MoS_(2)Lubricate‑Toughened MXene/ANF Composites for Multifunctional Electromagnetic Interference Shielding

The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.

Preparation and Performance of Short Carbon Fiber and Flake Graphene Reinforced Polycarbonate Composites: Effects of Different Tougheners

Different tougheners including methyl methacrylate-butadiene-styrene terpolymer (MBS, core-shell type), maleic anhydride (MAH) grafted ethylene-octene copolymer (EOM), and MAH grafted polyethylene wax (PEM) were investigated for toughening the polycarbonate (PC) composites reinforced by short carbon fiber (SCF) and flake graphene (FG). The effects of tougheners on the preparation, thermal conductivity and mechanical properties of PC composites were studied. Scanning electron microscopy was used for characterizing the impact fracture surfaces of the composites. The results showed that introducing tougheners into the carbon reinforced PC composites was beneficial to improving the processability, and PEM was more effective than EOM and MBS. Meanwhile, the through-thickness and the in-plan thermal conductivity decreased to some degree due to the isolated island effects of tougheners. Moreover, the brittle PC composites with high flexural stress could be easily toughened by tougheners. In contrast, PEM had better toughening function than EOM and MBS, and correspondingly, the stiffness of the composites was the lowest for the PEM toughened systems. The fractography revealed that dense and uniformly distributed carbon fillers dispersed in matrix PC and circular cavities coexisted in the composites. The naked fiber length gradually increased as the ductility of composite materials improved.

Bio-Based Hyperbranched Toughener From Tannic Acid and Its Enhanced Solvent-Free Epoxy Resin with High Performance

It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.

Influence of Different Tougheners on the Properties of PC/PBT Alloy

This paper focuses on the influence of glycidyl methacrylate functionalized polyolefin elastomer (SOG-03) on the properties of PC/PBT alloys, and also made a contrastive analysis with ethylene-methyl acrylate-glycidyl methacrylate terpolymer (EMA-co-GMA) and methyl methacrylate-butadiene-styrene terpolymer (MBS), the common toughener in PC/PBT alloy. The impact performance test results of PC/PBT alloys with different addition of SOG-03 showed that the brittle-ductile transition began when SOG-03 content reached 3 wt%. The microstructure, differential scanning calorimeter (DSC) and multi-extrusion process results of PC/PBT alloys all showed that SOG-03 tends to be dispersed in PBT phase and the dispersed SOG-03 presents typical rubber-toughened polymer morphology. The toughening efficiency of MBS on PC/PBT alloy was much lower than EMA-co-GMA and SOG-03, and showed a worse processing stability after multi-extrusion process and long-term thermal ageing properties. The EMA-co-GMA and SOG-03 toughened PC/PBT alloys showed an equivalent toughness, while the PC/PBT alloy with SOG-03 showed a better processing stability during the multi-extrusion process and long-term thermal ageing property when the thermal aging time is more than 600 h.

Progress in Research on Structural Ceramic Materials Toughened by Graphene

Graphene has excellent mechanical properties and unique physical/chemical properties,which make it have a good strengthening and toughening effect on structural ceramic materials.In recent years,it has received widespread attention and research.This article reviews the mixing and sintering processes in the preparation of graphene/ceramic com-posites,as well as the toughening mechanism of graphene on ceramic materials.It also looks forward to how to further enhance the toughening effect of graphene.

环氧树脂增韧体系对胶粘剂热性能的影响

本文对比考察了端羧基液体丁腈橡胶(CTBN)和核壳橡胶增韧剂对环氧树脂胶粘剂体系固化反应热、玻璃化转变温度(Tg)、膨胀系数以及拉伸剪切强度的影响。研究结果表明:CTBN和核壳橡胶均能降低环氧树脂胶粘剂体系的固化反应热,CTBN体系固化反应峰值温度升高,核壳橡胶体系固化反应峰值温度变化不大;CTBN和核壳橡胶的添加,均降低了胶粘剂体系的Tg,CTBN体系下降幅度大于核壳橡胶体系;CTBN和核壳橡胶的添加,均增大了胶粘剂体系的膨胀系数(<Tg时),CTBN体系增大幅度大于核壳橡胶体系;随着CTBN和核壳橡胶添加量的不断增加,拉伸剪切强度均呈现出先增加后降低的趋势。

POE-g-MAH增韧改性PA6的力学性能

研究了接枝马来酸酐的乙烯-辛烯共聚物(POE-g-MAH)对增韧改性尼龙6(PA6)力学性能的影响.结果表明:随着POE-g-MAH含量的增加,PA6的拉伸模量和强度及弯曲模量和强度均有所下降,但冲出强度和断裂伸长率均显著提高;增韧改性后PA6断面形貌明显成韧性断裂,且其熔体流动速率随POE-g-MAH含量增加而下降;当POE-g-MAH质量分数为25%时,增韧PA6的综合性能最佳,可用作PA柔性管材专用料.

