高性能酚醛树脂/石墨双极板导电复合材料的制备

以酚醛树脂与石墨粉料为原料,通过热模压成形得到一种质子交换膜燃料电池双极板材料.研究了酚醛树脂含量、石墨粒径和固化温度对复合材料导电性能与弯曲强度的影响.结果表明随酚醛树脂含量的增加,导电性能降低,强度升高;随石墨粒径的增大,复合材料的导电性能和弯曲强度呈现先增大后减小的趋势;随固化温度的增加,导电性能出现明显波动,而弯曲强度呈先增大后减小的趋势;酚醛树脂质量分数为15%,石墨颗粒粒径为105 μm,固化温度为240℃时,导电复合材料的电导率和弯曲强度可达142 S/cm,61.6 MPa.     

酚醛树脂含量对R/C复合材料性能的影响

以石墨与酚醛树脂粉料为原料,通过热模压成形得到一种R/C复合材料。研究了质量分数为20%～30%酚醛树脂对复合材料导电、力学以及阻气性能的影响;并利用SEM分析了不同酚醛树脂含量复合材料的断口和表面形貌。结果表明,随酚醛树脂含量的增加,能够使复合材料的抗弯强度、冲击强度和电阻率明显提高,而密度先上升后下降。试验中,当酚醛树脂质量分数为22.5%时,R/C复合材料的阻气性最好,此时抗弯强度、冲击强度、电阻率和密度分别为45.5MPa,8.9J/cm2,169.3×10-6Ω·m和1.93g/cm3,其值达到或超过国内外同类研究水平。     

聚甲基丙烯酸甲脂/多壁碳纳米管复合材料的制备与电性能

对碳纳米管进行表面改性,改变纳米碳管表面性质。采用溶液共混法制备了多壁碳纳米管/聚甲基丙烯酸甲酯复合材料,采用扫描电镜(SEM)、透射电镜(TEM)观察了复合材料的微观结构,测试了复合材料的物理机械性能及导电性能。结果表明:采用溶液共混并用超声波分散的方法使多壁碳纳米管(MWNTs)分散在PMMA基体中,随着MWNTs含量的增加,复合材料的电导率呈先上升后持平的趋势。并发现MWNTs质量分数为3%时,其拉伸强度为84 MPa;MWNTs质量分数为4%时,其冲击强度为24.19 kJ/m2。     

环氧树脂/石墨烯复合材料的制备及其性能

为提高环氧树脂的导电性能和电磁屏蔽性能,将石墨烯作为导电填料添加到环氧树脂中制备了环氧树脂/石墨烯复合材料,并研究了石墨烯含量对复合材料力学性能及微观形貌的影响。结果表明：添加石墨烯使复合材料的电导率和电磁屏蔽效率显著提高。石墨烯含量为10.0%(w)时,复合材料的电导率和电磁屏蔽效率分别为1.34×10^-3 S/m,2.95 dB;石墨烯含量为7.5%(w)时,复合材料的冲击强度为1.67 kJ/m²,较纯环氧树脂提高了50%。     

聚苯乙烯/纳米TiO2/SEBS三元复合材料的制备及性能研究

采用熔融共混法制备了聚苯乙烯/纳米二氧化钛/氢化苯乙烯乙烯丁二烯苯乙烯共聚物（PS/纳米TiO2/SEBS）三元复合材料。研究了SEBS和纳米TiO2用量对复合材料力学性能、扭矩以及热性能的影响。利用扫描电子显微镜对复合材料冲击断面的微观形貌进行了研究。结果表明,PS/纳米TiO2/SEBS复合材料的冲击强度随SEBS含量的增加逐渐增大,拉伸强度随SEBS含量的增加逐渐减小。当PS与纳米TiO2的质量比为97/3、SEBS的用量为8份(质量份,下同)时,复合材料的综合力学性能最佳,其冲击强度为5.626 kJ/m2,拉伸强度为25.623 MPa;加入纳米TiO2和SEBS都使复合材料的热性能得到了提高;复合材料的最大扭矩与PS相比下降了17 N·m,平衡扭矩均为7 N·m;SEBS以颗粒状镶嵌到基质中,断口形貌为典型的韧性断裂。     

增韧聚丙烯导电纳米复合材料研究

以碳纳米管(CNT)作为导电组分,以乙烯-辛烯共聚物(POE)作为增韧剂,通过熔融复合制备PP/POE/CNT三组分纳米复合材料,研究微观结构与电导率和缺口冲击强度的关系.实验结果表明:PP/CNT两组分纳米复合材料由电绝缘体向丰导体的逾渗转变发生在CNT质量含量为2～3%时.POE的加入延迟了纳米复合材料的逾渗转变,这说明POE的存在延缓了纳米复合材料中导电通路的形成.重要的是,30%POE赋予了导电纳米复合材料超高韧性.     

