Investigation of covalently grafted polyacrylate chains onto graphene oxide for epoxy composites with reinforced mechanical performance

To enhance the dispersion and interfacial interaction of graphene–epoxy matrix, polyacrylate chains grafted graphene oxide (PA-GO) was manufactured with A-174 functionalized GO (A-GO), methyl acrylate, and glycidyl methacrylate via free-radical random copolymerization technique. Fourier transform infrared, thermogravimetric analysis, X-ray photoelectron spectrum, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, and nuclear magnetic resonance were performed to investigate the structure of A-GO and PA-GO. Then, the PA-GO was incorporated into epoxy resin via in situ solution intercalation dispersion method in order to form an interpenetrating network structure with epoxy resin. Field emission scanning electron microscope results indicate that the PA-GO exhibits excellent dispersion and interfacial compatibility in the epoxy matrix. In compared with pure epoxy, the tensile strength and impact strength of the epoxy composite with 1 wt % PA-GO were shifted from 62.78 ± 2.54 to 70.68 ± 2.02 MPa (about 12.6%) and 3.55 ± 0.41 to 4.98 ± 0.33 kJ m⁻² (about 40.3%), respectively. Moreover, increased storage modulus is also observed in the dynamic mechanical analysis measurements compared with that of neat epoxy resin. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47842.     

Ionic liquid modified graphene oxide for enhanced flame retardancy and mechanical properties of epoxy resin

In this work, to improve its dispersion and flame retardancy, graphene oxide (GO) was functionalized by silane coupling agent KH550 and 1-butyl-3-methylimidazole hexafluorophosphate (PF₆-ILs), and characteristics of the PF₆-ILs@GO was obtained by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Then, the synergistic flame retardant of GO or PF₆-ILs@GO and melamine pyrophosphate (MPP) were applied for epoxy resin (EP) materials. Specifically, the limiting oxygen index (LOI) value of EP with 0.1 wt% PF₆-ILs@GO was increased to 29.2% from 27.5% of EP/MPP composites, and the UL-94 test reached the V-0 rating. The CCT results showed that the total heat release (THR) and total smoke release (TSP) of EP/MPP/PF₆-ILs@GO composites were significantly 24.4% and 53.4% lower than that of EP/MPP composites. Besides, the thermal behavior investigated by TGA indicated that the char-forming effect of GO and PF₆-ILs@GO was great, the residual char of EP/MPP/PF₆-ILs@GO composites was as high as 19.5% at 700°C, and its thermal stability was higher than that of EP/MPP composites. On the other hand, the tensile strength of EP/MPP/GO and EP/MPP/PF₆-ILs@GO composites were increased by 15.6% and 28.3% compared with EP/MPP composites. According to SEM analysis, the EP/MPP/GO composites formed a good protective char layer, which can effectively improve flame retardancy of EP. This research represents a new method of flame retardant modified GO to improve the flame retardancy and mechanical properties of polymers.     

羟基磷灰石增强环氧树脂结构胶的力学性能研究

采用羟基磷灰石(HA)对环氧树脂结构胶进行改性。对改性后结构胶的力学性能进行测试。实验表明:随着HA的掺量增加,环氧结构胶的压缩强度、冲击强度、粘钢剪切强度提高、拉伸强度略有降低;当羟基磷灰石的掺量为5％时。环氧树脂结构胶的压缩强度、冲击强度分别为92MPa、6．8kJ／m2,比纯环氧树脂基体提高28％和70％;当羟基磷灰石的掺量为7％时,环氧树脂结构胶的粘钢剪切强度为26．4MPa．比纯环氧树脂基体提高55％,羟基磷灰石对环氧树脂有较好的增强增韧作用。     

Viscoelastic and mechanical characterization of graphene decorated with graphene quantum dots reinforced epoxy composites

The article explores viscoelastic and mechanical property analysis of graphene decorated with graphene quantum dots (GDGQD) reinforced epoxy composite. Tensile, nanoindentation, and nano-dynamic mechanical analysis (DMA) tests were conducted on the composite with 0 to 1 wt% filler variation (an interval of 0.25 wt% maintained). The hardness and elastic modulus for two different loading conditions under a frequency range of 10 to 250 Hz were performed. The viscoelastic properties described through loss tangent and storage modulus graphically and the various factors such as modulus and depth of penetration were influenced by force frequency and mobility of the molecular chain. The results revealed the role of GDGQDs as filler material for enhancing the nanomechanical and tensile properties of the epoxy matrix. The differences in the properties can be ascribed to the filler interfacial bonding with the polymer matrix at the molecular level. The macro-level properties like tensile properties following the same trend as that of the micro-level properties like nano-indentation and nano-DMA results. Further, with the GDGQD aspect ratio, and assuming three-dimensionally filled randomly orientation of filler, the Halpin-Tsai model was satisfied with the experimental tensile modulus values.     

