聚甲醛/泡沫铝合金互穿复合材料导热性能的研究

使用硅烷偶联剂KH570对孔隙率不同的泡沫铝合金进行表面改性后,通过注塑成型法制备了聚甲醛/泡沫铝合金互穿复合材料。采用傅立叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)和导热系数测试仪分别研究了改性后的泡沫铝合金的表面的红外结构、复合材料的界面结合问题以及所制备复合材料的导热性能。结果表明,硅烷偶联剂KH570成功接枝到了泡沫铝合金的表面;泡沫铝合金与聚甲醛两相界面结合良好;泡沫铝合金的充填提高了复合材料的导热性能。当泡沫铝合金孔隙率为60.48%~75.41%时,聚甲醛/泡沫铝合金互穿复合材料的导热系数随孔隙率(λ)的增大而降低,其导热系数在10.2945~17.6471 W/(m·K)之间。     

苎麻织物表面改性对其增强热固性聚乳酸复合材料力学及阻燃性能的影响

采用碱处理、硅烷偶联剂处理、碱+硅烷偶联剂复合处理、碱+阻燃剂+硅烷偶联剂复合处理对苎麻织物进行表面改性,采用模压工艺制备了苎麻织物增强热固性聚乳酸(PLA)复合材料。研究了4种表面改性方法对苎麻织物/PLA复合材料弯曲性能的影响,采用SEM研究了苎麻纤维与PLA基体之间的界面结合状况。结果表明:经过4种表面改性处理后苎麻织物/PLA复合材料的弯曲性能均有所提高,其中碱+硅烷偶联剂复合处理后提高幅度最大,苎麻织物/PLA复合材料的弯曲强度、模量分别提高了59.5%、51.9%。碱+阻燃剂+硅烷偶联剂复合处理后苎麻织物/PLA复合材料的弯曲强度、模量较未处理时分别提高了38.0%、66.8%;且苎麻织物/PLA复合材料60s点火时间的损毁长度为8.25cm,达到了美国DOT/FAA/AR-00/12要求的标准。SEM结果表明:改性处理后苎麻织物/PLA复合材料中纤维与树脂之间的界面结合更好。     

高分子基材料表面改性研究进展

大多数高分子材料表面硬度低、耐划伤性能差,影响了其使用寿命和应用范围。在高分子基体材料表面制备防护薄膜是一种简单有效的解决方法,成为表面防护的研究热点。然而,大多数高分子及其复合材料的表面自由能低,薄膜与基体间固有的界面粘附力较差,制约了其实际应用。文中探讨了机械啮合、化学键合和热力学粘附等三种主要的粘附机理,阐述了高分子基体材料表面改性的研究进展,指出了不同改性方法的优缺点,提出了薄膜界面粘附力研究存在的问题和发展方向。     

硅溶胶改性碳纤维对碳纤维/环氧树脂复合材料界面性能影响

以硅烷偶联剂和正硅酸乙酯(TEOS)为前躯体, 以固体酸-对甲苯磺酸为催化剂制备硅溶胶, 利用硅溶胶对碳纤维进行表面改性后, 以环氧树脂为基体, 制备碳纤维增强环氧树脂复合材料。利用SEM、 TEM、 万能试验机、 偏光显微镜等对表面改性前后的碳纤维形态、 力学性能及碳纤维/环氧树脂复合材料的界面性能进行表征, 研究了硅溶胶改性碳纤维对其复合材料界面性能影响。结果表明, 硅溶胶处理碳纤维后, 在碳纤维表面原位生成具有膜-粒结构的表面层, 改性后碳纤维的强度由2.41 GPa提高到3.00 GPa, 界面性能也得到了明显改善, 界面剪切强度(IFSS)提高了51.41%。     