环氧树脂/碳纳米管复合材料的性能研究

采用溶液混合法制备了环氧树脂/碳纳米管复合材料,探讨了碳纳米管的含量对复合材料拉伸和导电性能的影响。结果表明:随着碳纳米管含量的增加,复合材料的拉伸强度、杨氏模量和断裂伸长率均先提高后降低;当其质量分数为0.6%时,复合材料拉伸性能达到最优值且比纯环氧树脂分别提高了82.5%,40.2%和43.8%。复合材料的电导率呈现典型的渗阈行为,当碳纳米管的质量分数为1.8%时,复合材料电导率为1.31×10-5S/m,达到了半导体级别。     

3D打印炭黑/水性聚氨酯导电复合材料的制备及性能

采用硅烷偶联剂KH550对炭黑（CB）进行共价键功能化改性,并通过FTIR、DLS和SEM对改性前后的炭黑进行考察。结果表明经过KH550改性得到的炭黑,粒径约为620nm,且分散均匀。通过溶液共混法和流延浇铸法制备了CB/WPU与KH550/CB/WPU导电复合材料。研究对比发现,由于KH550/CB在WPU基体中分散性更好,使导电粒子之间接触更加紧密。当添加量为3%时,其电导率为1.79×10-3 S/m,较CB/WPU复合材料增加了10倍;力学测试显示含量为2%时,其拉伸强度较CB/WPU复合材料增加了175%。并在此基础上利用直写式3D打印,探讨不同的填充图案和填充率对KH550/CB/WPU复合材料导电性能的影响。结果显示选择线型填充、填充率为80%时,导电性能较好,其电导率达到2.66×10-3 S/m。     

酚醛树脂/镀银碳纤维导热复合材料的制备与性能

采用化学镀的方法在碳纤维(CF)上镀一层银膜,然后采用搅拌混合的方法制备了酚醛树脂/镀银碳纤维(Ag-CF)导热复合材料,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能量色散光谱仪(EDS)等方法对其结构和性能进行表征。结果表明,大量的银粒子均匀分布在CF表面;酚醛树脂/Ag-CF导热复合材料的导热系数、冲击强度和拉伸强度随着Ag-CF含量的增加而逐渐增加;Ag-CF的含量为7.0 %时,酚醛树脂/Ag-CF导热复合材料的综合性能最优,此时其导热系数为1.25 W/(m·K),冲击强度和弯曲强度分别为66.7 kJ/m2和139.2 MPa;残炭率为30 %时,添加量为7.0 %的复合材料对应温度为 500 ℃,高于纯酚醛树脂的 450 ℃。     

具有隔离结构的聚苯硫醚/石墨烯纳米片 复合材料的制备及电磁屏蔽性能研究

导电填料石墨烯纳米片（GNPs）通过高速混合包覆于聚苯硫醚（PPS）树脂基体颗粒表面,再通过热压成型制备出具有完善隔离结构的PPS/GNPs复合材料。采用光学显微镜、扫描电子显微镜、电导率测试、电磁屏蔽性能测试对复合材料导电网络形貌、电性能和电磁屏蔽性能进行表征。结果表明,复合材料具有完善的隔离结构导电网络;隔离结构复合材料具备优异的电导率和电磁屏蔽效能（EMI SE）,当GNPs含量为3.0 %（质量分数,下同）时,复合材料的电导率和EMI SE分别为25.6 S/m和41.0 dB。     

二维晶体Ti3C2Tx MXene发射与屏蔽电磁波的研究进展

MXene是一种新型二维材料,通过剥离层状陶瓷MAX相而制备.Ti3C2Tx MXene 是第一种制备的MXene,也是应用最广泛的MXene.Ti3C2Tx MXene具有良好亲水性,可以分散在水中制备成薄膜.同时具有良好导电性,具有叠层结构,电磁波可以在材料内部的界面多次反射.因为独特的性能与结构,MXene可以作...     

