Analysis and Verification on the Chain-like Model with Normal Distribution of Magnetorheological Elastomer

在磁流变弹性体链化模型的基础上,引入斜链夹角的正态分布,采用偶极子法从理论上分析了诸多因素对磁流变弹性体磁致剪切模量的影响,包括颗粒链的初始倾斜角、外加磁场强度、剪应变大小等,并进行了实验验证.     

Radiation Vulcanization of Magnetorheological Elastomers Based on Silicone Rubber

介绍了两种制备磁流变弹性体的硫化方法即高温硫化和辐射硫化. 研究中采用动态力学分析仪(DMA)测量了样品的动态力学特性.特别是对样品的磁流变效应和耐久性进行了详细的测试. 实验结果表明,经过辐射硫化的样品具有更大的零场模量和磁致模量,以及更好的磁流变效应和耐久性. 为了解释这些结果,文章对样品的体积形变和增塑剂渗出都作了详细的分析. 在硫化过程中样品的体积保持稳定是辐射硫化样品具有大磁致模量的重要原因,而增塑剂渗透性小也是辐射硫化样品具有高磁流变效应和耐久性的重要因素.     

Liquid crystalline cellulose derivative elastomer films under uniaxial strain

Mesogenic cellulose derivative chains cross-linked into free-standing thin films were prepared by a shear-casting technique from anisotropic precursor solutions of thermotropic (acetoxypropyl)cellulose. After shear cessation a macroscopically oriented serpentine structure with the director in average along the shear direction is locked resulting in anisotropic optical and mechanical properties of the material. These films were submitted to an external uniaxial mechanical field perpendicular and parallel to the shear direction. Stretching perpendicular to the shear direction produced significant director rotations and a reset of order of the director order parameter for a deformation in the range 2–3 as detected by X-rays and optical microscopy. The different response found for strains imposed parallel and perpendicular to the initial average director orientation indicates that even though our system shows a serpentine director modulation that is either attenuated or reinforced by deformations parallel or perpendicular to the shear direction, its behaviour is similar to theoretical predictions for monodomain nematic elastomers described in the literature.     

F-C烷基化反应原位增容PS/POE共混物中降解的抑制和增容效果的优化

在聚苯乙烯(PS)/聚烯烃弹性体(POE)/AlCl3共混物中引入苯乙烯(St)单体,增加了共混体系中的不饱和结构,AlCl3催化剂与St反应生成大量的初始碳正离子,这些初始碳正离子进攻POE链生成更多的大碳正离子,进而形成更多的PS-graft-POE共聚物,提高了接枝效率.进而,采用"两次挤出"技术,即先原位增容制成接枝母料,然后接枝母料再与PS和POE二次挤出,可以在一定程度上缓解组份的降解,使共混物的力学性能得到进一步的改善.     

原子力显微镜在聚烯烃研究中的应用

聚烯烃材料因其卓越的性能和较低的价格广泛应用于工农业、医疗卫生、军事、日常生活等领域。为了拓展聚烯烃材料的应用范围,表面功能化聚烯烃、聚烯烃与其他材料的共混物以及聚烯烃/无机纳米复合材料等得到了发展,并成为该领域的研究热点。原子力显微镜(AFM)是利用一个极为尖锐的针尖与样品间的相互作用力进行材料表面的形貌、物理和化学信息探测的一种技术,它在上述聚烯烃研究中发挥着重要作用。表面粗糙度是聚烯烃材料表面功能化研究中的重要参数之一,AFM技术则能够给出准确的表面粗糙度信息。由于AFM技术能够直观地观察各组分的混合状态及相分离情况,因此AFM技术成为聚烯烃与其他材料共混研究的重要手段之一。此外,AFM是一种非常有效的微纳米结构形貌的表征方法,在聚烯烃的结晶研究方面也得到了应用。本文简单介绍了AFM表面形貌观测的工作原理和工作模式,主要阐述AFM在聚烯烃材料研究中的三个主要应用:材料表面粗糙度、共混相分离以及结晶研究。     

Inflation analyses of a circular elastomeric membrane with hydrostatic pressure

Composite diaphragm inflation (CDI) experiment is a useful methodology for exploring the mechanics relation of cell-cell junctions within a living epithelial sheet. In this paper, a new methodology of CDI experiment has been put forward. The finite deformation of a circular polydimezhylsiloxane elastomeric membrane, which is used as the substrate for the culture of epithelial cells, under hydrostatic pressure is explored by the theory of non-linear continuum mechanics. The simplified governing equations with minimum amount of differential equations and boundary conditions are obtained and solved by multiple shooting method. The influences on the membrane by hydrostatic pressure have been discussed.     

叶立德活性聚合制备基于聚亚甲基的大分子单体

利用叶立德活性聚合方法制备了两种基于聚亚甲基的大分子单体. 其中一种是以叶立德活性聚合制备的主链链端含有羟基的聚亚甲基(PM-OH)为原料, 通过链端羟基的基团转换, 得到链端含有甲基丙烯酸酯基的大分子单体. 另一种则是以硼烷-四氢呋喃(BH₃-THF)和二乙烯基苯反应得到的三烷基硼中间体为催化剂和引发剂, 然后进行叶立德活性聚合, 再经过二水合氧化三甲胺(TAO)的氧化, 最终得到基于聚亚甲基的一端含有羟基另一端含有苯乙烯基的大分子单体. 通过高温核磁氢谱、傅立叶红外光谱和高温凝胶色谱法表征了这两种大分子单体的链结构和分子量及其分布.     

Contraction of side-on nematic liquid crystalline elastomers micropillars: Influence of molecular parameters

We investigated the structure-property relationship of nematic liquid crystalline elastomer (LCE) actuators obtained from a series of nematic side-on monomers. The liquid crystalline acrylate monomers were designed and synthesized with different tail lengths. Combining a soft lithography technique with photo-polymerization/photo-crosslinking of aligned nematic liquid crystalline monomers and crosslinkers, nematic LCE micropillars were obtained, based on the new monomers. Through microscopic observation, influence of some structural parameters on the thermo-mechanical behavior of the micropillars was investigated. The thermo-mechanical behavior of the LCEs showed a close correlation with to the tail length of the monomer and the spacer length of the crosslinker.     

Polyolefin,olefin copolymers and polyolefin polyblend nanocomposites

This paper reviews recent studies done in academia or industrial laboratories on polymer nanocomposites based on various type of polyolefins like homopolymers, copolymers and polyblends reinforced with various mineral (montmorillonite, bentonite, closite, laponite, layered double hydroxide, etc.) carbon based (graphite, carbon nanotubes, carbon nanofibers, exfoliated graphite, graphene, carbon black, etc.) nanofillers. The review covers their preparation, their mechanical, thermal, flammability, gas barrier capability, electrical, dielectrical, antibacterial characteristics and their potential applications like low weight structural materials, part of optical devices, thermal interface materials, electric and electromagnetic components, absorption, antibacterial materials, etc.     

Tunable guided-mode resonance filter based on dielectric elastomer actuators

A tunable guided-mode resonant (GMR) reflection filter based on dielectric elastomer actuators (DEA) is designed. Simulating the characteristics of the filter with rigorous coupled wave analysis, it is shown that the resonant wavelength of the kind of GMR filter can be tuned from 1442.8 nm to 1644.6 nm by applying voltage on the dielectric elastomer actuators which changes the period of the grating layer of the GMR filter conveniently. Furthermore, there is an almost perfect linear relationship of resonant wavelength tuned and the period varied with negligible effect on the linewidth.