硅烷偶联剂对玻璃纤维/聚氨酯复合材料性能的影响研究

采用硅烷偶联剂(KH550)对玻璃纤维进行表面处理,并对改性玻纤进行红外分析,结果证明硅烷偶联剂使玻璃纤维表面基团增加。用改性玻纤制备改性玻纤/聚氨酯复合材料,与原玻纤增强聚氨酯材料的力学性能及泡孔结构进行对比。结果表明:硅烷偶联剂处理能够提高玻璃纤维与聚氨酯基体的界面强度,改善玻璃纤维在聚氨酯基体中的分散情况,使玻璃纤维/聚氨酯复合材料的力学性能提高,同时改善复合材料的泡孔结构。     

环氧基团修饰多壁碳纳米管及其化学交联聚氨酯复合材料的性能

碳纳米管在高分子材料中的分散性能及其二者的界面结合力决定了其复合材料的性能。用H_2O_2-FeSO_4试剂处理多壁碳纳米管(MWCNTs)使其羟基化,再与硅烷偶联剂反应分别制备了缩水甘油醚氧丙基三甲氧基硅烷改性的MWCNTs(MWCNTs-KH560)和3-氨基丙基三乙氧基硅烷-环氧树脂改性MWCNTs(MWCNTs-E51),并和含羧基的聚氨酯(PU)混合制备了MWCNTs/PU复合材料,研究了不同链段环氧基团对复合材料性能的影响。结果表明,接枝环氧基团后,MWCNTs能明显地提高其复合材料的力学性能、热稳定性能和导电率。和MWCNTs-E51相比,MWCNTs-KH560/PU具有较高的上述性能,但断裂伸长率较低。分析认为,接枝的环氧基团可和PU链上的羧基发生开环反应而形成了化学交联结构,显著地提高了MWCNTs和PU之间的界面结合力。但MWCNTs-E51接枝的较长有机链段起增塑作用,且提高了MWCNTs之间的隧道电阻,从而降低了复合材料的力学性能和导电性能。     

稀土改性玻璃纤维对PTFE复合材料摩擦磨损性能的影响

分别用硅烷偶联剂SG-Si900(SGS)、含SG-Si900的稀土溶液(SGS/RES)和稀土溶液(RES)对玻璃纤维进行表面改性,考察了稀土改性玻璃纤维填充的PTFE复合材料在油润滑条件下的摩擦磨损性能,并用扫描电子显微镜(SEM)分析了磨损表面形貌.结果表明:与未经表面改性玻璃纤维填充的PTFE复合材料相比,经表面改性玻璃纤维填充的PTFE复合材料的减摩耐磨性能得到提高,以RES的作用最明显,SGS/RES次之,SGS第三;在油润滑条件下,稀土改性玻璃纤维填充的PTFE复合材料只出现了轻微磨损,这是由于玻璃纤维经稀土表面改性后极大地改善了玻璃纤维与PTFE基体之间的界面结合力,使稀土改性玻璃纤维填充的PTFE复合材料具有优异的摩擦磨损性能.     

新一代高导热金属基复合材料界面热导研究进展

热物理性质不同的材料之间存在界面热阻,界面热阻对热传输过程产生极大的影响,并在很大程度上决定了复合材料的导热性能。金刚石颗粒增强金属基复合材料(Metal matrix composites,MMCs)充分发挥了金刚石的高热导率和低热膨胀系数的优点,有望获得高的热导率以及与半导体相匹配的热膨胀系数,可满足现代电子设备在散热能力上提出的越来越高的要求,作为新一代电子封装材料已引起广泛关注。界面热导(界面热阻的倒数)既是决定复合材料导热能力的关键因素,也是研究的难点,复合材料制备工艺、界面改性方式(金属基体合金化或金刚石表面金属化)以及改性金属种类均会影响界面热导。详细论述了界面热导理论及实验研究的最新成果,并对金刚石/金属复合材料在未来研究中面临的主要问题进行探讨。     