Toughening of vinyl ester resins by two-dimensional MXene nanosheets

Two-dimensional nanosheets are highly effective tougheners for vinyl ester resins. The toughening effect is related to the high specific surface area and unique two-dimensional planar structure of the nanosheets. In this study, a coupling agent γ-(2,3-epoxypropoxy) propytrimethoxysilane (Kh-560) was used to modify MXene nanosheets (M-MXene) for use in toughening vinyl ester resin. The mechanical properties, including the tensile strength, flexural strength, Young’s modulus and elongation, of neat vinyl ester resin and vinyl ester resin modified with MXene and M-MXene were investigated. The results showed that modification significantly improved the mechanical properties of the vinyl ester resin. The tensile and flexural strengths of the MXene-nanosheet-modified vinyl ester resin were 27.20% and 25.32% higher, respectively, than those of the neat vinyl ester resin. The coupling agent improved the interfacial compatibility between the MXene nanosheets and vinyl ester resin, which resulted in the tensile and flexural strengths of the M-MXene-nanosheet-modified vinyl ester resin being 52.57% and 54.60% higher, respectively, than those of the neat vinyl ester resin for a loading quantity of nanosheets of only 0.04 wt %, which is economically viable. The main mechanisms by which the nanosheets toughen the resin are crack deflection and crack pinning.     

Conductive and antibacterial scaffold with rapid crimping property for application prospect in repair of peripheral nerve injury

Peripheral nerve injury (PNI) is a severe clinical disease leading to the loss of sensory and motor function and even lifelong disability of patients. Nerve scaffolds with conductive materials are beneficial to PNI repair and regeneration through the recovery of electrical signals transmission and regulation of nerve cell membrane function. In this study, composite poly(lactide-co-glycolide) (PLGA)/Ti3C2Tx (MXene) membranes with different content of MXene were fabricated by electrospinning, and these fibrous membranes showed favorable mechanical property for supporting nerve regeneration. With loaded MXene, the electrospun membranes exhibited good antibacterial property that the antimicrobial rate was as high as 80%, which is conducive to the prevention of wound inflammation after stent implantation. The loaded MXene also improved the hydrophilicity and conductivity of the electrospun composite membranes, which provided good biocompatibility for cell growth. Interestingly, treating in 75% ethanol solution made fabricated PLGA/MXene membranes rapidly crimp into stable nerve conduits for implanted application. These fabricated PLGA/MXene membranes showed good potential for nerve repair and have a good prospect for nerve conduit application.     

Mechanical and electrical properties of MoSi2–RSiC composites via a combination of phenolic resin infiltration–pyrolysis and MoSi2–Si–Ti alloy-activated melting infiltration composite processes

A three-dimensional interpenetrated network structure composite was designed and prepared via a combination of phenolic resin infiltration-pyrolysis and MoSi₂–Si–Ti alloy-activated melting infiltration processes to effectively merge the desirable properties of MoSi₂ and RSiC. Influence of infiltration temperature on the microstructure, mechanical and electrical properties of the composites was examined. Almost dense MoSi₂–RSiC composites with the designed structure were obtained at 1900°C. Formation of the gradient interface modified the interface combination and enhanced the mechanical and electrical properties of the composite. Flexural strength of the composites reached approximately 114.262?MPa (room temperature) and 128.392?MPa (1400°C), respectively, indicating corresponding increases of 37.08 and 35.69% compared with the RSiC matrix. Volume resistivity decreased to 57.63?mΩ?cm, nearly five orders of magnitude lower than that of RSiC. Influence of the interpenetrated network structure and interface combination on the electrical conductivity behaviour of the composites was discussed via a modified mixture rule.     

Synthesis,characterization and antifungal property of Ti3C2Tx MXene nanosheets

Although the antibacterial properties of MXene nanosheets containing Ti₃C₂T_x are known, their antifungal properties have not been well studied. Herein, we present for the first time a report on the antifungal properties of Ti₃C₂T_x MXene. The Ti₃C₂T_x MXene was obtained by first exfoliating MAX phase of Ti₃AlC₂ with concentrated hydrofluoric acid, then the Ti₃C₂T_x was intercalated and deliminated by ethanol treatment and ultrasonication process. The delaminated Ti₃C₂T_x MXene nanosheets (d-Ti₃C₂Tx) were characterized using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), X-ray diffraction spectroscopy (XRD), and Raman spectroscopy. It was found that Ti₃C₂T_x MXene was characterized by lamellar structure alternating with layers of Ti, Al and C. The EDX results revealed that the delaminated Ti₃C₂T_x MXene nanosheets were composed of Ti, C, Si, O, F, and a trace amount of Al. The XRD and Raman spectra further indicated the elimination of Al and the formation of two-dimensional Ti₃C₂T_x MXene nanosheets. The antifungal activity of the delaminated Ti₃C₂T_x MXene was determined against Trichoderma reesei using the modified agar disc method. Observation using inverted phase contrastmicroscopy revealed inhibited fungus growth with the absence of hyphae around the discs treated wtih MXene. The surrounding of the control groups without an inclusion of MXene was found with large number of hyphae and spores. In addition, the spores of the fungi treated with the samples containing d-Ti₃C₂T_x MXene nanosheets did not germinate even after 11 days of culture. The results demonstrated disruption to the hemispheric structural formation of fungi colony, inhibition of hyphae growth and cell damage for fungi grown on the d-Ti₃C₂T_x MXene nanosheets. These new findings suggest that d-Ti₃C₂T_x MXene nanosheets developed in this work could be a promising anti-fungi material.     

