微胶囊自修复聚合物材料的发展

对微胶囊自修复聚合物材料近年来一些新的研究进展进行了综述,包括微胶囊自修复聚合物材料技术的发展历程,荧光数字图像技术、光测弹性技术在微胶囊自修复聚合物材料研究领域的应用以及微胶囊／微血管自修复聚合物材料制备的技术要点。     

环氧树脂微胶囊与潜伏性固化剂自修复体系断裂韧性的研究

微胶囊二元自修复系统对聚合物基复合材料在使用中产生的微小裂纹具有修复作用,但微胶囊和固化剂的加入会对基体材料的断裂韧性产生影响。本文研究了环氧树脂微胶囊和咪唑类潜伏性固化剂对聚合物基复合材料基体材料的断裂韧性的影响。采用环氧树脂E-51作为基体材料,三乙烯四胺为常温固化剂,咪唑类衍生物2MZ-Azine和实验室自制的包含环氧树脂芯材的微胶囊为材料制作断裂韧性拉伸试样。实验结果表明,当微胶囊的含量达到一定比例之前,基体材料的断裂韧性随着微胶囊含量的增加而增强,当微胶囊含量超过此比例后,基体材料的断裂韧性随着微胶囊含量的增加而减小,潜伏性固化剂的加入会增大基体材料的断裂韧性。这与环氧树脂材料增韧理论相符合。     

微胶囊型自修复涂料的研究进展

传统聚合物涂料在使用过程中因外界因素不可避免的产生划伤或裂纹,其保护性能就会大大降低,极大的缩短了聚合物涂料的使用寿命,增加了巨大的经济成本。经过国内外学者大量深入的研究,将自修复技术应用于复合涂料领域,即制备自修复聚合物涂料成为智能涂料发展的重要方向之一。本文根据自修复微胶囊外壳材料的不同,描述了几种常见的微胶囊型自修复涂料体系,包括脲醛树脂外壳体系、聚脲外壳体系、聚氨酯外壳体系等。     

微胶囊自修复聚合物材料的研究进展

论述了微胶囊自修复聚合物材料的自修复机理,阐述了微胶囊制备技术,特别是以脲醛树脂为囊材的原位聚合法制备技术,分析了自修复聚合物材料对微胶囊结构和性能的要求,概述了微胶囊自修复聚合物材料的研究成果,指出其中的优缺点,提出今后研究的方向和重点内容。     

自修复聚合物材料用微胶囊的研究进展

介绍了微胶囊自修复聚合物材料的自修复机理,阐述了微胶囊的制备技术。讨论了近年来在该领域最新的研究成果,展望了微胶囊自修复复合材料的研究方向。     

环氧树脂微胶囊的制备与性能研究

随着社会快速发展,人们对材料的安全性和耐久性越来越重视。复合材料在使用过程中,受到外界荷载、温度等环境作用,材料内部会产生微裂纹。将自修复材料微胶囊化,可修复材料微裂纹,改善材料耐久性,并提高复合材料使用寿命。本研究采用原位聚合法制备微胶囊,以尿素与甲醛作为壁材,环氧树脂E51为芯材制备,具有致密性较好,反应速率较快,且聚合物相对分子质量高等优点。在此基础上,本文系统地研究了合成工艺对环氧树脂微胶囊性能的影响。分析研究了微胶囊的形貌、化学结构、平均粒径,以及这些差异对微胶囊性能的影响。确定了影响微胶囊产率、芯材含量、抗渗透性、平均粒径的最大因素为反应时间。结果表明,制备的微胶囊为球形,粘性小,且成功将环氧树脂包覆在微胶囊中。测定最佳条件下微胶囊的产率和芯材含量分别为64.9%和69.6%。     

沥青自愈合技术的研究进展与展望

从自愈合聚合物材料的主要愈合机理和沥青材料自愈合的方法两个角度介绍沥青材料自愈合技术的研究进展。高分子聚合物材料的愈合机理包括:基于微胶囊和液芯纤维的愈合方法;基于可逆共价键和非共价键的愈合机理;基于形状记忆材料以及纳米粒子的自修复机理等。简单介绍了沥青材料发生自愈合的理论基础。沥青材料的自愈合方法包括:微胶囊法;自愈合聚合物材料改性沥青;加热愈合方法。分析了沥青材料自愈合几种不同方法的优缺点,并对未来的研究方向做出了展望:微胶囊法属于聚合物材料愈合中初级的修复方法,属于被动修复且局限性较多。沥青自愈合的研究应着眼于促进或提高沥青自身的自愈合能力和提出新的加热促进愈合的方法。     

