介孔材料SBA-15为修复剂载体的环氧树脂自修复形状记忆复合材料

将介孔二氧化硅SBA-15(MS)装载甲基丙烯酸缩水甘油酯(GMA)修复体系(MS@GMA),引入氢化双酚A环氧树脂与聚醚胺组成的形状记忆环氧基体(SMEP)中,得到MS@GMA/环氧自修复形状记忆复合材料(SMPC)。研究了介孔材料含量与表面改性对SMPC的力学性能、自修复以及形状记忆性能的影响。扫描电子显微镜结果表明,当MS用量在4%以下时,其在SMPC中分散良好,划痕损伤能够在裂纹处通过释放的GMA聚合而修复。对SMPC进行动态力性能分析与U型折叠-展开形状记忆,测试结果表明,复合材料储能模量最高提升32%,保留形状记忆特征,复合材料在经受8次循环测试后能够较好地保持形状回复率。采用单边切开梁法测试复合材料的断裂韧性修复性能,在添加4%硅烷偶联剂改性的MS@GMA时自修复效率最高,可达68%。     

纤维增强形状记忆聚合物复合材料的热变形行为

通过将热力学内变量理论与Adam-Gibbs结构松弛模型相结合的方法,构建了适用于描述非晶态形状记忆聚合物(SMP)玻璃化转变过程中热变形行为的模型。在此基础上,利用复合材料细观力学分析方法进一步建立了纤维增强形状记忆聚合物复合材料(SMPC)热膨胀系数模型。模型中考虑了温度变化对基体弹性模量和泊松比在玻璃化转变过程中的影响。研究了一种含T300碳纤维增强相SMPC的热变形行为,结果表明,SMPC的各向热应变在升降温阶段几乎一致,仅在玻璃化转变附近微小分离;较快降温率导致的低温态热应变略小,而较快升温率导致平衡态温度更高; x向热应变随纤维倾角增大而增大,随纤维含量增大而减小。研究结果可对纤维增强SMPC的设计与应用提供一定理论参考。     

纤维增强形状记忆聚合物复合材料及其航天应用

形状记忆聚合物(SMP)是一种能够保持临时形状,并在外界刺激下自发回复到其初始形状的智能材料,具有高形状固定率、高形状回复率、转变温度可调、变形能力强、质量轻等优点,但其应用受到响应方式单一和承载能力差的限制,通过向聚合物中添加功能颗粒或增强纤维制成形状记忆聚合物复合材料(SMPC),可有效解决这一问题。首先介绍了SMP形状记忆效应的原理,然后阐述了纤维增强型SMPC有限变形过程中纤维的微屈曲行为。最后对可变形结构在航天领域的应用进行了论述。      

GO/TLCP/PF混杂复合材料的热性能和动态力学性能

采用熔融挤出法将热致性液晶聚合物(TLCP)与酚醛树脂(PF)熔融挤出,分别加入氧化石墨烯(GO)、KH550改性GO(KH550-GO)、KH560改性GO(KH560-GO),制备出GO/TLCP/PF混杂复合材料,研究GO的加入对GO/TLCP/PF混杂复合材料的热性能、力学性能、动态力学性能、蠕变和应力松弛的影响。结果表明:GO的加入可提高GO/TLCP/PF混杂复合材料的热性能、力学性能以及动态力学性能;仅加入1%KH560改性的GO,GO/TLCP/PF混杂复合材料的冲击强度比PF复合材料提高了25.6%,储能模量提高了28.1%,蠕变和应力松弛性能也得到改善。其原因是,GO与TLCP具有一定的协同增强效应。     

原位混杂增强热塑性复合材料

提出原位混杂复合材料的结构模型,以聚醚醚酮(PEEK)及聚碳酸酯(PC)为基体进行原位混杂复合.对所得的热致液晶聚合物(TLCP)微纤与宏观纤维混杂增强的TLCP/碳纤维(CF)/PEEK和TLCP/玻璃纤维(GF)/PC原位混杂复合材料的加工流变学、几何学与力学特性进行了研究.     