硅烷偶联剂表面改性玄武岩纤维增强复合材料研究进展

表面改性是增强玄武岩纤维与基体材料之间结合性能的关键。综述了硅烷偶联剂表面改性以及酸、碱刻蚀,等离子处理辅助协同硅烷偶联剂表面改性玄武岩纤维的研究进展,介绍了硅烷偶联剂表面改性玄武岩纤维在聚合物基复合材料中的应用,并对发展趋势进行了展望,同时分析了硅烷偶联剂表面改性玄武岩纤维当前存在的问题。     

玻璃纤维表面纳米SiO_2改性对GF/PCBT复合材料力学性能的影响

为研究玻璃纤维(GF)表面纳米SiO2改性对GF增强树脂基复合材料力学性能的影响,利用真空辅助模压(VAMP)工艺制备了不同含量的纳米SiO2表面改性GF增强聚环状对苯二甲酸丁二醇酯(PCBT)复合材料。分析了GF表面改性对GF/PCBT复合材料力学性能的影响,研究了纤维表面改性对GF/PCBT复合材料抗湿热老化性能的影响规律。纤维拔出试验结果表明:经表面处理的GF/PCBT复合材料的界面剪切强度提高了1.16倍;采用含量为0.5wt%和2wt%(与树脂质量比)的纳米SiO2处理GF表面后,复合材料的三点弯曲强度分别提高1.5倍和1.67倍,弯曲模量分别提高1.03倍和1.17倍。SEM结果显示:当纳米SiO2用量为2wt%时,破坏后的纤维表面被树脂完全覆盖,树脂与纤维粘结良好。在湿热条件下,由于纳米SiO2颗粒的存在,水分子很难通过界面相扩散到改性后的材料内部,其抗湿热性能提高。     

UV–Ozone Interfacial Modification in Organic Transistors for High‐Sensitivity NO2 Detection

A new type of nitrogen dioxide (NO₂) gas sensor based on copper phthalocyanine (CuPc) thin film transistors (TFTs) with a simple, low‐cost UV–ozone (UVO)‐treated polymeric gate dielectric is reported here. The NO₂ sensitivity of these TFTs with the dielectric surface UVO treatment is ≈400× greater for [NO₂] = 30 ppm than for those without UVO treatment. Importantly, the sensitivity is ≈50× greater for [NO₂] = 1 ppm with the UVO‐treated TFTs, and a limit of detection of ≈400 ppb is achieved with this sensing platform. The morphology, microstructure, and chemical composition of the gate dielectric and CuPc films are analyzed by atomic force microscopy, grazing incident X‐ray diffraction, X‐ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, revealing that the enhanced sensing performance originates from UVO‐derived hydroxylated species on the dielectric surface and not from chemical reactions between NO₂ and the dielectric/semiconductor components. This work demonstrates that dielectric/semiconductor interface engineering is essential for readily manufacturable high‐performance TFT‐based gas sensors.     

改性碳纳米管处理碳纤维的效果表征

采用浓硫酸/浓硝酸氧化处理多壁碳纳米管(MWCNTs),再将氧化后的碳纳米管与硅烷偶联剂(KH560)进行接枝,制备了硅烷偶联剂表面化学修饰的MWCNTs。在此基础上,将改性前后的碳纳米管分散在环氧树脂体系中,涂覆处理碳纤维。研究处理前后碳纤维力学性能和界面性能的变化。通过红外光谱(FTIR)和透射电镜(TEM)分析,表明KH560已成功接枝到多壁碳纳米管上;通过分散性实验证明了改性后的碳纳米管分散性提高;对处理后的碳纤维进行力学性能测试,并用扫描电镜(SEM)观察分析断面形态变化,结果表明,当碳纳米管的含量为0.5%时,改性碳纳米管处理的碳纤维拉伸强度和拉伸模量分别提高23.83%和7.11%,界面性能增强。     

