NBR／PVC发泡与阻燃材料的研究进展

综述了最近十几年的丁腈橡胶（NBR）、聚氯乙烯（PVC）的发泡材料和阻燃材料的研究进展。分别对NBR／PVC发泡材料、NBR／PVC阻燃材料和NBR／PVC泡沫阻燃材料的研究进展进行了总结,并指出NBR／PVC泡沫弹性体的阻燃技术发展缓慢,未来发展空间很大,将会成为NBR／PVC的一个新的发展趋势,应该受到重视。     

Micrometer‐Thick Graphene Oxide–Layered Double Hydroxide Nacre‐Inspired Coatings and Their Properties

Robust, functional, and flame retardant coatings are attractive in various fields such as building construction, food packaging, electronics encapsulation, and so on. Here, strong, colorful, and fire‐retardant micrometer‐thick hybrid coatings are reported, which can be constructed via an enhanced layer‐by‐layer assembly of graphene oxide (GO) nanosheets and layered double hydroxide (LDH) nanoplatelets. The fabricated GO–LDH hybrid coatings show uniform nacre‐like layered structures that endow them good mechanic properties with Young's modulus of ≈18 GPa and hardness of ≈0.68 GPa. In addition, the GO–LDH hybrid coatings exhibit nacre‐like iridescence and attractive flame retardancy as well due to their well‐defined 2D microstructures. This kind of nacre‐inspired GO–LDH hybrid thick coatings will be applied in various fields in future due to their high strength and multifunctionalities.     

MCA-MMT的制备及其对玻璃纤维增强聚丙烯复合材料阻燃性能的影响

为了提高玻璃纤维(GF)增强聚丙烯(PP)复合材料(GF/PP)的阻燃性能,通过在蒙脱土(MMT)悬浮液中进行三聚氰胺氰尿酸盐(MCA)分子自组装制备了新型协效成炭剂MCA-MMT,并采用FTIR、XRD、SEM和TGA对MCA-MMT的结构及热性能进行了表征;将MCA-MMT、无卤膨胀型阻燃剂与GF/PP熔融共混制备了阻燃复合材料MCA-MMT/(GF/PP),通过极限氧指数(LOI)测试、垂直燃烧试验和锥形量热测试研究了MCAMMT对GF/PP的阻燃效果和阻燃机制,并测试了复合材料的力学性能。结果表明:MMT的加入会影响氰尿酸和三聚氰胺在MCA合成过程中的氢键作用,干扰和抑制大平面氢键网络的形成,减少MCA氢键复合体的分子体积,使颗粒变小。MCA-MMT/(GF/PP)的UL-94防火等级达到V-0级,LOI为31.3%。MCA-MMT的阻燃效率高于传统MCA的,可降低材料燃烧的热释放程度和总烟释放量,使复合材料的阻燃性能提高,其阻燃机制为片层结构的MMT可提高MCA的成炭量,使MCA-MMT/(GF/PP)燃烧后能形成致密的残留炭层。MCA-MMT/(GF/PP)的拉伸、冲击强度与MCA/(GF/PP)的相比并未下降。     

A Liquid‐Metal–Elastomer Nanocomposite for Stretchable Dielectric Materials

Stretchable high‐dielectric‐constant materials are crucial for electronic applications in emerging domains such as wearable computing and soft robotics. While previous efforts have shown promising materials architectures in the form of dielectric nano‐/microinclusions embedded in stretchable matrices, the limited mechanical compliance of these materials significantly limits their practical application as soft energy‐harvesting/storage transducers and actuators. Here, a class of liquid metal (LM)–elastomer nanocomposites is presented with elastic and dielectric properties that make them uniquely suited for applications in soft‐matter engineering. In particular, the role of droplet size is examined and it is found that embedding an elastomer with a polydisperse distribution of nanoscale LM inclusions can enhance its electrical permittivity without significantly degrading its elastic compliance, stretchability, or dielectric breakdown strength. In contrast, elastomers embedded with microscale droplets exhibit similar improvements in permittivity but a dramatic reduction in breakdown strength. The unique enabling properties and practicality of LM–elastomer nanocomposites for use in soft machines and electronics is demonstrated through enhancements in performance of a dielectric elastomer actuator and energy‐harvesting transducer.     