MXene Reinforced PAA/PEDOT:PSS/MXene Conductive Hydrogel for Highly Sensitive Strain Sensors

Conductive hydrogel has a vital application prospect in flexible electronic fields such as electronic skin and force sensors. Developing conductive hydrogel with significant toughness and high sensitivity is urgently needed for application research. In this work, a strong and sensitive strain sensor based on conductive hydrogel is demonstrated by introducing MXene (Ti3C2Tx) into the micelle crosslinked polyacrylic acid (PAA)/poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) hydrogel network. The functional polymer micelle crosslinkers can dissipate external stress by deformation, endowing the hydrogel with high strength. The combination of MXene both improves the polymer network structure and the conductive pathways, further enhancing the mechanical properties and sensing performance. Resultantly, the flexible strain sensor base on PAA/PEDOT:PSS/MXene conductive hydrogel exhibits excellent sensing performance with a high gauge factor of 20.86, a large strain detection range of 1000%, as well as good adhesion on different interfaces. Thus, it can be used to monitor various movements of the human body and identify all kinds of handwriting, showing great potential into wearable electronics.     

Differences in physico-mechanical behaviors of resol(e) and novolac type phenolic resin based composite bipolar plate for proton exchange membrane (PEM) fuel cell

Composite bipolar plates for Proton Exchange Membrane Fuel Cell (PEMFC) are prepared by compression molding technique using polymer as binder and graphite as electric filler material with some other reinforcements. Study on the effect of resole and novolac type phenolic resin on the properties of composite bipolar plate, such as bulk density, porosity, bulk conductivity, hardness, flexural strength, etc. shows that both of the resin shows different physico-mechanical properties. Moreover, single cell performance analysis also shows variation for resole and novolac based composites. A novel concept of triple continuous structure to provide graphite polymer blends with high electrical conductivity, high shore hardness, high flexural strength, less porosity and low density has been proposed and study on the effect of different types of phenolic resin on the properties and performance of bipolar plate reveals that novolac type powdered phenolic resin gives better mechanical properties than resole type phenolic resin. However, resole type phenolic resin compound has slightly higher electrical conductivity due to more number of polar -OH group presents on its cured form. But due to the less porosity and higher mechanical strength, bipolar plates with novolac type phenolic resin gives better performance in I-V analysis than bipolar plates with resole type phenolic resin.     

有机硅改性酚醛树脂的研究

采用有机硅改性剂通过共混法改性了热固性酚醛树脂。通过红外,热重分析以及力学性能测试研究了有机硅用量对酚醛树脂热性能和力学性能的影响。结果表明:加入的有机硅改性剂的质量分数为25%时,酚醛树脂的主体结构分解温度提高了36℃,分解速率降低了21%,最终残炭率增加了10.05%,并且拉伸强度由49.68 MPa提高到77.46 MPa,冲击强度由8.3 kJ/m2提高到11.89 kJ/m2。     

Effects of phenolic resin contents on microstructures and properties of c/sic-diamond composites

In this paper, C/SiC-diamond composites were obtained by chemical vapor infiltration (CVI) and reactive melt infiltration (RMI), and the effects of phenolic resin contents on the microstructures and properties of as-obtained C/SiC-diamond composites were studied. The results suggested a significant influence of phenolic resin contents on the pore structure of the composites before reactive melt infiltration (RMI), as well as phase composition and density of the matrix after RMI. The mechanical properties of composites were shown to correlate with the threshold effect of phenolic resin. Sample R5 prepared with high phenolic resin contents displayed significantly declined mechanical properties. On the other hand, adjustment of the phenolic resin content yielded samples with maximum room temperature thermal conductivity reaching 14.75 W/(m·K). The theoretical thermal conductivity of the composites calculated by the Hasselman-Johnson (H-J) theoretical model was estimated to 24.52 W/(m·K). Overall, the increase in phenolic resin content led to unreacted diamond-C regions and the formation of substantial porosity. These features reduced the thermal conductivity of the resulting C/SiC-diamond composites.