新型聚合物水泥胶浆界面剂粘结性能及作用机理研究

采用新型聚合物水泥胶浆作为界面剂以提高新旧混凝土之间的粘结性能,通过拉拔粘结强度与劈裂抗拉粘结强度实验对5种不同类型的聚合物水泥胶浆界面剂的粘结性能进行了测试,并利用扫描电镜(SEM)分析研究了丁苯聚合物水泥胶浆的界面增强机理。实验结果表明,5种聚合物乳液中,丁苯聚合物水泥胶浆具有较好的拉拔粘结性能,当优选m(水泥)∶m(DB-1乳液)=3∶2时,其7d、28d拉拔粘结强度分别达到1.83MPa、2.41MPa,相比水泥净浆空白样分别提高了144%、96%;在劈裂抗拉粘结强度方面,水平方向浇筑时劈裂抗拉粘结强度相对较高,当聚合物水泥胶浆的优选m(水泥)∶m(DB-1乳液)=3∶2,水平浇筑时其28d劈拉粘结强度达到2.96MPa,明显高于不掺界面剂的试样以及掺加其它配比界面剂的混凝土试样;经过微观测试分析,丁苯DB-1聚合物水泥砂浆内部界面过渡区(ITZ)相比空白样明显致密,表明丁苯聚合物的加入有效填充了水泥基材料内部的宏观与微观缺陷,提高了界面过渡区的密实程度。     

Combined AFM, XPS, and contact angle studies on treated indium-tin-oxide films for organic light-emitting devices

In the present work, surface modifications were performed on the indium-tin-oxide (ITO) substrates and the treated ITO surface properties were investigated by different characterization techniques. AFM and XPS methods were applied to measure surface roughness and chemical composition, respectively. Standard goniometry was used to determine contact angle and to calculate surface energy. Experimental results show that the ITO surface properties are subjected to the treatment methods which lead the surface to a certain degree of changes. Wettability of the modified surfaces was then monitored as a function of time elapsed after treatment and quantified. Furthermore, the polymer light-emitting electrochemical cells (LECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized. We observe that the electrical and optical performances of the polymer LECs are affected by the treatment methods on the ITO surface which result in the modification of interface formation and electrical contact of the ITO substrate with the polymer blend in the polymer LECs.     

Surface treatment of coir (Cocos nucifera) fibers and its influence on the fibers’ physico-mechanical properties

Coir, an important lignocellulosic fiber, can be incorporated in polymers like polyacrylate in different ways for achieving desired properties and texture. But its high level of moisture absorption, poor wettability and insufficient adhesion between untreated fiber and the polymer matrix lead to debonding with age. In order to improve the above qualities, adequate surface modification is required. In our present work, fiber surface modification by ethylene dimethylacrylate (EMA) and cured under UV radiation. Pretreatment with UV radiation and mercerization were done before grafting with a view to improve the physico-mechanical performance of coir fibers’. The effects of mercerization on shrinkage and fiber weight losses were monitored at different temperature and alkali concentration. We observed that, fiber shrinkage is higher at low temperature and 20% alkali treated coir fibers yielded maximum shrinkage and weight losses. It was found that higher shrinkage of the polymer grafted fiber showed enhanced physico-mechanical properties. The grafting of alkali treated fiber shows an increase of polymer loading (about 56% higher) and tensile strength (about 27%) than 50% EMA grafted fiber. The fiber surface topology and the tensile fracture surfaces were characterized by scanning electron microscopy and were found improved interfacial bonding to the modified fiber–matrix interface.     