POE-g-MAH对PA66共混体系性能的影响

讨论了POE-g-MAH含量、MAH接枝率对PA66/POE/POE-g-MAH共混物性能的影响。当POE-g-MAH含量为10wt%～15wt%时,PA66/POE-g-MAH共混物发生脆-韧转变;随POE-g-MAH含量增加,共混物的缺口冲击强度、断裂伸长率显著增大,拉伸强度、弯曲强度、弯曲模量、熔体流动速率、吸水率均明显下降。当POE-g-MAH接枝率为0.05wt%～0.2wt%时,PA66/POE/POE-g-MAH共混物发生脆-韧转变;随POE-g-MAH接枝率增加,共混物的缺口冲击强度、断裂伸长率增大,拉伸强度、弯曲强度、弯曲模量、吸水率变化不大,熔体流动速率下降。SEM照片和Molau实验表明,POE-g-MAH对PA66具有显著的增容增韧效果。

M-POE-g-MAH增韧PBT的力学性能和形貌

研究了一种新型增韧剂 (M POE g MAH )对PBT树脂的增韧效果。与传统的纯POE g MAH增韧剂(POE g MAH)进行对比 ,考察了增韧剂的组成、用量对共混物力学性能的不同影响 ,并结合共混物的室温缺口冲击断面SEM照片 ,分析了共混物发生脆韧转变所对应的微观形貌特征。实验结果表明 ,在M POE g MAH/PBT共混体系中 ,POE g MAH用量占体系 10 %左右时共混物发生明显的脆韧转变 ,而在传统的纯POE g MAH/PBT共混体系中 ,POE g MAH用量为 15 %左右才使共混物发生脆韧转变。M POE g MAH增韧PBT在性能和成本上具有较大的优势 ,所得共混物产品的性价比较高。

POE-g-MAH和PC协同增韧聚对苯二甲酸丁二酯的脆韧转变

研究马来酸酐接枝乙烯-辛烯共聚物弹性体(POE-g-MAH)和热塑性树脂(PC)协同增韧聚对苯二甲酸丁二酯的脆韧转变,借助扫描电镜(SEM)观察分析增韧体系的相形态和断口形貌,并对增韧机理进行探讨。结果表明,添加PC后,共混体系的脆韧转变在较低POE-g-MAH含量下发生。当PBT与PC质量配比为50/50时,共混物在POE-g-MAH含量为10%时获得超高韧性,达到78kJ/m2,同时拉伸强度达到52.5MPa。SEM分析认为,PC含量较高时,呈现极不规则的近似条状或片状的分散相结构,以及柔性界面层的存在是共混体系在较低弹性体含量下出现脆韧转变而获得高强韧性的主要机制。

热处理对PP／纳米SiO2／PA6／POE-g-MAH复合材料力学性能与结晶行为的影响

研究了不同热处理温度、热处理时间、冷却方式对PP/纳米SiO2/PA6/POE-g-MAH复合材料力学性能与结晶行为的影响。结果表明,随着热处理温度的升高,复合材料的缺口冲击强度直线下降,断裂强度与断裂伸长率显著提高;热处理时间的增加,对复合材料的缺口冲击强度、断裂伸长率和断裂强度影响显著,对拉伸强度影响较小;在复合材料结晶温度以下温度进行热处理,材料的综合力学性能下降,在结晶温度以上的温度进行热处理,采用快速冷却的冷却方式能够显著改善材料的综合力学性能。最佳热处理工艺:热处理温度为140℃,热处理时间为30min,水冷冷却。

PA6／POE-g-MAH共混物在缺口冲击与缺口拉伸实验中的脆韧转变

用缺口冲击和缺口拉伸实验研究PA6/POE-g-MAH共混物的脆韧转变。结果显示,POE-g-MAH含量对共混物脆韧转变的影响主要是POE-g-MAH含量对裂尖局部应变速率的影响。在缺口冲击和缺口拉伸实验中,随着POE-g-MAH含量增加,裂尖附近参与变形的范围增大,导致局部应变速率降低。当局部应变速率降低至某临界值时,材料的断裂发生脆韧转变。在缺口拉伸实验中,随着拉伸速度增加,PA6/POE-g-MAH共混物发生脆韧转变的POE-g-MAH含量增加。这可能是拉伸速度与POE-g-MAH含量对PA6/POE-g-MAH共混物裂尖局部应变速率共同影响的结果。

POE-g-MAH增韧半芳香尼龙的研究

使用马来酸酐接枝聚烯烃弹性体(POE-g-MAH),通过共混改性半芳香尼龙PA6T/66。制备了不同POE-gMAH含量的聚合物,并对其力学性能、热性能及动态力学性能进行了研究。结果表明,POE-g-MAH的加入,在不对基体PA6T/66的力学性能和热性能产生明显影响的同时,有效提高了材料的冲击性能。