Novel Applications of Fullerenes in Thermal Management Systems

Abstract

The new potential applications of fullerenes (buckyballs), such as advanced thermal protection coatings, fire retardant materials and cryogenic insulation materials were investigated. Based on experimental results, it was shown that due to low thermal conductivity and high emissivity, micron‐scale fullerene films were capable of withstanding elevated temperatures (up to 800°C) resulting in over 100°C temperature decrease on the “cold” surface of the underlying substrate. In addition, it was shown that due to the high heat of sublimation and low ablation rates, fullerenes can provide excellent ablative cooling in the temperature range of 600–1000°C. Consequently, unique flame‐retardant ability of fullerenes was demonstrated.     

膨胀阻燃多层膜改性苎麻织物/苯并噁嗪树脂层压板的制备及性能

为提高苎麻织物作为复合材料增强体时的阻燃性能,首先,采用层层组装法在苎麻织物表面构筑了氨基化多壁碳纳米管（MWCNT）-聚磷酸铵（APP）与聚乙烯亚胺（PEI）-APP膨胀阻燃多层膜;然后,将改性后的苎麻织物与苯并噁嗪树脂复合制备了苎麻织物/苯并噁嗪树脂层压板,并研究了层压板的热降解行为、阻燃性能与力学性能。结果表明:与纯苎麻织物/苯并噁嗪树脂层压板相比,含MWCNT-APP与PEI-APP膨胀阻燃多层膜的层压板热释放速率峰值由106.6 W·g-1降低至53.4 W·g-1和53.0 W·g-1,总热释放量由12.3 kJ·g-1降低至7.6 kJ·g-1和9.0 kJ·g-1,极限氧指数由23.5提高至27.2和27.0,UL94级别由无级别提高至V-0和V-1级,弯曲强度由81 MPa提高至122 MPa和143 MPa,弯曲断裂伸长率由1.2%提高至1.4%和1.7%,拉伸性能也得到了一定的改善。所得结论表明使用MWCNT-APP与PEI-APP膨胀阻燃多层膜可在提高层压板阻燃性能的同时,改善其力学性能。      

阻燃聚酯/蒙脱土纳米复合材料的制备及燃烧性能

采用直接酯化法,将共聚型阻燃剂羧乙基苯基次磷酸(CEPP)和对苯二甲酸以及乙二醇混合后酯化,在酯化产物中加入经过有机改性的蒙脱土,缩聚制备了阻燃聚酯/蒙脱土纳米复合材料(PET/MMT/CEPP)。用FT-IR、CONE对制得的复合材料进行了分析和研究,结果表明阻燃剂和聚酯发生了聚合反应,但加入的阻燃剂和蒙脱土在一定程度上降低了聚酯的特性黏度;PET/MMT/CEPP中的蒙脱土和阻燃剂起到了良好的协同阻燃效果,复合材料的阻燃性能有明显提高。     

Protective coatings for carbon fibers

Protective refractory nanocoatings on carbon bundles and tapes have been investigated. Processes have been developed for growing thin layers of refractory oxides—alumina, zirconia, and silica—on continuous carbon fibers and tapes using sol-gel processing. ZrC/ZrO₂ bilayer coatings have been produced by chemical vapor transport. The surface morphology, phase composition, and elemental composition of the coatings have been studied by x-ray diffraction, high-resolution scanning electron microscopy, and qualitative energy-dispersive x-ray microanalysis. The results demonstrate that the refractory oxide coatings are homogeneous along the length and perimeter of individual fibers and adhere well to the fiber surface, with no peeling. Their thickness is within 200–300 nm. The effect of the nature of the coating on the oxidation resistance of carbon materials is analyzed.     

