动态力学分析技术在类玻璃高分子性能表征中的应用

类玻璃高分子因结合了热塑性材料可塑形变的能力以及热固性材料永久定型的特征,目前在高分子研究领域备受青睐。采用动态力学分析技术可深入研究此类材料的动态黏弹性和流变行为,建立类玻璃高分子交联网络、动态键等结构与材料性能间的关系。本文重点阐述动态力学分析技术在类玻璃高分子的动态黏弹性、交联网络结构、流变行为、膨胀及形状记忆行为等方面的表征应用,为此类材料的结构设计、性能评价以及加工应用等从测试表征角度提供参考。     

晶须及其在高分子材料中的应用

简要介绍了目前高分子材料改性中常用的晶须，如钛酸钾晶须、硼酸铝晶须、氧化锌晶须等，主要对其在橡胶、热塑性弹性体、热塑性树脂以及热固性树脂中的应用作了详尽论述。     

类玻璃高分子的再加工

类玻璃高分子(vitrimer)是一类含有动态共价键的共价交联聚合物网络, 结合了热固性聚合物和热塑性聚合物的优点. 在外界刺激作用下, 类玻璃高分子的动态共价键能够可逆断裂及形成, 而交联密度不会发生变化, 这种独特的性质使其能在保持三维交联网络结构的同时, 实现再加工、回收再利用、焊接和愈合等功能. 因此, 类玻璃高分子有望解决传统热固性聚合物无法进行再加工和回收再利用等问题, 推进资源的循环利用和社会可持续发展. 重点介绍了类玻璃高分子不同的再加工方式, 包括热加工、光热加工、电热加工和小分子辅助加工, 并对各个加工方式的原理、特点和应用进行总结. 最后, 对类玻璃高分子再加工的发展进行了展望.     

环氧树脂体系固化反应及其复合材料介电性能

环氧树脂是一类综合性能优异的热固性高分子材料，作为胶粘剂、复合材料用树脂基体、涂料等形式广泛应用于电子电气、机械制造、化工防腐、航空航天等众多领域中，成为各工业领域中不可缺少的基础材料。本文综述了本研究室在咪唑／环氧树脂体系，稀土有机化合物、叔胺羧酸复盐／酸酐／环氧树脂体系，氰酸酯／环氧树脂体系，硼胺络合物／环氧树脂体系的固化反应机理、固化反应动力学及其固化物结构与性能关系，纤维含量、排列方向、偶联剂种类等对玻璃纤维增强环氧树脂基复合材料及其界面介电性能的影响等6个方面的研究进展。     

热感应型形状记忆高分子材料

热感性型形状记忆高分子材料（thermostimulative shape memory polymer，TSMP）不仅具有形变量大、赋形容易，形状回复温度便于调节、加工方便等特点，而且种类丰富。按其固定相结构的不同，可分为热塑性TSMP和热固性TSMP。本文从表征方法、记忆机理等方面简述了热感应型形状记忆高分子材料最新的发展，其中重点阐述了近期热感应型形状记忆可降解高分子的形状记忆原理及其应用。     

环氧树脂增韧改性的研究进展

环氧树脂作为主要的热固性树脂之一,性能优异,应用广泛。但由于其固化交联密度高,脆性大的缺点,环氧树脂的实际应用受到了极大地限制。因此,环氧树脂的增韧改性成为了人们研究的重点。本文主要从橡胶、聚硅氧烷、热塑性塑料、树枝状聚合物、嵌段聚合物、纳米填料这几种主要增韧材料出发,系统综述了近几年来环氧树脂增韧改性的研究进展,简要阐述了各种材料的增韧机制,并对环氧树脂增韧改性的研究进行了分析与展望。     

一种液晶环氧增韧环氧树脂的研究

环氧树脂具有优异的机械性能 ,耐高温以及良好的加工工艺性 .被广泛用于机械、航天、船舶等领域 .由于环氧树脂固化后断裂延伸率小 ,脆性大 ,使其应用受到了一定的限制 .为此 ,国内外学者对环氧树脂进行了大量的改性研究工作 .用含有“柔性链段”的固化剂固化环氧 ,在交联网络中引入柔性链段[1] ;在环氧基体中加入橡胶弹性体[2 ] 、热塑性树脂[3 ,4] 、液晶聚合物[5,6] 等分散相或用热固性树脂连续贯穿于环氧树脂网络中形成互穿、半互穿网络结构[7] ,以改善环氧树脂的韧性 .本文采用液晶环氧化合物原位复合增韧环氧树脂 ,考察了液晶环氧对环…     