Carbon fibre reinforced epoxy composites

Carbon fibre reinforced epoxy composites were fabricated from the matrix resin diglycidyl ether of bisphenol-A and novel tetrafunctional epoxy resins N,N,N′,N′-tetraglycidyl-2,2-bis[4-(4-aminophenoxy)phenyl]propane and N,N,N′N′-tetraglycidyl-1,1 ′-bis[4-(4-aminophenoxy)phenyl]cyclohexane using diaminodiphenyl methane as curing agent. Mechanical properties and chemical resistance of the composites were determined. Significant improvements in the mechanical properties were observed by adding epoxy fortifier to the resin-curing agent mixtures before fabrication of composites.     

氧化石墨烯改性环氧树脂涂料的制备及防腐性能

环氧树脂在溶剂蒸发过程中容易产生微孔,影响其防腐蚀性能。为了提高其对腐蚀介质的阻碍能力,本文采用密闭氧化法制备氧化石墨烯,再利用湿式转移法将氧化石墨烯水溶液分散在环氧树脂中,制备氧化石墨烯/环氧树脂防腐涂料。通过红外光谱（FTIR）、X射线衍射（XRD）和拉曼光谱（Raman）分析氧化石墨烯的结构变化,利用开路电位测试（OCP）、水接触角、腐蚀形貌和气体透过率分析氧化石墨烯/环氧树脂涂料的防腐性能。结果表明,氧化石墨烯/环氧树脂（GO/EP）涂料的开路电位和水接触角分别为0.181V和86.12°,与纯环氧树脂涂料相比,分别提高了0.066V和10.5°;当GO/EP浸泡在3.5%NaCl溶液中腐蚀20天后,表面仅产生了粗糙化,涂层稳定性好,屏障性能强;与EP涂层相比,GO/EP涂层的O₂和H₂O渗透率分别降低了51.2%和65.5%。     

改性空心玻璃微珠/环氧树脂复合材料力学性能研究

采用偶联剂对玻璃微珠表面进行改性处理,借助超声波振动,使改性空心玻璃微珠在环氧树脂中均匀、稳定分散,增强了玻璃微珠与环氧树脂之间的相容并探讨了改性空心玻璃微珠对环氧树脂力学性能的影响。结果表明,复合材料中改性空心玻璃微珠添加质量分数为3%时,其拉伸强度达到最大值68.54 MPa,与空白样相比提高了20.3%;冲击强度达到最大值24.42 kJ/m2,比纯环氧树脂提高了166%;KIC(断裂韧性)达到最大值2.338 MPa/m2,是空白试样的2.27倍,增韧效果较为明显。     

软质PVC环/氧树脂共混物性能的研究

考察了PVC/环氧树脂(E51)共混物(未固化与固化)的力学性能和加工性能,采用电子扫描显微镜观察了粒子在基体中的分散情况。结果表明:①在试验条件下,E51质量分数为5%(以PVC/E51质量为100%计,下同)时,试样的力学性能较好。②当E51质量分数为10%时,共混物的最大转矩最低;当E51质量分数为13%时,共混物的平衡转矩最低。③经过固化的试样的力学性能优于未固化的试样。④E51的加入能够改善试样的相容性与粒子的分散效果。     

Incorporation of hyperbranched polyamide‐functionalized graphene oxide into epoxy for improving interfacial and mechanical properties

The incorporation of hyperbranched polyamide‐functionalized graphene oxide (HPA‐GO) into epoxy was proposed to improve the interfacial and mechanical properties. Benefiting from improved dispersion and strengthened interfacial interaction, epoxy composites with HPA‐GO showed significant improvements in mechanical and thermomechanical properties at low GO loading. The interaction at the HPA‐GO/epoxy interface was investigated to confirm the occurrence of chemical bonding. Strong interfacial bonding improved the stress transfer and distribution of HPA‐GO/epoxy interface. Accordingly, the overall strength of epoxy composites was effectively improved on account of the uniform dispersion of HPA‐GO and interfacial chemical interaction between HPA‐GO and epoxy. Compared with neat epoxy resin, the inclusion of 0.10 wt% HPA‐GO led to 310.5 and 37.2% increase in impact strength and tensile strength, respectively. © 2019 Society of Chemical Industry     

纤维增强环氧树脂基复合材料的研究进展

综述了纤维增强环氧树脂基复合材料的应用及研究进展,其中包括玻璃纤维(GF)增强、碳纤维(CF)增强,芳纶纤维,混杂纤维及植物纤维增强等。     

Preparation and dynamic mechanical properties of polyurethane‐modified epoxy composites filled with functionalized fly ash particulates

