共查询到20条相似文献,搜索用时 78 毫秒
1.
《高分子材料科学与工程》2015,(6)
用等离子体在氧气环境对芳砜纶(PSA)纤维进行表面改性。分析纤维改性前后断裂强度、摩擦性能和润湿性能的变化。用场发射扫描电子显微镜和X射线光电子能谱仪分析纤维表面的形貌和化学元素变化。结果表明,等离子处理后的芳砜纶纤维,断裂强度变化较小,摩擦性能增强,润湿性能有大幅度提高;纤维表面随处理时间延长粗糙度增加,纤维表面碳元素含量下降、氧元素含量增加,纤维表面极性基团增加。 相似文献
2.
用扫描电子显微镜观察Technora纤维表面物理形貌并测量单丝纤维的拉伸强度以分析等离子体处理对纤维本体性能的影响,再用层间剪切强度和吸水率分别表征复合材料在室温干态和高温湿态下的界面性能,研究了等离子体处理对Technora纤维复合材料界面性能的影响。结果表明,用等离子体处理后纤维表面的物理形貌发生了显著变化,复合材料的层间剪切强度由未处理时的15.74 MPa提高到24.93 MPa,提高的幅度高达58.4%;同时,复合材料的吸水率下降而本体性能基本不受影响。上述结果表明,等离子体对Technora纤维的表面改性能有效地改善其复合材料的界面性能。 相似文献
3.
纤维表面处理对CF/PAA复合材料界面性能的影响 总被引:1,自引:0,他引:1
采用多结构形态倍半硅氧烷(VMS—SSO)涂层结合等离子活化纤维表面的方法对碳纤维(CF)改性,研究了纤维表面处理对碳纤维/聚芳基乙炔复合材料界面性能的影响.结果表明,等离子活化前后纤维表面涂层处理使材料的ILSS分别提高25%和45%,在碳纤维与树脂之间引入了过渡层.等离子活化纤维在碳纤维与涂层间通过VMS-SSO引入了化学键连接.含活性官能团的多形态倍半硅氧烷涂层在等离子活化纤维前后处理碳纤维,都能提高复合材料的界面性能.但是效果不同.其原因是,碳纤维与树脂间相互作用的不同,前者主要是过渡层效应,后者在碳纤维与树脂间引入了化学键. 相似文献
4.
5.
使用KMnO4、NaOH、阻燃剂、硅烷对剑麻纤维进行表面处理。采用单丝拉伸和微脱粘方法分别测试了剑麻纤维的拉伸性能及其与改性丙烯酸酯、环氧树脂的界面性能,考察了吸湿水对剑麻纤维表面形貌、拉伸性能及其与树脂界面粘结的影响,分析了相应的破坏模式。结果表明,经过表面化学处理后剑麻纤维的拉伸强度和模量均有不同程度的下降,其中经KMnO4和硅烷处理后,纤维拉伸强度下降了44%,经NaOH处理后其拉伸强度降低了27%,阻燃剂处理对剑麻性能的影响不明显。表面化学处理还会降低剑麻纤维与改性丙烯酸酯的界面粘结强度,其下降的幅度与纤维拉伸强度下降程度不一致,阻燃剂处理的剑麻/改性丙烯酸酯的界面强度最低,仅为2.0 MPa,较未处理剑麻纤维复合体系下降了80%。经硅烷处理后,剑麻纤维的吸水率下降,吸水后其拉伸性能保留率高于未处理剑麻纤维。湿态条件下未处理剑麻纤维与环氧树脂的界面强度为6.6 MPa,高于硅烷处理剑麻/环氧树脂的界面强度,其断口形貌表明硅烷处理可导致微纤之间的弱粘结,从而降低了剑麻纤维自身及其与树脂的界面性能。 相似文献
6.
在空气环境下用等离子体对芳砜纶(PSA)纤维进行表面改性,研究纤维改性前后断裂强度、摩擦性能和润湿性能的变化。用场发射扫描电子显微镜(FESEM)和X射线光电子能谱仪(XPS)分析纤维表面的形貌和化学元素变化。结果表明:芳砜纶纤维经等离子体改性后,纤维摩擦性能和润湿性能明显提高;纤维的断裂强度无明显变化;纤维表面碳元素含量明显下降,同比下降11.15%,氧和氮元素含量明显增加,同比分别上升49.14%和15.95%,纤维表面极性基团增加。综合考虑实验的最佳工艺参数为40Pa、100 W、2min。 相似文献
7.
