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epoxy microcapsules for high-performance self-healing materials using a novel method via integrating electrospraying and interfacial polymerization

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Journal of Materials Science & Technology 2022年第17期112卷 59-67页

作者： He Zhang Kaibin Xiao Zhilin Lin Shengyu Shi Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing South China University of TechnologyGuangzhou 510641China National Engineering Research Center of Novel Equipment for Polymer Processing Key Laboratory of Polymer Processing Engineering(SCUT)Ministry of EducationSouth China University of TechnologyGuangzhou 510641China

The high-efficiency fabrication of high-quality microcapsules containing epoxy is crucial to the further development of the potential practical self-healing epoxy systems based on microencapsulated two-part epoxy-amine chemistry.Herein,a novel microencapsulation technique based on non-equilibrium droplets via integrating electrospraying and interfacial polymerization(ES-IP)was established to efficiently microencapsulate epoxy monomers.The ES-IP technique,consisting of three continuous steps,i.***.electrospraying to massively generate droplets,enwrapping every single droplet through instant interfacial polymerization,and thickening shell at an elevated temperature,has great flexibility to regulate the microencapsulation process and the microcapsule quality.The fabricated core-shell structured epoxy microcapsules(Ep-MCs)were comprehensively characterized for their properties,showing that they have high cleanness with rare impurities,controllable and tunable size,good thermal stability and tightness,and high effective core fraction.The high-quality Ep-MCs were adopted to formulate a self-healing epoxy based on the microencapsulated epoxy-amine chemistry.The highest healing efficiency,in terms of the recovered mode I fracture toughness,of 110±17%was achieved after being healed at room temperature(~25℃)for 48 h.While the developed ES-IP technique facilitates the microencapsulation technique based on non-equilibrium droplets,the fabricated high-quality Ep-MCs greatly promote the further developments of the practical self-healing materials.

关键词： epoxy Microcapsule Electrospraying Interfacial polymerization Self-healing

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Vertically Aligned Silicon Carbide Nanowires/Boron Nitride Cellulose Aerogel Networks Enhanced Thermal Conductivity and Electromagnetic Absorbing of epoxy Composites

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Nano-Micro Letters 2022年第7期14卷 209-227页

作者： Duo Pan Gui Yang Hala MAbo-Dief Jingwen Dong Fengmei Su Chuntai Liu Yifan Li Ben Bin Xu Vignesh Murugadoss Nithesh Naik Salah MEl-Bahy Zeinhom MEl-Bahy Minan Huang Zhanhu Guo Key Laboratory of Materials Processing and Mold(Zhengzhou University) Ministry of EducationNational Engineering Research Center for Advanced Polymer Processing TechnologyZhengzhou UniversityZhengzhou 450002People’s Republic of China Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia Mechanical and Construction Engineering Faculty of Engineering and EnvironmentNorthumbria UniversityNewcastle upon Tyne NE18STUK Integrated Composites Laboratory(ICL) Department of Chemical and Biomolecular EngineeringUniversity of TennesseeKnoxvilleTN 37996USA Advanced Materials Division Engineered Multifunctional Composites(EMC)Nanotech LLCKnoxvilleTN 37934USA College of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024People’s Republic of China Department of Mechanical and Manufacturing Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipalKarnataka 576104India Department of Chemistry Turabah University CollegeTaif UniversityP.O.Box 11099Taif 21944Saudi Arabia Department of Chemistry Al-Azhar UniversityNasr CityCairo 11884Egypt

With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel(CA) with highly enhanced thermal conductivity(TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires(SiC NWs)/boron nitride(BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m^(-1) K^(-1) at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy(EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 10^(11) Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of-21.5 dB and a wide effective absorption bandwidth(<-10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.