Fly ash (FA) is a porous ceramic, which has proved to have some favorable functions. In this article, we have prepared a series of fly ash filled composites, where the polyurethane‐(PU) modified epoxy (EP) was acted as the matrix. With the purpose of characterizing the effect of the content of PU in the matrices and the surface‐treatment (ST) of fly ash particulates on the dynamic mechanical properties of composites, Fourier transform infrared spectral analysis (FTIR), microstructure observation, impact property test as well as dynamic mechanical analysis (DMA) were systematically investigated. With FTIR test, it can be found that the chemical reactions occur, and new chemical structures are formed between EP and PU, and the functionalized groups existing on the surface of fly ash particulates can also be detected. In fractographs observation of composites, it can be seen that the silane coupling agent improves the interfacial bonding conditions between fly ash particulates and the matrix. Impact property test result reveals that PU improves the toughness of EP. Dynamic mechanical analysis of the composites is carried out from ?40 to 150°C using a tension‐compression mode. Results show that the composites, whose matrices are with 10 and 20 wt % PU, may possess better dynamic mechanical properties as compared with the other composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermal and mechanical properties of epoxy composites reinforced by a natural hydrophobic sand

If a low weight percentage of crude fine fillers can improve properties of polymer materials directly without complicated chemical treatment process involved, it will be significant for many industrial applications. Our previous study indicated that a kind of Cancun natural sand could be an effective filler material for polymer composites. In this current work, the epoxy composites reinforced by this kind of natural sand particles were prepared and thermal and mechanical properties of the composites containing up to 5 wt % of the sand particles were characterized. Results showed that the highest flexural strength appears in the epoxy composite containing 1 wt % sand particles. A damage model was used to interpret the flexural properties, which showed an acceptable agreement with the experimental results. The glass transition temperature, high temperature storage modulus, and dimensional stability of the sand/epoxy composites monotonically increased with the addition of the sand particles. The sand particle/epoxy composites also displayed a noticeable enhancement in thermal conductivity. Theoretical analysis showed that in addition to conduction, other heat transport mechanisms played roles in the improved heat transmission through the composites. As a natural porous micron-scale material, Cancun sand has the potential for applications in cost-effective composites with enhanced mechanical and thermal properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

介孔MCM-48粉体对环氧树脂性能影响

采用溶液共混法制备了介孔MCM-48粉改性环氧树脂复合材料,研究了MCM-48添加量对复合材料力学性能及介电性能的影响。结果表明,添加少量的MCM-48粉能够同时对环氧树脂起到增强增韧效果。复合材料1MHz下的介电常数及介电损耗均随MCM-48添加量的增加先降低后升高。当MCM-48的添加量为2%时,复合材料的综合性能最佳,弯曲强度为82.15 MPa,弯曲弹性模量为2.45 GPa,冲击强度为21.75 kJ/m2,分别比纯环氧树脂提高了27.36%、28.32%、136.59%。复合材料1MHz下的介电常数为3.55,介电损耗为0.028。该材料有望在微电子领域获得应用。     

Epoxy-functionalized polysiloxane reinforced epoxy resin for cryogenic application

The poor cryogenic mechanical properties of epoxy resins restrict their extensive application in cryogenic engineering fields. In this study, a newly synthesized epoxy-functionalized polysiloxane (PSE) is used to improve the cryogenic mechanical properties of bisphenol-F epoxy resin. The Fourier transform infrared spectra and nuclear magnetic resonance confirm the formation of epoxy-functionalized –Si–O–Si– molecular chain. The surface free energy test results show that the PSE has a better compatibility with epoxy resin. The mechanical test results show that the cryogenic tensile strength, failure strain, fracture toughness, and impact strength of epoxy resin is improved significantly by adding the suitable amounts of PSE. Compared to the neat epoxy resin, the maximum tensile strength (196.92 MPa, an improvement of 11.2%), failure strain (2.97%, an improvement of 33.8%), fracture toughness (3.05 MPa·m^1/2, an improvement of 30.7%) and impact strength (40.55 kJ m⁻², an improvement of 14.8%) at cryogenic temperature (90 K) is obtained by incorporating 10 wt % PSE into the neat epoxy resin. Moreover, the results also indicated that the tensile strength, Young's modulus, and fracture toughness of epoxy resin with the same PSE content at 90 K are higher than that at room temperature (RT). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46930.     