锂离子电池硅基负极界面反应的研究进展

硅作为一种极具潜力的锂离子电池负极材料,已引起研究者的广泛关注。然而硅材料储锂过程中伴随着巨大的体积变化,导致电极/电解液界面不稳定,是限制硅电极商业化的主要因素之一。深入了解硅负极的界面反应机理,有助于改善硅负极的界面性质,进而提高硅负极的电化学性能。本文综述了硅负极界面反应的演化机制,包括Li-Si合金化过程、硅表面氧化硅的反应和表面纯化膜的形成,并讨论了其对硅电化学性能的影响。     

The effect of flow type and chemical functionalization on the dispersion of carbon nanofiber agglomerates in polypropylene

Two melt mixing methods generating flow with different characteristics are compared to study the dispersion of 5% w/w carbon nanofibers in polypropylene, namely conventional twin-screw extrusion and the simple application of a converging/diverging flow sequence to the composite melt. The effect of nanofiber surface modification and compatibilization with polypropylene modified with maleic anhydride is also studied. The dispersion of the nanofiber agglomerates through the polymer, the electrical properties of the resulting composites and nanofiber/polymer interface achieved under the different mixing conditions are analyzed. The converging/diverging flow sequence generated a better dispersion as compared with the twin-screw extruder.     

无机组分对聚酰亚胺杂化薄膜电性能的影响

初步探讨了聚酰亚胺薄膜在电场作用下的电学行为,采用溶胶-凝胶工艺制备了聚酰亚胺/二氧化硅纳米杂化薄膜,并对薄膜进行浸水24 h处理,利用原子力显微镜对制备的薄膜进行表面形貌表征,讨论了无机组分SiO2和水对薄膜电性能的影响.结果表明:无机组分的引入及两相间的界面形态将对杂化薄膜的电学性能产生重大的影响;偶联剂的引入使得两相间产生紧密的微相结合,并对电性能产生一定的影响.     

Ag-modified ZnO nanorods and its dual application in visible light-driven photoelectrochemical water oxidation and photocatalytic dye degradation: A correlation between optical and electrochemical properties

In this work, Ag-ZnO composite was prepared at different weight percentages using a modified hydrothermal method for application to the photoelectrochemical (PEC) water oxidation and photocatalytic dye degradation. The resulting samples were studied using structural, surface, optical and photoelectrochemical (PEC) characterization methods. The surface plasmon resonance (SPR) of the optimal catalyst played an essential role in the synergistic improvement of the optical response and the photoinduced charge carrier separation process. The optimal Ag modified ZnO (3 wt% of Ag) showed superior photocatalytic and water oxidation performance. The inclusion of Ag has also played a vital role in the defect concentration and the Schottky junction at the metal–metal oxide interface. As a result, the PEC behavior of the optimal samples showed drastic improvements in terms of water oxidation current response under visible light illumination. Consequently, the photocatalytic performance of the samples also exhibits a linear relationship with the PEC water oxidation performance. The PEC and photocatalytic performance of the optimal sample showed almost five and seven times superior performance than the pristine ZnO in terms of photocurrent value and rate constant value, respectively. This can be attributed to the existence of the Schottky junction leading to the minimum charge transfer resistance and better charge transport across the interface. The superiority of the optimal sample is explained in terms of the physicochemical properties and electrochemistry of the material. To the best of the authors’ knowledge, this is the first report on the role of optimal Ag content in ZnO for its dual application. The combined study offering complete information, the work provides guidelines for noble metal-modified catalyst research moving forward.     

Effect of the presence of excess ammonium ions on the clay surface on permeation properties of epoxy nanocomposites

Epoxy nanocomposites with commercially and self-modified montmorillonites of different cation exchange capacities carrying ammonium modifications of various chemical architectures were synthesized using solution casting approach. The commercially treated montmorillonites were observed to contain a large excess of unbound ammonium ions on the surface, which had a negative impact on the permeation properties of the composites owing to the suspected interactions of these unbound ammonium ions with the epoxy polymer. The permeation behavior was significantly improved when self-modified clays free of any excess ammonium modification were used. The microstructure development was unaffected by the physical state of the clay surface indicating that the potential changes in the polymer properties at the interface as well as interfacial interactions in the composites carrying the commercially modified clays may have led to increase in the free volume. Optimal preparation of the clay surface holds the key to achieve enhancement in the composite performance.