关键词： epoxy Ice template Vertical alignment Thermal conductivity Multifunctionality

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Reducing damage extent of epoxy coating on magnesium substrate by Zr-enhanced PEO coating as an effective pretreatment

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Journal of Magnesium and Alloys 2023年第2期11卷 641-656页

作者： Z.Jamshidipour M.Toorani M.Aliofkhazraei M.Mahdavian Department of Materials Engineering Tarbiat Modares UniversityTehranIran Department of Surface Coatings and Corrosion Institute for Color Science and Technology(ICST)TehranIran

This research was undertaken to study the effect of Zr-enhanced plasma electrolytic oxidation(PEO) as a pretreatment on the corrosion performance of epoxy coating applied on Magnesium in 3.5 wt.% Na Cl solution. The parameters of delamination index along with coating damage index were extracted through electrochemical impedance spectroscopy(EIS) tests to determine how Zr may affect the corrosion protection of duplex PEO/epoxy coated samples. Pull-off adhesion tests were also accomplished to form a better understanding of Zr-enhanced PEO coating’ function. According to the obtained results, the presence of Zr can reduce the damage to the coating system by almost twice.

关键词： Magnesium EIS Pretreatment PEO epoxy Zirconyl nitrate

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Fabrication and Characterization of Banana Pseudostem Fibre Reinforced epoxy Hybrid Composite Using Al_(2)O_(3) as Filler

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Journal of Bionic Engineering 2023年第4期20卷 1737-1746页

作者： Ankit Samal Sanjeev Kumar Manish Bhargava Barnik Saha Roy Mechanical Engineering Department National Institute of Technology AgartalaJiraniaTripura799046India Mechanical Engineering Department Subharti Institute of Technology and EngineeringMeerutUttar Pradesh250005India

Natural fibre-reinforced composites are now becoming incredibly common in various products because of their comparable qualities to conventional materials.Due to its availability,superior mechanical qualities,and low cost,banana pseudostem is extensively used in various applications requiring natural fibres.This study investigates the physical and mechanical properties of epoxy composites reinforced with banana pseudostem fibres that contain Al_(2)O_(3) particulate.In order to produce composites with fibre and filler loadings,manual hand layup was used.Fibre and filler loading effects on composite properties were studied in experiments.The results of the investigations demonstrate that proportion of Al_(2)O_(3) in composites significantly influences their mechanical and physical properties.Additionally,the composite with a fibre content of 30%shows improved mechanical proportions and hardness.Thermogravimetric analysis was used to study the composite's thermal behaviour.Composites are more thermally stable than raw epoxy.Fourier Transform Infrared Spectroscopy and Scanning electron microscopy analyses were used to characterize the composites.

关键词： Banana Pseudostem fibre Al_(2)O_(3) epoxy Characterization Mechanical properties

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Recent progress on thermal conductivity of graphene filled epoxy composites

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Nano Materials Science 2022年第3期4卷 205-219页

作者： Ruicong Lv Yanjuan Ren Haichang Guo Shulin Bai School of Materials Science and Engineering HEDPS/Center for Applied Physics and TechnologyKey Laboratory of Polymer Chemistry and Physics of Ministry of EducationPeking UniversityBeijing100871China

With the rapid development of the electronic industry, the requirements for packaging materials with high thermal conductivity(TC) are getting higher and higher. epoxy is widely used as package material for electronic package applications. But it’s intrinsic TC can’t meets the increasing demands. Adding high TC graphene into epoxy matrix is a proper way to reinforce epoxy composites. This review focuses on the filler modification,preparation process and thermal properties of graphene-filled epoxy resin composites. Different ways of covalent and non-covalent modification methods are discussed. The various kinds of graphene coating layer are also summarized. Then we analysis the hybrid filler system in epoxy composite. We hope this review will provide guidance for the development and application of graphene-filled epoxy resin composites.