胶合板表面层层自组装聚磷酸铵-壳聚糖/氮化硼及其阻燃性能

以杨木胶合板为研究对象,以聚磷酸铵-壳聚糖/氮化硼(APP-CS/BN)为阻燃涂层,通过层层自组装的方法将涂层整理到杨木胶合板上,以赋予胶合板一定的阻燃性能。FTIR和SEM结果显示,APP-CS/BN涂层在胶合板表面组装形成膜结构,组装膜均匀分布在材料表面。锥型量热仪(CONE)燃烧测试表明,与未经处理的胶合板相比,APP-CS/BN自组装涂层能有效延长胶合板点燃时间(TTI),降低胶合板的热释放速率(HRR)和总热释放量(THR),同时增加材料燃烧后成炭量。随着自组装涂层层数的增加,15层处理材、20层处理材、25层处理材的点燃时间较未处理材分别提升了100%、105%和125%;热释放速率峰值(Pk-HRR)较未处理材分别降低10.15%、22.34%和31.82%;阻燃处理杨木胶合板的THR,较未处理材分别降低2.89%、13.68%和15.32%;未处理材、15层处理材、20层处理材、25层处理材燃烧后成炭率依次为18.55%、24.07%、26.04%和27.65%。随着自组装层数的增加,杨木胶合板的阻燃性能随之增加,但当自组装层数由20层至25层时,胶合板阻燃能力提升的幅度变缓慢。本研究中,阻燃胶合板适宜自组装涂层数为20-25层。      

一种膨胀阻燃PP体系及其燃烧性能

制备了一种阻燃聚丙烯/膨胀阻燃剂(IFR)/蒙脱土(MMT)膨胀阻燃体系,研究了不同阻燃组分含量对体系阻燃性能的影响。结果表明,阻燃剂总添加量为30%,其中的成炭剂和聚磷酸铵(APP)的配比为1∶2时,体系的极限氧指数为29%,垂直燃烧试验(UL-94)达到V-2级;而在上述体系中添加0.5%的MMT时,体系的LOI提高到31%,垂直燃烧试验(UL-94)通过V-0级,表现出较好的协同阻燃效果。采用扫描电境(SEM)和红外光谱(FT-IR)对体系的固相残炭进行了观察和分析,探讨了可能的阻燃机理。     

阻燃剂及其阻燃机理的研究现状

近来关于阻燃剂及其阻燃机理越来越受人们的关注.综述了卤系、磷系、氮系、铝镁系、粘土类和膨胀石墨阻燃剂在高分子材料中的阻燃机理及其研究现状,并提出了增加复合材料在燃烧过程中的成炭倾向是今后聚合物阻燃设计的新思路.     

Conformal Nanocoatings with Uniform and Controllable Thickness on Microstructured Surfaces: A General Assembly Route

Assembling nanoparticles (NPs) on various surfaces are intensively investigated for the construction of functional nanocoatings; however, it is still a challenge to fabricate conformal nanocoatings uniformly on surfaces having micro‐ or nanostructures. Herein, it is demonstrated that the negatively charged SiO₂ NPs and the positively charged silicon coupling agent can be assembled layer‐by‐layer on the microstructures based on the combination of electrostatic interaction and condensation reaction. Conformal nanocoatings with controllable thickness are formed on the microstructured surfaces with different compositions and morphologies. The formation mechanism is confirmed by using quartz crystal microbalance with dissipation (QCM‐D) to study the assembly process in real time. The universality of this method is illustrated by using other reactive building blocks with opposite charge to build up the conformal nanocoatings. Application in the preparation of antireflective nanocoatings on nonplanar optical materials is demonstrated. This simple, versatile, and scalable strategy for the preparation of conformal nanocoatings is promising for practical applications.     

基于层层组装法构建阻燃天然纤维素纤维织物的研究进展

利用层层组装(LBL)法构建阻燃天然纤维素纤维织物是基于相反电荷聚电解质的物理吸附作用,在织物表面交替沉积而成多层膜的一种新型阻燃改性方法。与传统方法相比,LBL法可以在基体与外部环境之间构建阻燃多层膜,从而直接干扰燃烧过程;尤其是通过对组装条件和过程的调节,可以方便地控制多层膜的质量、厚度和元素组成,进而对阻燃性能进行有效调控。总结了近年来国内外基于LBL法构建纳米材料-纳米材料、纳米材料-聚电解质及聚电解质-聚电解质阻燃天然纤维素纤维织物的研究进展,介绍了本课题组在苎麻织物表面构建氨基化碳纳米管-聚磷酸铵和聚乙烯亚胺-聚磷酸铵膨胀型阻燃涂层方面所做的探索性工作,展望了其未来的发展趋势。     