热塑性/热固性聚合物共混体系研究——乙炔端基砜/聚砜共混物的动态固化动力学

近年来,半互穿聚合物网络(SIPN)概念被用来研制能结合热塑性聚合物的加工性和热固性聚合物的高温性能的大分子体系,用于复合材料耐高温树脂基体。例如:乙炔端基酰亚胺低聚物与热塑性聚酰亚胺基SIPN,线性聚酰亚胺与热固性双马来酰亚胺基SIPN以及热塑性树脂与双腈基SIPN已有报道。研究结果表明共混物起到协同作用,易于加工并具有优异的性能。乙炔端基砜(ATS)树脂具有与聚砜树脂相类似的结构,被认为在将来代替环氧用于高性能粘合剂和复合材料树脂基体的候选者之一。其另     

氢键交联超分子聚合物材料：从结构性能到功能应用

高分子材料的大量消耗与持续积累已经在全球范围内造成了严重的环境污染与资源浪费.发展可修复、可循环、可降解和可回收的新一代高分子材料是解决上述挑战的根本途径.基于动态可逆的非共价键将聚合物链段进行交联可以有效地构建这些材料.本专论系统总结了我们课题组在氢键交联超分子聚合物材料方面的系列研究进展.基于多重氢键的协同性与动态性、氢键与动态共价键的协同,以及材料微相结构的调控,发展了系列兼具高强度与高韧性的超分子聚合物材料,实现了材料的修复、循环、降解与回收;不仅突破了非共价交联高分子材料力学性能弱的瓶颈,而且化解了高分子材料强度与韧性的矛盾.相关研究为发展传统高分子材料的可持续替代品提供了新的思路.同时,发展了系列基于氢键交联的功能超分子聚合物材料,展示了其在柔性电子、固态锂电池及水下黏合剂等方面的应用.     

聚醚链段长度对氨基聚醚-环氧树脂力学性能的影响

以柔性端氨基聚醚(BATPE)和双酚A环氧树脂(DGEBA)为原料, 制备了无微相分离结构的无定型AB交联热固性树脂. 测试了3种不同聚乙二醇(PEG)链段长度(M_PE)的BATPE-DGEBA环氧树脂固化产物的应力-应变曲线、动态力学温度谱和冲击断面形貌. 结果表明, 在环氧树脂交联网络中引入两端与DGEBA化学连接的PEG链段能避免微相分离结构的生成, 有利于提高DGEBA链段的应变松弛速率. 增加M_PE, 一方面能降低环氧树脂固化产物的玻璃化转变温度和室温下的刚度和拉伸强度, 增加韧性(包括冲击强度和拉伸韧性)、断裂应变和模量损耗因子; 另一方面也能提高固化产物在低温下的储存模量. 优化M_PE可制备出在中低温下同时具有优异的拉伸强度、模量、断裂应变和冲击性能的BATPE-DGEBA环氧树脂.     

高性能可回收环氧树脂及其复合材料的制备与性能研究

采用戊二酸酐为固化剂,乙酰丙酮锌为催化剂制备了一种综合性能优异的高性能可回收环氧树脂.系统研究了固化剂及催化剂含量对树脂结构、热学及动态性能的影响,实现了树脂组成的优化设计.基于酯交换反应的热可逆性,制备的vitrimer树脂通过物理热压方法可实现良好回收,力学强度保持率可达80%.采用RTM工艺制备的碳纤维织物增强vitrimer树脂复合材料表现出与传统热固性树脂基复合材料相当的力学性能,并且通过醇类溶剂热降解树脂的方法,可实现复合材料中碳纤维的高效无损回收,回收率近100%.     