自修复聚合物材料用微胶囊的研究进展

自修复材料是一种新型的智能材料。将微胶囊埋植于材料中是实现其自修复的一种方法,也是目前该领域的研究热点之一。本文介绍了微胶囊型自修复的概念和原理,综述了近几年来DCPD型微胶囊、环氧树脂型微胶囊、硅油型微胶囊以及其他微胶囊型自修复的发展状况,并着重介绍了最新研究成果,对微胶囊型自修复材料的研究前景进行了展望。     

微胶囊型自修复聚合物复合材料研究进展

介绍了聚合物复合材料自修复的概念和机理,自修复体系的组成和要求以及自修复材料的评价方法。综述了最近几年对影响复合材料自修复效果的4个方面因素(微胶囊的含量及粒径、修复剂的种类、催化剂的用量和粒子尺寸以及体系混合次序)的研究进展。     

微胶囊自修复技术及其在聚合物基复合材料中的应用

论述了微胶囊自修复技术以及自修复机理,重点阐述了微胶囊自修复技术在聚合物基复合材料中应用的最新研究成果.通过分析聚合物基自修复复合材料对微胶囊结构和性能的要求,指出了今后的发展方向和应用前景.     

Effect of strain hardening of shape memory polymer fibers on healing efficiency of thermosetting polymer composites

Recently, shape memory polymer fibers (SMPFs) have been used in a biomimetic two-step (Close-Then-Heal) self-healing system for healing macroscopic cracks. The objective of this study was to investigate the effect of cold-drawing programming of SMPFs on the healing efficiency of conventional thermosetting polymer composites and the possibility of healing wide-opened crack by localized heating. To achieve the objective, continuous SMPF strand reinforced conventional epoxy composite beam specimens, which were dispersed with thermoplastic particles, were prepared. The SMPF strands were cold-drawn to various pre-strain levels before casting the polymer matrix. Repeated fracture/healing test was conducted by uniaxial tension. It is found that the composites were able to repeatedly heal macroscopic cracks. Strain-hardening by cold-drawing increased the healing efficiency considerably. It was demonstrated that healing can be achieved by heating locally surrounding the cracked region. The mechanism for the enhanced recovery stress was due to cold-drawing induced molecular alignment and formation of some perfect crystals in the hard segment domain of the SMPF.     

Performance of self-healing epoxy with microencapsulated healing agent and shape memory alloy wires

We report the first measurements of a self-healing polymer that combines a microencapsulated liquid healing agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid healing agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the healing period. We show that dramatically improved healing performance is obtained by the activation of embedded SMA wires. We conclude that improved healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the healing agent due to the heat produced by the activated SMA wires.     

Advances in healing-on-demand polymers and polymer composites

Healing-on-demand materials exhibit the capability to close cracks and heal the closed/narrowed cracks when needed and to recover functionality using intrinsic or extrinsic resources. In this paper, advances in healing-on-demand polymers and polymer composites in the past decade are reviewed, covering different schemes and technologies used to trigger crack closure and to heal molecularly. A balanced review on non-load-bearing polymers and polymer composites as well as load-carrying polymers and polymer composites is presented. The progress in self-healing polymers and polymer composites has been well discussed recently in the literatures. In this review, therefore, less attention has been paid on what has been widely reported; we primarily focus on healing-on-demand materials concerned with large volume damage healing by a close-then-heal (CTH) strategy. The healing-on-demand material by the CTH approach undergoes a process of crack closure, followed by crack healing with healing agents. Healing theories, including those within the continuum damage mechanics framework, and healing efficiency evaluations are also reviewed. Perspectives on future development in this emerging research area are discussed.     

Torsion fatigue response of self-healing poly(dimethylsiloxane) elastomers

Incorporating self-healing functionality in a polysiloxane elastomer successfully retards the growth of fatigue cracks under torsional fatigue loading. The fully in situ self-healing material consists of a microencapsulated vinyl-terminated poly(dimethylsiloxane) resin containing platinum catalyst compounds and a microencapsulated initiator (methylhydrosiloxane), embedded in a poly(dimethylsiloxane) elastomer matrix. A torsion fatigue test protocol is adopted to assess the self-healing performance of two different elastomeric matrices. Significant recovery of torsional stiffness occurs after approximately 5 h, the time required to achieve a measurable degree of cure of the healing agents. Total fatigue crack growth in a self-healing specimen is reduced by 24% in comparison to relevant controls. The retardation of growing fatigue cracks is attributed, in part, to a sliding-crack-closure mechanism, where polymerized healing agent shields the crack tip from the applied far-field stress.     