基于形状记忆复合材料的空间可展桁架结构研究

形状记忆复合材料具有形变恢复力大、恢复率高、恢复稳定性与可靠性好等优点,可广泛应用于空间可展开结构.本文对形状记忆复合材料及其在空间可展桁架结构中的应用进行了初步研究.利用碳纤维增强形状记忆环氧树脂得到的热致型形状记忆复合材料玻璃化转变温度Tg为94℃,可实现"记忆起始态→固定变形态→恢复起始态"循环过程10次以上.基于所研制的形状记忆复合材料,设计了空间桁架、收拢与展开过程及形状记忆铰接头,并提出了悬挂式桁架展开系统设计方案.     

热致液晶高分子与聚酰胺原位复合的研究进展

综述了近年热致液晶聚合物(TLCP)与聚酰胺(PA)的原位复合材料的最新进展,对原位复合材料的形态、力学性能、增容研究以及熔体的流变行为做了系统的阐述.此外,介绍了原位混杂增强复合材料,并简单讨论了TICP/PA的增强机理.     

热致性液晶/氧化石墨烯/酚醛树脂复合材料的力学性能与摩擦性能研究

将酰氯化后的氧化石墨烯与热致性液晶聚合物经溶液混合法制备热致性液晶聚合物/氧化石墨烯(TLCP/GO)混杂材料;通过辊炼、挤出、模压成型工艺制备热致性液晶聚合物/氧化石墨烯/酚醛树脂(TLCP/GO/PF)复合材料,研究TLCP/GO混杂材料含量对酚醛树脂复合材料的力学、动态力学及摩擦性能的影响。结果表明:添加量为0.5%时复合材料的弯曲强度及弯曲模量分别提高了26%及11%;添加量为0.5%时,复合材料初始储能模量提高了31.5%,同时,混杂材料的加入一定程度上改善了复合材料的摩擦磨损性能,其中混杂材料添加量为0.5%时,复合材料的摩擦系数在0.39~0.28之间,250℃时,复合材料的磨损率为0.39×10-7cm3/N·m,比纯酚醛复合材料降低48.7%,表明TLCP与GO具有协同增强作用。     

VGCF/SMPU复合材料的形状记忆性能研究

形状记忆聚氨酯因具有热致形状记忆特性而引起世界的极大兴趣,自20世纪80年代以来迅速发展成为一种新型的功能材料.本文以1-甲基-2-吡咯烷酮(NMP)为溶剂,采用溶液混合法制备了形状记忆聚氨酯/气相生长碳纤维复合材料薄膜,利用扫描电镜观察了气相生长碳纤维在形状记忆聚氨酯中的分散性,测试分析了加入气相生长碳纤维对形状记忆聚氨酯的热致形状记忆性能的影响.扫描电镜观察显示:气相生长碳纤维含量达到3%(质量分数,下同)时在形状记忆聚氨酯中开始有少量团聚现象,含量达到5%后团聚现象比较明显;形状记忆性能测试发现:加入气相生长碳纤维不同程度的降低了复合材料的热致形状记忆性能,根据对形状记忆聚氨酯中两相结构的相分离程度及软段结晶情况的不同影响而反映为对形状记忆性能的不同影响.     

形状记忆聚合物复合材料的研究进展EI北大核心CSCD

形状记忆聚合物复合材料已成为形状记忆材料的研究热点和重点,文中针对近年来形状记忆聚合物复合材料的最新研究进行了综述。分别对颗粒增强、纤维增强和颗粒纤维混合3类增强材料制备的形状记忆聚合物复合材料的结构与性能特点进行了分析和评述;着重阐述了形状记忆聚合物复合材料形状记忆效应的机理以及影响形状记忆行为的因素;分析了形状记忆聚合物复合材料研究中存在的问题,同时对形状记忆聚合物复合材料的应用前景进行了展望。     

Post buckling analysis of the shape memory polymer composite laminate bonded with alloy film

As a new kind of smart materials, shape memory polymer composites (SMPCs) are being used in large in-space deployable structures. However, the recovery force of pure SMPC laminate is very weak. In order to increase the recovery force of a SMPC laminate, an alloy film was bonded on the surface of the laminate. This paper describes the post bulking behavior of the alloy film reinforced SMPC laminate. The energy term associate with this in-plane post buckling have been given .Based on the theorems of minimum energy, a mathematical model is derived to describe the relation between the strain energy and the material and geometry parameters of the alloy film reinforced SMPC laminate. The finite element model (FEM) is also conducted to demonstrate the validity of the theoretical method. The relation between the recovery force and the material geometry parameters were also investigated. The presented analysis shows great potential in the engineering application such as deployment of space structures.     