Bio‐based epoxy vitrimers: Reprocessibility,controllable shape memory,and degradability

The research activities in the development of recyclable and reprocessable covalently crosslinked networks, and the construction of polymers from renewable resources are both stemmed from the economical and environmental problems associated with traditional thermosets. However, there is little effort in combination of these two attractive strategies in material designs. This article reported a bio‐based vitrimer constructed from isosorbide‐derived epoxy and aromatic diamines containing disulfide bonds. The resulted dynamic epoxy resins showed comparable thermomechanical properties as compared to similar epoxy networks cured by traditional curing agent. Rheological tests demonstrated the fast stress relaxation of the dynamic network due to the rapid metathesis of disulfide bonds at temperature higher than glass transition temperature. This feature permitted the recycling and reprocessing of the fragmented samples for several times by hot press. The dynamic epoxy resins also exhibited shape‐memory effect, and it is demonstrated that the shape recovery ratio could be readily adjusted by controlling the stress relaxation in the temporary state at programming temperature. Moreover, the degradability of the dynamic epoxy resins in alkaline aqueous solution was also demonstrated. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1790–1799     

可多次使用的液晶型类玻璃高分子

通过高温下酯交换反应的进行,含酯键的液晶型类玻璃高分子(liquid crystalline vitrimer),能够通过简单拉伸进行取向,获得随温度变化可逆伸缩的智能材料.在目前已报道的此类主链型高分子中,酯交换剧烈发生需要的临界温度(Tv),与液晶弹性体发生可逆形变的温度(Ti,即液晶相-各向同性相转变温度)相隔较近,导致材料的使用温度范围比较窄,而且多次升降温后,取向及可逆形变会消失.为解决此问题,本文在原来体系的基础上,通过共聚合另外一种液晶基元,有效地降低了Ti,从而拓宽Ti与Tv之间的距离.这不仅使材料的使用次数明显增加,还能延长此类液晶弹性体的使用期限.     

Reprocessible Epoxy Networks with Tunable Physical Properties: Synthesis,Stress Relaxation and Recyclability

In order to extend the application of epoxy vitrimer,1,4-cyclohexanedicarboxylic acid (CHDA) was used as a co-curing agent and structure modifier for sebacic acid (SA) cured diglycidyl ether of bisphenol A (DGEBA) epoxy vitrimer to tailor the mechanical properties of epoxy vitrimers with 1,5,7-triazabicylo[4.4.0]dec-5-ene (TBD) as a transesterification catalyst.The glass transition temperature (Tg) ofvitrimer increased gradually with the increase in CHDA content.Vitrimers behaved from elastomer to tough and hard plastics were successfully achieved by varying the feed ratio of CHDA to SA.Both the Young's modulus and storage modulus increased apparently with the increase in CHDA content.Stress relaxation measurement indicated that more prominent stress relaxation occurred at elevated temperatures and the stress relaxation decreased with the increase of CHDA content due to the reduced mobility of the vitrimer backbone.The vitrimers showed excellent recyclability as evidenced by the unchanged gel fraction and mechanical properties after compression molded for several times.With tunable mechanical properties,the epoxy vitrimers may find extensive potential applications.     

Epoxy polymers based on functional adamantane derivatives

The main routes for modification of epoxy polymers with functional adamantane derivatives consisting of four saturated cycles are considered. It is shown that the high thermodynamic stability and rigidity of adamantane structure define a complex of properties of epoxy polymers and materials, as compared to the known polymers based on acyclic epoxy resins.     

含三氰乙烯基强吸电子基团的环氧树脂基非线性光学聚合物的合成

非线性光学聚合物材料及其在聚合物电光调制器中的应用是目前国内外研究的前沿。环氧树脂类聚合物具有很好的成膜性及可化学交联性能,是一类非常好的非线性光学聚合物的基体材料。本论文从分子设计的角度出发,将含三氰乙烯基强吸电子取代基及噻吩芳杂环共轭结构非线性光学生色团成功引入环氧树脂类聚合物,并在生色团侧基上引入甲基取代基。结果表明,苯胺残基中侧位甲基取代基对于先驱聚合物的亲电取代反应程度及最后聚合物的紫外-可见光最大吸收波长均有一定的影响,对于没有侧甲基的BP-TA-TC和一个侧甲基取代基的BP-3-TA-TC其官能化度均可以达到80%以上,而对于含两个甲基取代的BP-3,5-TA-TC先驱聚合物其官能化度则相对较低(低于10%)。随着甲基取代数目的增多,最后非线性光学聚合物的最大吸收波长也有不同程度的蓝移。     

The Structure and Moisture Stability of the Matrix Phase in Glass-Reinforced Epoxy Composites