关键词： Graphene epoxy Composites Thermal conductivity

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Investigation on forward and backward transfer process during carbon fiber/epoxy composites dry-sliding against iron alloy

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Science China(Technological Sciences) 2022年第11期65卷 2564-2572页

作者： LU LongSheng LI ZeHong FANG HeZhengZi XIE YingXi WANG WenTao School of Mechanical&Automotive Engineering South China University of TechnologyGuangzhou 510641China

Carbon fiber reinforced polymer(CFRP)composites with high load-bearing capacity are currently ideal materials in tribological load systems.One of the unique features during the friction process of CFRP/metal is the in-situ formation of an ultrathin and uniform transfer film on the metal surface,and the related initial/transfer mechanism is very important but still unclear.Recent studies mainly focus on the one-way transfer process of CFRP to the metal surface,that is,forward transfer;whereas another easily overlooked issue is that the metal material also transfers backward to the CFRP surface.Herein,we firstly prepared carbon fiber/epoxy resin composites(CF/EP)by the hot-pressing method and then carried out friction tests with iron alloy as the control material.The underlying mechanism of the forward/backward transfer process is revealed by controlling the morphological evolution and iron content of the transfer film on worn CF/EP.According to the variation law of friction coefficient with time,the interfacial friction is divided into three different stages,among which the behaviours of“micro-convex contact”and“epoxy exfoliation”occur throughout the whole procedure.We believe this work could provide a meaningful reference for studying the friction behaviour and mechanism,especially the forward and backward transfer between composites/metals,and further broaden its emerging applications in future energy,aerospace and rail transportation.

关键词： carbon fiber epoxy composite transfer film friction mechanism

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Pyrolysis Mechanism of a Cyclotriphosphazene-Based Flame-Retardant epoxy Resin by ReaxFF Molecular Dynamics

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中国炼油与石油化工:英文版 2023年第3期25卷 136-152页

作者： Jiang Shuaijun Meng Weifeng Wan Yongqing Qin Weihua Liu Xiaoqing Lan Yanhua School of Environment and Safety Engineering North University of ChinaTaiyuan 030051China

Cyclotriphosphazene derivatives can effectively improve the flame retardancy and fire safety of epoxy resins(EPs)via their influence on the pyrolysis process.In this work,the effects of hexa(5-methyl-2-pyridinoxyl)cyclotriphosphazene(HMPOP)incorporation on the initial pyrolysis of an EP at 500–3500 K were studied using the ReaxFF method.The pyrolysis fragments,initial reaction pathways,and main products were identified for the EP and EP/HMPOP composites.The activation energies were derived by fitting the weight percentage curves for solid species during the pyrolysis reactions and the obtained values were in good agreement with experimental data.The initial EP pyrolysis reactions included four major decomposition modes,which primarily involved the cleavage of C–O and C–N bonds.The main pyrolysis products were H_(2)O,CO,C_(2)H_(4),and CH_(2)O.HMPOP bonded with the oxygen-containing fragments to form larger molecular fragments and reduced the amounts of C_(0)–C_(4) products,especially that of the harmful gas CH_(2)O.Thus,HMPOP promoted the formation of carbon clusters and reduced the generation of combustible gases,ultimately decreasing the capacity for fire propagation.

关键词： epoxy cyclotriphosphazene ReaxFF pyrolysis flame retardancy

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Influence of graphene nanoplatelets on mechanical properties and adhesive wear performance of epoxy-based composites

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Friction 2021年第4期9卷 856-875页

作者： K.Y.EAYAL AWWAD B.F.YOUSIF Khosro FALLAHNEZHAD Khalid SALEH Xuesen ZENG Faculty of Health Engineering and SciencesUniversity of Southern QueenslandToowoombaQLDAustralia Centre for Future Materials University of Southern QueenslandToowoombaQLDAustralia School of Mechanical and Mining Engineering University of QueenslandBrisbaneQLDAustralia

epoxy resin is one of the most widely used thermoset polymers in high-performance composite materials for lightweight applications.However,epoxy has a high coefficient of friction,which limits its tribological applications.In this study,the effect was investigated of different weight fractions of solid lubricant graphene nanoplatelets(GNPs),ranging from 0 to 4.5 wt%,on mechanical and adhesive wear performance of epoxy.Adhesive wear tests covered mild and severe wear regimes.The correlation of tribological and mechanical properties was studied as well.Scanning electron microscopy(SEM)was used to observe the failure mechanisms for both tribological and mechanical samples after each test.The results revealed that the addition of GNPs to the epoxy improved its stiffness and hardness but reduced its fracture strength and toughness.Adhesive wear performance exhibited high efficiency with GNP additions and showed reductions in the specific wear rate,the coefficient of friction,and the induced interface temperature by 76%,37%,and 22%,respectively.A fatigue wear mechanism was predominant as the applied load increased.Most importantly,severe wear signs occurred when the interface temperature reached the heat distortion temperature of the epoxy.The tribological,and mechanical properties showed only a weak correlation to each other.The addition of GNPs to epoxy by less than 4.5 wt%was highly efficient to improve the wear performance while maintaining the fracture strength and toughness.Fourier transform infrared spectroscopy(FTIR)analysis shows no chemical interaction between the epoxy matrix with GNPs,which implies its physical interaction.