形状记忆合金混杂复合材料层板的有限元分析与强度研究

形状记忆合金(SMA)与复合材料层板结合后,构成可驱动材料。形状记忆合金的非线性及其与复合材料层板的结合界面的力学性能对整体材料的性能影响较大。通过对埋入形状记忆合金驱动器的复合材料层板进行有限元模拟分析与试验研究,用有限元模拟分析的方法可以比较准确地模拟埋入形状记忆合金后复合材料的应力分布情况,结果表明,形状记忆合金的埋入不会对材料的强度产生较大影响。     

Shape memory properties of multi-walled carbon nanotube/polyurethane composites prepared by in situ polymerization

A high strength multi-walled carbon nanotube (MWCNT)/shape memory polyurethane composite (SMPC) was prepared by in situ polymerization. The effect of MWCNT content and its dispersion on the microstructure, mechanical, and shape memory property of the SMPC were studied by scanning electron microscopy, universal testing machine, and dynamic mechanical analysis. The results showed that MWCNTs can be well dispersed in the composites and the composites with homogeneous dispersion of MWCNTs exhibited superior mechanical properties for MWCNTs supplied cross-link netpoints in the composites. And the materials with 97 % of recovery ratios (R_r) and 94 % of fixing ratios (R_f) indicated that this SMPC is a prominent potential candidate for smart actuator.     

A finite element model of shape memory polymer composite beams for space applications

Structures made of shape memory polymer composite (SMPC), due to their ability to be formed into a desired compact loading shape and then transformed back to their original aperture by means of an applied stimulus, are an ideal solution to deployment problems of large and lightweight space structures. In the literature, there is a wide array of work on constitutive laws and qualitative analyses of SMP materials; dynamic equations and numerical solution methods for SMPC structures have rarely been addressed. In this work, a macroscopic model for the shape fixation and shape recovery processes of SMPC structures and a finite element formulation for relevant numerical solutions are developed. To demonstrate basic concepts, a cantilever SMPC beam is used in the presentation. In the development, a quasi‐static beam model that combines geometric nonlinearity in beam deflection with a temperature‐dependent constitutive law of SMP material is obtained, which is followed by derivation of the dynamic equations of the SMPC beam. Furthermore, several finite element models are devised for numerical solutions, which include both beam and shell elements. Finally, in numerical simulation, the quasi‐static SMPC beam model is used to show the physical behaviors of the SMPC beam in shape fixation and shape recovery. Copyright © 2015 John Wiley & Sons, Ltd.     

碳纳米管和TiB2混杂增强铜复合材料的电弧侵蚀行为

采用放电等离子烧结（SPS）工艺制备出不同混杂比例碳纳米管（CNTs）和TiB₂混杂增强铜（CNTs-TiB₂/Cu）复合材料,对复合材料致密度、硬度、导电率、导热率和显微组织进行了对比和分析。同时对复合材料进行了电接触试验,研究了不同电流条件下CNTs与TiB₂混杂比例对CNTs-TiB₂/Cu复合材料电弧侵蚀行为的影响。结果表明:随着CNTs与TiB₂混杂比例的增加,CNTs-TiB₂/Cu复合材料的密度、硬度、导电率和导热率逐渐降低,铜基体晶界分离现象越来越明显;在特定电流条件下,合适的CNTs-TiB₂混杂比例可提高CNTs-TiB₂/Cu复合材料的抗电弧侵蚀性能;当电流为5 A和10 A时,CNTs与TiB₂混杂比例为4∶1的平均燃弧能量、平均燃弧时间和材料转移量达到最低,而电流为15 A时,CNTs与TiB₂混杂比例为1∶4的平均燃弧能量、平均燃弧时间和材料转移量达到最低。电弧侵蚀后阴极出现熔池、气孔及熔融金属铺展等特征,且随着CNTs与TiB₂混杂比的增加,CNTs-TiB₂/Cu复合材料熔池面积减小,气孔数量变少,熔融金属铺展的特征减弱。      