The utilization of reinforced plastic composites is generally limited by their sensitivity to long-term environmental exposure. Glass-reinforced thermosetting polymers in particular are detrimentally affected, reversibly and/or irreversibly, by exposure to water vapor or liquid water. A reinforced composite consists of three mutually interacting regions: fiber, matrix, and the fiber/ matrix interface. Each region may, for purposes of convenience, be further subdivided according to its location or properties. Most common is the listing of regions comprising the “interface”: glass/ coupling agent interface, the coupling agent polymer itself, and the coupling agent/matrix interface. Even the amorphous cross-linked matrix nearby the filler is believed to possess properties dissimilar to those of the bulk. Each region and subregion is altered by moisture exposure to some extent; at this time studies on composite stability still focus on determining which regions are most affected by the environment and on the mechanisms of those effects, as well as on devising systems with minimal environmental sensitivity. Moisture effects on glass-reinforced epoxy composites, the most common of the reinforced plastic systems, will be emphasized in this paper. Multifunctional epoxy resins are typically cross-linked by acid anhydrides, forming 3-D polyesters, and by amine functional compounds, yielding 3-D amine-ether polymers. There are many structural varieties; the same hydrothermal degradation mechanisms apply universally, and hereafter the term “epoxy” matrix will be employed. The stability of the glass reinforcement itself and of the interface will first be briefly reviewed as a prelude to a more detailed consideration of the reversible and irreversible moisture effects on the cross-linked epoxy matrix.     

Photopolymers for Rapid Prototyping of Soluble Mold Materials and Molding of Cellular Biomaterials

To substitute cross-linked photopolymers in rapid prototyping of mold materials and therefore extend the range of materials which can be casted, organo-soluble photopolymers were developed. Branched bisalkylacrylamides were suitable as base component for such formulations, due to their high reactivity, good mechanical properties, and excellent solubility of the formed polymers. These molding materials were used to prepare cellular biocompatible materials which could be used as bone replacement materials. Biocompatible crosslinkers based on methacrylates from hydrolyzed gelatine or lactic acid ethyleneglycol blockcopolymers and commercially available reactive diluents are the base components of such a formulation. Biocompatibility was investigated by osteoblast-like cells. Cellular biocompatible parts were obtained by thermal polymerization in soluble mould materials prepared by 3D-photoshaping.     

Photopolymers for Rapid Prototyping of Soluble Mold Materials and Molding of Cellular Biomaterials

Summary. To substitute cross-linked photopolymers in rapid prototyping of mold materials and therefore extend the range of materials which can be casted, organo-soluble photopolymers were developed. Branched bisalkylacrylamides were suitable as base component for such formulations, due to their high reactivity, good mechanical properties, and excellent solubility of the formed polymers. These molding materials were used to prepare cellular biocompatible materials which could be used as bone replacement materials. Biocompatible crosslinkers based on methacrylates from hydrolyzed gelatine or lactic acid ethyleneglycol blockcopolymers and commercially available reactive diluents are the base components of such a formulation. Biocompatibility was investigated by osteoblast-like cells. Cellular biocompatible parts were obtained by thermal polymerization in soluble mould materials prepared by 3D-photoshaping.     

Thermal analysis characterization of isosorbide-containing thermosets

Sugar-based new monomers, polymers, and low molar mass additives have emerged as an exciting topic on green chemistry research, due to the worldwide focus on sustainable material. Isosorbide and its isomers, as ??Generally Recognized as Safe?? GRAS materials, possess unique stereochemistry and molecular geometry suitable for making cost-effective chemicals and polymers. With growing awareness of bisphenol A (BPA) as a xenoestrogen, isosorbide and its isomers holding the remarkable chemical properties and attractive price can be attached to glycidyl ether to make crosslinkable epoxy resin monomers with similar properties to BPA diglycidyl ether. By adding the hydrophobic functional group into the backbone of isosorbide epoxy or adjusting the amount and type of crosslinker, the mechanical properties and the water uptake ratios (from <1 to >50?wt%) of the isosorbide-derived epoxies could be optimized for different applications. The high water uptake epoxy with controllable biodegradation rate could be used as a drug delivery system or extracellular matrix for biomedical applications while the low water uptake epoxy with strong mechanical properties could be used for can coatings, bone cements, and other industrial additives and adhesives. The chemical structures and properties of the synthesized epoxy monomers and polymers were characterized by DSC, TG, and ¹H NMR.