关键词： graphene nanoplatelets epoxy adhesive wear solid lubricants

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An effective and green H2O2/H2O/O3 oxidation method for carbon nanotube to reinforce epoxy resin

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Journal of Materials Science & Technology 2020年第5期40卷 24-30页

作者： Qi Wang Wen Shi Bo Zhu Dang Sheng Su School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China Shenyang National Laboratory for Materials Science Shenyang 110016China Jiangsu Gunuo New Materials Technology Go. Ltd.Yancheng 224051China

Facile green oxidation methods are always desired to functionalize carbon nanotubes(CNTs)in the production of advanced CNT/epoxy composites.In the present work,an optimized H2O2/H2O/O3 oxidation method was developed,and performances of the H2O2/H2O/O3 oxidized CNT in epoxy matrix were tested and compared with that of the H2O/O3 oxidized CNT and the most commonly used concentrated HNO3 oxidized CNT.The physical and chemical characteristics of the obtained oxidized CNTs were systematically characterized via transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and Raman.Mechanical performances of the obtained composites were explored by tensile tests,impact tests,dynamic mechanical analysis(DMA)and fracture toughness tests.It was found that the H2O2/H2O/O3 oxidized CNT exhibited all-around overwhelming advantages over the concentrated HNO3 oxidized CNT on reinforcing the epoxy matrix,while the H2O/O3 oxidized CNT only improved the material strength.Reinforcing mechanisms for the different methods oxidized CNTs were studied and compared.The optimized H2O2/H2O/O3 oxidation method makes scaled production possible,avoids environment pollutions,and holds great potentials to replace the most commonly used concentrated HNO3 oxidation method to oxidize CNT during the preparation of the advanced CNT/epoxy composite.

关键词： Green oxidation method Carbon nanotube epoxy composite Mechanical properties Interfacial interaction

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Formulating Novel Halogen-Free Synergistic Flame Retardant epoxy Resins for Vacuum Assisted Resin Infusion Composites

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Journal of Donghua University(English Edition) 2022年第2期39卷 120-127页

作者：王明魏毅邱夷平 College of Textiles Donghua UniversityShanghai 201620China Center for Civil Aviation Composites Donghua UniversityShanghai 201620China

The most common process to manufacture advanced composites is the costly autoclave.One of the out-of-autoclave alternatives is the low-cost vacuum assisted resin infusion(VARI)which produces quality parts with less pollution.epoxy resin is a widely used composite matrix resin,but its high flammability limits its use as interior composite parts for vehicles.The usual flame retardant for epoxy involves halogen,which is effective but has high smoke toxicity.As a result,halogen-free flame retardant epoxy resin systems become dominant.In this paper,phosphorus flame retardant was combined with benzoxazine(BOZ)to produce synergistic effect and achieve satisfactory flame retardance,as well as mechanical improvement for the epoxy resin.Differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),thermal gravitational analysis(TGA),the cone calorimeter(CC),and limiting oxygen index(LOI)were used to characterize the resins.The results showed significant improvement on the flame retardance of the synergistically modified resins.Specifically,the carbon residue increased by 113.6%,and the char thickness increased by 6 to 7 times,compared to those of the flammable benchmark resin.The LOI reached 33 and passed the UL94 V-0 vertical burn rating.The modified resins also exhibited adequate stability and viscosity suitable for VARI processes.

关键词： synergistic flame retardant epoxy benzoxazine(BOZ) vacuum assisted resin infusion(VARI) composite

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