A study on a possible correlation between thermal conductivity and wear resistance of particulate filled polymer composites

In this study, thermal conductivity of particulate filled polymer composites is investigated experimentally by guarded heat flow meter method in accordance with ASTM E 1530. The objective of this research is to attain a better understanding of global and local thermal behavior of a composite system through basics of thermal properties. The results obtained from this study are compared with an existing theoretical model for validation purposes of pine bark reinforced epoxy based resin composites with and with out particulate filler content. To this end, a correlation has been made between the thermal conductivity and specific wear resistance of the tested samples, highlighting the importance of the insulating material. The relationship between control factors and performance outputs are established by means of non-linear regression analysis resulting in a valid mathematical model. Finally, a popular evolutionary approach known as genetic algorithm (GA) is used to generalize the method of finding out optimal factor settings for minimization of thermal conductivity and specific wear rate.     

Properties and mechanism of two-way shape memory polyurethane composites

Recently, smart materials have drawn wide attention from many researchers. In this paper, laminated shape memory polymer composite (SMPC) exhibiting two-way shape memory effect (SME) has been prepared by combining the pre-elongated shape memory polyurethane (SMPU) with the un-elongated elastic polyurethane (PU). Then the shape memory behaviors, laminated structure and two-way SME mechanism are investigated systematically. The results show that two-way shape memory behaviors, i.e., bending upon heating and reverse bending upon cooling, are achieved in the resulted SMPU-based-SMPCs. In addition, the SMPCs show the compositive thermal properties and dynamic mechanical properties due to their physical combination of layer-by-layer. Furthermore, the shape memory mechanism can be ascribed to the reversible change of two forces, i.e., recovery force in the SMPU layer and bending force in the elastic PU layer.     

多功能聚吡咯/聚酰亚胺电磁屏蔽复合膜的制备与性能研究

目的 开发具有优异屏蔽效率、轻质且热稳定性良好的电磁屏蔽材料。方法 以聚酰亚胺(PI)为聚合物基体,聚吡咯(PPy)为添加相,采用静电纺丝-低温原位聚合技术制备PPy/PI电磁屏蔽复合膜。通过在薄膜内部的多孔结构中构建致密的导电网络,赋予复合膜优异的导电性和高效的电磁屏蔽效能。结果 在聚合PPy浓度为0.1 mol/L时,复合膜的电导率和电磁屏蔽效能分别为2.23 S/cm和26.04 dB,且其单位厚度电磁屏蔽效能可达到110.81 dB/mm,展现出优异的电磁屏蔽性能。结论 PPy/PI复合纤维膜表现出良好的力学性能(拉伸强度为11.73 MPa)、优异的热稳定性(>400 ℃)和力学传感性能,具备在恶劣环境下广泛应用的潜力。     

Ballistic-performance optimization of a hybrid carbon-nanotube/E-glass reinforced poly-vinyl-ester-epoxy-matrix composite armor

The material model for a multi-walled carbon nanotube (MWCNT) reinforced poly-vinyl-ester-epoxy matrix composite material (carbon nanotube reinforced composite mats, in the following) developed in our recent work (M. Grujicic et al. submitted), has been used in the present work within a transient non-linear dynamics analysis to carry out design optimization of a hybrid polymer-matrix composite armor for the ballistic performance with respect to the impact by a fragment simulating projectile (FSP). The armor is constructed from E-glass continuous-fiber poly-vinyl-ester-epoxy matrix composite laminas interlaced with the carbon nanotube reinforced composite mats. Different designs of the hybrid armor are obtained by varying the location and the thickness of the carbon nanotube reinforced composite mats. The results obtained indicate that at a fixed thickness of the armor, both the position and the thickness of the carbon nanotube reinforced composite mats affect the ballistic performance of the armor. Specifically, it is found that the best performance of the armor is obtained when thicker carbon nanotube reinforced composite mats are placed near the front armor face, the face which is struck by the projectile. The results obtained are rationalized using an analysis of the elastic wave reflection and transmission behavior at the lamina/met and laminate/air interfaces.