无机纳米复合技术在热塑性弹性体研究中的应用

综述了热塑性弹性性/无机物纳米复合的研究进展,并展望其技术发展趋势。     

增塑剂对丁腈橡胶/聚丙烯热塑性硫化橡胶性能的影响

研究了邻苯二甲酸二辛酯(DOP)、偏苯三酸三(2-乙基己酯)(TOTM)、聚酯和邻苯二甲酸烷基.苄酯4种增塑剂对丁腈橡胶(NBR)聚/丙烯(PP)热塑性硫化胶(TPV)邵尔A硬度、耐油性能和流变性能的影响,并用透射电镜分析了4种增塑剂对NBR/PP TPV相态结构的影响。结果表明,TOTM的增塑效果最好,可制备出低硬度、高耐油和流动性好的NBR/PP TPV,并且分散相的粒径小、大小均匀;随着TOTM用量的增加,NBR/PP TPV的邵尔A硬度降低,流动性提高,但TOTM用量不宜超过50份。     

负载钛体系催化1-丁烯与1 - 己烯共聚合

以负载钛体系(简称Ti)为主催化剂,三异丁基铝(简称Al)为助催化剂,加氢汽油为溶剂,通过1-丁烯(Bt)与1-己烯(He)共聚合成了新型无规热塑性弹性体。研究了单体摩尔比、Ti/(He Bt)(摩尔比)、Al/Ti(摩尔比)、反应温度、反应时间对转化率、催化剂效率(CE)、聚合物的特性黏数([η])及其在CH2Cl2中不溶物含量的影响,并用傅里叶变换红外光谱、核磁共振对共聚物进行了表征。结果表明,Bt与He最佳共聚合条件为He/Bt0·25,Al/Ti400~500,Ti/(He Bt)3×10-5~4×10-5,反应温度40~50℃,反应时间4h。随着共聚单体中He初始含量、Ti/(He Bt)的增加,共聚物的[η]增大;随着Al/Ti的增加、反应温度的升高,共聚物的[η]减小;随着Al/Ti的增加及反应温度的升高,共聚物在CH2Cl2中的不溶物含量下降;随着Ti/(He Bt)的增加和反应时间的延长,共聚物在CH2Cl2中的不溶物含量增大;He的加入降低了聚1-丁烯(1-PBt)的立构规整性和1-PBt的结晶度。     

负载钛催化1-丁烯聚合动力学

采用TiC l4/MgC l2-A l(i-Bu)3催化剂合成聚1-丁烯热塑性弹性体,研究了不同单体浓度、催化剂浓度和反应温度下及催化剂陈化后的聚合动力学。结果表明,聚合初期聚合速率与单体浓度和催化剂浓度的一次方成正比,在20~40℃,聚合的表观活化能为14 kJ/mol,聚合的速率方程为Rp=kp[Ti][B t];0℃陈化催化剂的1-丁烯聚合速率较非陈化时快。     

热塑性聚氨酯弹性体与乙华平橡胶共混物的性能

将聚酯型和聚醚型聚氨酯弹性体(TPU385E,TPU8685)分别与不同乙酸乙烯酯含量的乙华平橡胶(EVM400,EVM700)进行共混,考察了原料种类、共混比对共混物力学性能和耐磨性的影响。结果表明,随着TPU用量的增加,EVM/TPU共混物的拉伸强度、邵尔A硬度、100%定伸应力和300%定伸应力均提高,扯断伸长率下降;随着EVM用量的增加,EVM/TPU共混物的拉伸强度、邵尔A硬度、100%定伸应力和300%定伸应力均降低,扯断伸长率增大;随着TPU用量的增加,EVM/TPU共混物的耐磨性提高;TPU8685/EVM400共混物具有最大的拉伸强度,TPU385E/EVM700共混物具有最大的扯断伸长率,TPU8685/EVM700共混物具有最好的耐磨性;当2种TPU与EVM400质量比都为50/50时,TPU385E/EVM400的耐磨性最差。     

聚氨酯弹性体/无机纳米粒子复合材料研究进展

纯聚氨酯弹性体（PUE）的耐极性溶剂和耐热性较差,限制了其在某些领域的应用,用纳米无机粒子对其进行改性是提高其性能的一种有效措施。介绍了机械混合法、原位聚合法、插层聚合法几种常用的聚氨酯纳米改性方法及其研究进展。     

基于有限元分析的大量程力传感器设计改进

采用有限元法对现有的80t大量程力传感器进行分析,并根据电桥原理获得满量程的输出电压值,从而指出其精度较低的原因,并重新确定了贴片方式;通过试验对改进的结果进行了验证,结果表明,通过有限元法对传感器贴片方式的改进取得了明显的效果。     

Electro-thermal and -mechanical model of thermal breakdown in multilayered dielectric elastomers

Multiple breakdown phenomena may take place when operating dielectric elastomers. Thermal breakdown, which occurs due to Joule heating, becomes of special importance when using multilayered stacks of dielectric elastomers, due to the large volume-to-surface-area-ratio. In this article, a 2D axisymmetric finite-element model of a multilayered stack of dielectric elastomers is set up in COMSOL Multiphysics®. Both the electro-thermal and electro-mechanical couplings are considered, allowing for determination of the onset of thermal breakdown. Simulation results show that an entrapped particle in the dielectric elastomer drastically reduces the possible number of layers in the stack. Furthermore, the possible number of layers is greatly affected by the ambient temperature and the applied voltage. The performance of three hyperelastic material models for modeling the elastomer deformation are compared, and it is established that the Gent model yields the most restrictive prediction of breakdown point, while the Ogden model yields the least restrictive estimation.     

Effect of temperature on the performance of laterally constrained dielectric elastomer actuators with failure modes

This article analytically investigates the temperature influence on the performance of laterally constrained dielectric elastomer actuators. The effects of both temperature and stretches on the permittivity are taken into consideration. The governing equations of state are established by modeling the actuator as a thermodynamic system of three degrees of freedom. Various failure modes, including electromechanical instability, electric breakdown, loss of tension, and tensile rupture are considered to restrict the operation state and to determine the region of allowable state. Numerical calculations are performed to depict the variations of some important physical quantities with generalized coordinates and to gain insight on the influence of temperature on the critical curves of failures. It is shown that the temperature has obvious effects on the operation state and the allowable region. The present results can be used for designing and optimizing an actuator, and the present approach can be extended to other kinds of dielectric elastomer actuators with complex geometries.     

竹原纤维增强低熔点聚酯复合材料的制作及其性能研究

采用非织造加工工艺将经适当脱胶处理的竹原纤维与低熔点聚酯(LMPET)纤维制成混合纤维预成型件,经模压成型制成竹原纤维增强LMPET复合材料板材。研究表明,当模压温度、时间及压力分别为170℃、20 m in及30 MPa,竹原纤维的质量分数为40%时,制得的复合材料的纵、横向拉伸强度分别为136.0、87.6 MPa;纵、横向弯曲强度分别为534.0、470.0 MPa。竹原纤维增强LMPET复合材料初步确定可用于汽车、建材等领域。