力安全系数分别为3.77和3.81;齿根接触应力安全系数分别为4.03和3.53,均达到较高可靠度时最小安全系数的要求.     

港口集装箱码头轮胎式龙门吊优化调度研究

随着贸易全球化的到来,集装箱运输业飞速发展,港口集装箱码头受到越来越多的重视。轮胎式龙门吊体积大,作业效率低,该环节 已经成为码头作业的瓶颈。提出了轮胎式龙门吊优化调度混合整数规划模型,研究了定量作业条件下的龙门吊优化调度问题,通过实际案例分 析为码头管理者提供决策支持。     

Adapting the Accelerated Solvent Extraction Method for Resin and Rubber Determination in Guayule Using the BÜCHI Speed Extractor

Guayule (Parthenium argentatum Gray) is a promising alternative source to Hevea brasiliensis for the production of natural rubber, which can reach levels of 8–9% under industrialized farming conditions. The most common method for determining rubber concentration is by accelerated solvent extraction (ASE), a technique developed by the Dionex Corporation and almost exclusively performed with the Dionex ASE-200 or 350 systems. Herein, it is sought to apply and adapt the most common methods used in the literature for the Dionex system to another extraction platform, the BÜCHI Speed Extractor E-914. Results showed that using a sand sandwich method to confine the sample in the center and exploiting a larger cell volume (80 mL) for extraction prevents the occurrence of overpressure and problems with clogging. Under optimized conditions, the coefficient of variation was <15% for both resin quantification for samples containing 5.0–15.8% of resin and for rubber quantification for samples with 1.7–10.3% rubber content. The extraction time for resin (2 cycles of 5 min each) was smaller than for rubber (2 cycles of 20 min each). It would be interesting to carry out interlaboratory comparisons to standardize the method at an international level.     

Potential use of NR and wood/NR composites as thermal neutron shielding materials

This work investigated thermal neutron shielding, cure characteristics and mechanical properties of natural rubber (NR) and wood/NR composites with addition of either boron oxide (B₂O₃) or boric acid (H₃BO₃) for potential use as flexible shielding materials. The results showed that increase in the B₂O₃ or H₃BO₃ content from 0 to 80 phr and 0–50 phr in 10-phr increments, respectively, could improve thermal neutron shielding properties but reduced overall tensile properties, while the addition of 20-phr wood particles in wood/NR composites improved surface hardness and dimensional stability. Furthermore, the values of the Half Value Layer (HVL), which represent the required thickness of material to attenuate half of the incoming neutrons, were evaluated at a content of 80-phr B₂O₃ by varying thickness of both NR and wood/NR composites from 2.5 mm to 20.0 mm in 2.5-mm increments. The results indicated that the HVL values were approximately the same at 3.5 mm. Hence, the overall properties investigated in this work suggested great potential of these composites to be used as effective thermal neutron shielding materials.     

On the wall slip phenomenon of elastomers in oscillatory shear measurements using parallel-plate rotational rheometry: I. Detecting wall slip

A systematic study is presented in order to reveal the occurrence of wall slip of pre-prepared elastomeric samples characterized with the use of rotational rheometry. To exclude effects that could be attributed to additional functional fillers, both an unfilled (primarily used) and lightly silica reinforced (complementary system) silicone rubber are evaluated. Cylindrical samples are prepared by casting using a standardized methodology and examined by means of a stress-controlled parallel-plate rotational rheometer. As a control test, samples are also cured within the rheometer (in situ), thereby fixing them to the measuring plates and firmly establishing their response in “no-slip” conditions. The experiments suggest that wall slip, postulated to be caused by an adhesive failure at the sample-plate interface, may occur if the deformation is sufficiently large and no cohesive failure is present. It is detected by an increase in the loss modulus that is related to the adhesive failure associated with local dynamic friction, resulting in increased dissipated energy. Direct (via raw waveform data and normalized Lissajous figures) and indirect (via fast-Fourier-transformation) analysis of the overall system response for a single steady state deformation cycle provided further insights into the mechanism of wall slip.