Highly Safe Electrolyte Enabled via Controllable Polysulfide Release and Efficient Conversion for Advanced Lithium–Sulfur Batteries

Conventional lithium–sulfur batteries often suffer from fatal problems such as high flammability, polysulfide shuttling, and lithium dendrites growth. Here, highly‐safe lithium–sulfur batteries based on flame‐retardant electrolyte (dimethoxyether/1,1,2,2‐tetrafluoroethyl 2,2,3,3‐tetrafluoropropyl ether) coupled with functional separator (nanoconductive carbon‐coated cellulose nonwoven) to resolve aforementioned bottle‐neck issues are demonstrated. It is found that this flame‐retardant electrolyte exhibits excellent flame retardancy and low solubility of polysulfide. In addition, Li/Li symmetrical cells using such flame‐retardant electrolyte deliver extraordinary long‐term cycling stability (less than 10 mV overpotential) for over 2500 h at 1.0 mA cm^?2 and 1.0 mAh cm^?2. Moreover, bare sulfur cathode–based lithium–sulfur batteries using this flame retardant electrolyte coupled with nanoconductive carbon‐coated cellulose separator can retain 83.6% discharge capacity after 200 cycles at 0.5 C. Under high charge/discharge rate (4 C), lithium–sulfur cells still show high charge/discharge capacity of ≈350 mAh g^?1. Even at an elevated temperature of 60 °C, discharge capacity of 870 mAh g^?1 can be retained. More importantly, high‐loading bare sulfur cathode (4 mg cm^?2)–based lithium–sulfur batteries can also deliver high charge/discharge capacity over 806 mAh g^?1 after 56 cycles. Undoubtedly, the strategy of flame retardant electrolyte coupled with carbon‐coated separator enlightens highly safe lithium–sulfur batteries at a wide range of temperature.     

无卤本质阻燃环氧树脂

本质阻燃高聚物阻燃效能持久,不存在挥发、溶出及迁移的问题,且可实现分子内协同阻燃效应,又为环境兼容,故近年日益崭露头角。文中论述无卤本质阻燃环氧树脂的一些制备方法及性能,且涉及的主要是分子中含DOPO侧基及含磷酸酯基的两类本质阻燃环氧树脂。     

纳米技术在材料阻燃改性中的应用

介绍了纳米技术在阻燃材料中的应用进展。层状硅酸盐、层状双氢氧化物、碳纳米管等制备的聚合物／纳米复合材料，其热稳定性有所提高，但要和阻燃剂协同使用才能达到最佳的阻燃效果。常规阻燃剂的纳米化不仅可以提高阻燃效率，还可降低阻燃剂的添加量，改善阻燃材料的物理机械性能。     

膨胀型阻燃剂的研究进展

随着易燃高分子材料的广泛应用,阻燃剂也得到了广泛的应用,同时对阻燃剂的阻燃性、相容性等特性也有了更高的要求。膨胀型阻燃剂具有阻燃效率高、低烟、低毒等优点,因此成为阻燃剂的重要发展方向。简单介绍了膨胀型阻燃剂的阻燃机理,重点综述了近年来国内外膨胀型阻燃剂的最新研究进展和阻燃剂生产的新技术。最后指出了目前膨胀型阻燃剂研究存在的问题,也对该领域未来的研究方向提出了建议。     

磷系阻燃剂的微胶囊化及其在聚合物中的应用研究进展

磷系阻燃剂是阻燃效率较高的一类无卤阻燃剂,但同时存在易吸水,与基体相容性差,热稳定性不好等缺点。微胶囊化是近年来克服这些缺点的有效途径。通过分子设计不同的囊壳对阻燃剂进行微胶囊化改性,不仅可以改善阻燃剂的物理性质,还可以提高阻燃材料的阻燃性能。文中介绍了三聚氰胺-甲醛树脂、聚氨酯、环氧树脂、有机硅以及纤维素等不同囊壳材料对微胶囊化的阻燃剂及阻燃复合材料性能的影响,研究表明微胶囊化改性后的阻燃剂的耐水性、热稳定性与基体的相容性以及阻燃材料的力学性能均得到有效的提高。