High-performance self-healing anticorrosion epoxy coating based on microencapsulated epoxy-amine chemistry

Attributed to the merits of excellent material compatibility, healing performance, and long-term stability, the self-healing system based on microencapsulated epoxy-amine chemistry is a potentially practical self-healing system for both structural and functional materials. Herein, based on the microencapsulated epoxy-amine chemistry, a self-healing anticorrosion coating was successfully developed. This self-healing coating system was modeled theoretically to explore the factors that influence the crack filling and the self-healing anticorrosion function. The established quantitative relationship shows that the filling depth of the crack in the coating is proportional to the microcapsule parameters and coating thickness, but inversely proportional to the crack width. Based on the above theoretical model, the effects of various parameters on the anticorrosion performance were experimentally studied. The actual filling of small in-situ cracks (<100 μm) generated by impact damage was semi-quantitatively characterized using scanning electron microscopy (SEM). The filling behavior is consistent with the theoretical modeling. After being healed at room temperature for 2 days upon impact damage, the formulated self-healing coatings were subjected to accelerated corrosion tests in 10 wt% sodium chloride (NaCl) solution for 2 days to observe their anticorrosion behavior. Compared to the neat epoxy coating, all the formulated self-healing epoxy coatings show evident anticorrosion function. Good self-healing anticorrosion performance was achieved by adding 10.0 wt% microcapsules with a size of 100–150 μm to the coating with a thickness of 300 μm. The results of this investigation laid a theoretical and technical foundation for the further development of both the self-healing chemistry and the self-healing anticorrosion coating.     

外援型自修复聚合物材料研究进展

综述了近年来自修复聚合物材料的研究进展,根据自修复过程是否需要外加修复剂,聚合物基复合材料自修复方法主要包括外援型自修复和本征型自修复。结合近几年最新研究成果,归纳了几种典型的外援型自修复方法,主要包括空心纤维自修复、纳米粒子自修复、微胶囊自修复（双环戊二烯修复剂体系、环氧树脂修复剂体系等）、微脉管自修复、碳纳米管自修复等,系统阐述了这几种自修复方法的修复机理、自修复体系特点及研究现状。展望了自修复材料的研究前景：优化和开发新的修复剂体系以提高修复效率、实现真正意义上的仿生材料。     

Improvement of Flame Retardant Properties of Polyurethane Composites Using Microencapsulation Technology

One kind of microencapsulated flame retardant containing melamine polyphosphate(MPP) and hydrophobic resin layer as core and shell material was synthesized by in situ polymerization technology. The structures and properties of microencapsulated MPP were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and water contact angle. Thermal behaviors of the composites containing microencapsulated MPP were analyzed by thermogravimetric analysis. Flame retardant tests indicated that the microencapsulated MPP with the polymer resin led to an improvement of the hydrophobicity. Results revealed that the flame retardancy of the composites was improved at the same fillers loading through the microencapsulation technology, which the char yields reached (~26.9wt%) and flame retardance grade (LOI-38%) with optimized MPP addition (~40%) to polymer matrix.     

高分子聚合物复合材料的自愈合研究进展

从自愈合机理出发,综述了高分子聚合物复合材料自愈合的研究进展,展望了其应用前景。     

Effect of microcapsule size on the performance of self-healing polymers

The influence of microcapsule diameter and crack size on the performance of self-healing materials is investigated. These epoxy-based materials contain embedded Grubbs' catalyst particles and microencapsulated dicyclopentadiene (DCPD). Autonomic repair is triggered by rupture of the microcapsules in response to damage, followed by release of DCPD into the crack plane where it mixes with the catalyst and polymerizes. The amount of liquid that microcapsules deliver to a crack face is shown to scale linearly with microcapsule diameter for a given weight fraction of capsules. In addition, self-healing performance reaches maximum levels only when sufficient healing agent is available to entirely fill the crack. Based on these relationships, the size and weight fraction of microcapsules can be rationally chosen to give optimal healing of a predetermined crack size. By using this strategy, self-healing is demonstrated with smaller microcapsules and with lower weight fractions of microcapsules than have been possible in previous self-healing systems.