超支化环氧／双酚A环氧树脂杂化材料的性能研究

以超支化环氧树脂HTDE-2改性HTDE-2／双酚A型环氧树脂杂化材料的粘接性能和胶膜性能,探讨了HTDE-2的含量对杂化材料的剪切强度、剥离强度、铅笔硬度和耐磨性的影响。研究表明,随着超支化环氧树脂含量的增加,杂化材料的剪切强度、剥离强度、铅笔硬度和耐磨性先增加后下降,在HTDE-2用量为4％左右时具有最大值,综合性能最好。     

UV混杂固化硅氧烷改性水性PUA/邻甲酚醛环氧树脂的制备

制备了水性邻甲酚醛环氧树脂(o-CFER)和聚氨酯丙烯酸酯(PUA),研究了γ-缩水甘油醚氧丙基三甲氧基硅烷偶联剂KH560对紫外光-阳离子混杂固化PUA/o-CFER热固性树脂热性能的影响,并用动态力学谱仪和热重分析仪进行了表征。结果表明:PUA/o-CFER体系相容性很好,KH560用量占总质量的6%时,PUA/o-CFER热固性树脂的玻璃化转变温度达125.9℃;当KH560用量占总质量的8%时,PUA/o-CFER热固性树脂热降解所需活化能最高为41.41 kJ/mol,反应级数为1.54;固化后树脂涂膜的硬度达4 H,冲击强度达50 kg·cm,并具有良好的附着力。     

Fibre reinforced composites of multifunctional epoxy resins

Glass and carbon fibre reinforced epoxy composites were fabricated for N,N,N′,N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM) and its formulated systems with tri- and di-functional reactive epoxy diluents using 30% diaminodiphenyl sulphone (DDS) as a curing agent. The epoxy laminates were evaluated for their physical, chemical and mechanical properties [at room (26°C) and high (100°C) temperatures]. A marginal increase (<20%) in the mechanical properties of CFRP was found compared with GFRP laminates. Incorporation of epoxy diluents altered the mechanical properties of the composites significantly. The incorporation of triglycidyl-4-aminophenol diluent to TGDDM systems resulted in an improvement in mechanical properties of about 2–6%.     

The effects of graphene oxide addition on low velocity impact performance of aramid fiber reinforced epoxy composites

In this study, the impact of incorporating graphene oxide (GO) nanoparticles into the matrix of aramid fiber reinforced polymer (AFRP) composites was investigated. The GO nanoparticles were dispersed in the AFRP matrix at three different weight percentages: 0.1%, 0.3%, and 0.5%. The fabrication of the GO dispersed AFRP nanocomposites was achieved using the vacuum assisted resin infusion molding (VARIM) method, and the AFRP plates were cut using a water jet. The sectioned specimens of the fabricated nanocomposites were subjected to low velocity impact tests. The effects of introducing GO nanoparticles at different percentages were evaluated by analyzing the contact force, deflection, maximum absorbed energy versus time and contact force versus deflection curves. Finally, the key parameters of low velocity impact, including contact force, deflection, and maximum absorbed energy, were compared for the different fabricated AFRP nanocomposites. Based on the results, the AFRP composite with 0.3 wt.% of GO nanoparticles exhibited the best performance under low velocity impact loading conditions. However, the agglomeration of nanoparticles became a significant challenge when higher percentages of GO nanoparticles were added to the composite structure. The findings highlight the importance of determining the optimal percentage of nano materials for incorporation into composite structures.     

含有聚醚多胺环氧树脂网络的形态及力学性能

不同相对分子质量聚醚多胺与环氧树脂于６０℃混合后,加入固化剂二乙烯三胺,在８０℃＊ｈ,１２０℃＊４ｈ下固化,可制备含聚醚多胺的固化环氧树脂网络。     

Grafting multi-elements hybrid polymer brushes on graphene oxide for epoxy composite with excellent flame retardancy

In this paper, a silicon-oxygen coupling agent (MPS) with a double bond is hydrolyzed with graphene oxide (GO) to obtain MPS-GO. The polymerization of MPS-GO with the phosphorus-containing monomer (HEPO) is initiated with 2,2′-Azobis(2-methylpropionitrile) (AIBN) to obtain multi-elements hybrid polymer brushes grafting graphene oxide (HM-GO). As a flame retardant, different amounts of HM-GO are added to obtain EP composites. In this system, the properties of composite flame retardant obviously increase with the increasing of HM-GO. The limiting oxygen index (LOI) value of composites with 4 wt% addition of HM-GO is 31.0%, while the LOI value of EP-0 is only 23.9%. And the peak heat release rate (PHRR) value is reduced from 515.8 W g⁻¹ of pure epoxy resin to 376.9 W g⁻¹. In addition, with the increase of HM-GO addition, the T_g value, flexural strength and flexural modulus of EP composites are improved. Through calculation, it is proved that the rising of T_g was due to the increase of crosslink density of the system. The flame retardant performance and mechanical properties of the composite materials are steadily improved, indicating that such flame retardants are dispersed well in the epoxy resin. HM-GO is an efficient macromolecular modified graphene oxide halogen-free flame retardant, which can improve both flame retardant properties and mechanical properties.