PA6/POE-g-MAH/纳米SiO_2复合材料的形态和力学性能

研究了纳米SiO2和马来酸酐接枝POE(POE-g-MAH)对PA6/POE-g-MAH/纳米SiO2复合材料形态和力学性能的影响。结果表明,纳米SiO2含量小于或等于1份时,只有少量团聚;超过1份后,纳米SiO2有明显团聚现象;纳米SiO2和POE-g-MAH具有一定的协同增韧作用,在PA6/POE-g-MAH/纳米SiO2质量比为85/15/1时,复合材料的冲击强度达到最大,为PA6的10倍;复合材料的低温冲击强度也得到明显提高,达到PA6的3.3倍。

PET/POE-g-MAH的性能研究

利用熔融法 ,采用马来酸酐接枝乙烯 -辛烯共聚弹性体 (POE g MAH)增韧聚对苯二甲酸乙二醇酯 (PET) ,研究了热处理对PET/POE g MAH共混体系增韧效果的影响。结合共混材料的室温缺口冲击断面SEM照片 ,淬断刻蚀照片和宏观力学性能 ,分析了共混体系发生脆韧转变对应的微观形貌特征。结果表明POE g MAH与PET具有良好的相容性 ,热处理不但可以使PET/POE g MAH共混体系的拉伸强度增大 ,而且可以显著提高其冲击强度。

BP神经网络在POE-g-MAH/HDPE增韧PA6研究中的应用

运用BP神经网络研究了马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)/高密度聚乙烯(HDPE)对尼龙6(PA6)的增韧作用,并在此基础上建立了PA6/POE-g-MAH/HDPE复合材料各组分用量与复合材料冲击强度的关系模型。结果表明:该模型和实验结果基本吻合,可信度较高;当POE-g-MAH质量分数为12%,HDPE质量分数为16%时,PA6的缺口冲击强度达到95.02 kJ/m2。

POE-g-MAH对尼龙6的增韧改性

采用马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)对两种尼龙6树脂增韧改性,制备了不同增韧剂含量的增韧尼龙6材料。通过力学性能测试和SEM研究了增韧剂质量分数对其力学性能的影响,观察了POE-g-MAH/尼龙6复合材料冲击断面形貌。结果表明,随着增韧剂含量的增加,尼龙6的韧性显著提高,强度下降;且随着增韧剂的增多,在尼龙基体中形成有效的增韧剂聚集相起到改善韧性的作用;在两种流动性差异较大的尼龙6基体中,POE-g-MAH均表现优异的增韧效果。

PA66/POE-g-MAH/改性纳米高岭土复合材料的形态和力学性能

研究了改性纳米高岭土和马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)对PA66/POE-g-MAH/改性纳米高岭土复合体系的力学和形态的影响。结果表明:改性纳米高岭土和POE-g-MAH具有协同增韧的效果,PA66/POE-g-MAH/改性纳米高岭土质量比为100/20/0.2时,复合材料的冲击强度比PA66提高了7.3倍;低温冲击强度比PA66提高了2.7倍;形态研究表明:改性纳米高岭土的加入对POE-g-MAH具有助分散的作用。

PA1010/纳米橡胶/POE-g-MAH共混物的流变性能研究

用高压毛细管流变仪研究了PA1010/纳米橡胶/POEgMAH共混物的流变性能。结果表明,在240～270℃及剪切速率100～2500s-1时,熔体为假塑性流体。加入纳米橡胶明显地降低了共混物熔体的非牛顿指数,并且使尼龙1010的粘流活化能较大幅度地降低,但橡胶含量增加对粘流活化能影响不明显。随着橡胶含量的增加,熔体的粘度逐渐增大,橡胶含量为15%时达到最大值。

PA6／POE-g-MAH体系的结构与性能研究

以动态硫化及非动态硫化方法制备了马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)增韧的聚酰胺6(PA6) 共混物,研究了PA6／POE-g-MAH体系的力学性能以及POE-g-MAH在PA6中的分散状况。结果表明动态硫化 PA6／POE-g-MAH共混物的屈服强度、冲击强度、断裂伸长率及弯曲模量均高于非动态硫化方法制备的PA6／POE-g- MAH共混物,动态硫化的PA6／POE-g-MAH共混物可以在材料的刚性与韧性之间达到良好的平衡。扫描电子显微镜图像的统计分析表明,非动态硫化PA6／POE-g-MAH共混物中分散的橡胶相数均颗粒尺寸随组成中POE-g-MAH 的含量增大而不断增大,动态硫化的PA6／POE-g-MAH共混物中分散的橡胶相数均颗粒尺寸随POE-g-MAH含量的增大变化不大。