以2,5-二羟基对苯二甲酸(DHTA)为改性单体,采用化学共聚改性的方法,合成了大分子链上含有羟基基团的聚对苯撑苯并二噁唑(PBO)与DHTA 的共聚物(DHPBO),并通过液晶纺丝技术得到了DHPBO 纤维。利用FTIR、接触角等分析手段对其化学结构和纤维表面性能进行了表征,并通过微脱粘实验和SEM评价了DHPBO纤维与环氧树脂基体的界面剪切强度。结果表明:50 mol%DHTA的加入使水在PBO纤维表面的接触角由71.4° 减小到50.7°,乙醇在PBO纤维表面的接触角由37.2° 减小到27.4°;当DHTA含量为20 mol%时,DHPBO纤维的表面自由能增加到43.96 mJ/m2,比PBO纤维提高了23.83%。当 DHTA含量为10 mol%时,DHPBO纤维与环氧树脂的界面剪切强度为18. 87 MPa,比PBO纤维与环氧树脂的界面剪切强度提高了92.55%。 相似文献
8.
9.
10.
11.
Cen C Thiel S Hammerl G Schneider CW Andersen KE Hellberg CS Mannhart J Levy J 《Nature materials》2008,7(4):298-302
Experimental and theoretical investigations have demonstrated that a quasi-two-dimensional electron gas (q-2DEG) can form at the interface between two insulators: non-polar SrTiO3 and polar LaTiO3 (ref. 2), LaAlO3 (refs 3-5), KTaO3 (ref. 7) or LaVO3 (ref. 6). Electronically, the situation is analogous to the q-2DEGs formed in semiconductor heterostructures by modulation doping. LaAlO3/SrTiO3 heterostructures have recently been shown to exhibit a hysteretic electric-field-induced metal-insulator quantum phase transition for LaAlO3 thicknesses of 3 unit cells. Here, we report the creation and erasure of nanoscale conducting regions at the interface between two insulating oxides, LaAlO3 and SrTiO3. Using voltages applied by a conducting atomic force microscope (AFM) probe, the buried LaAlO3/SrTiO3 interface is locally and reversibly switched between insulating and conducting states. Persistent field effects are observed using the AFM probe as a gate. Patterning of conducting lines with widths of approximately 3 nm, as well as arrays of conducting islands with densities >10(14) inch(-2), is demonstrated. The patterned structures are stable for >24 h at room temperature. 相似文献
12.
A method to realize room-temperature operation of a multifrequency Er-doped fiber laser with low-frequency shift feedback placed within a linear laser cavity is theoretically proposed and experimentally demonstrated. Simultaneous multiwavelength lasing with 0.5 nm wavelength spacing is experimentally demonstrated by applying a sinusoidal signal of 10 kHz to a fiber phase modulator inserted within the linear cavity to prevent single wavelength steady-state oscillation. In the linear cavity, an all-polarization-maintaining fiber Sagnac loop is used as a periodic filter, and a single-mode fiber loop with a polarization controller is used as a partial reflector and also as an output port. 相似文献
13.
14.
F. Muktepavela G. Bakradze V. Skvortsova E. Tamanis S. Stolyarova 《Materialwissenschaft und Werkstofftechnik》2005,36(10):513-517
Properties of interfaces in solid state metal/oxide joints (Al/SiO2, Al/MgO, Al/glass, Mg/MgO, Mg/SiO2, In/glass etc.) are reported. The interfaces were formed at plastic deformation of metal on the oxide surface at room temperature. Their structure, chemical composition, and micromechanical properties were studied by the AFM, XRD, SIMS, optical microscopy, and precision microindentation techniques. A noticeable adhesion was observed for metals with high affinity for oxygen and only in the regions of the maximum shear stress. Formation of an interfacial reaction zone with an oxygen concentration gradient is detected. In this zone metals are nanostructured and noticeably hardened. The effect of mechanoactivation is considered as a result of physical and chemical interaction and formation of nanostructures in deformed metal/oxide systems. 相似文献
15.
16.
In order to investigate the mechanical properties of Gd123 single-grain bulk superconductors fabricated using a modified quench and melt growth method, tensile tests in the direction parallel and perpendicular to the c-axis have been carried out at 293 K by using the small specimens cut from bulk superconductors. As for the mechanical properties perpendicular to the c-axis, there was no significant difference between those in the crystal growth direction and those perpendicular to it. While the average value of the Young’s modulus of the bulk sample with 33.0 mol%-Gd211 secondary phase particles, 118 GPa, was higher than that of the bulk sample with 28.7 mol%-Gd211, 111 GPa, the average value of the tensile strength of the former, 36 MPa, was lower than that of the latter, 40 MPa. The tensile strength and the Young’s modulus in the c-axis, 10 MPa and 37 GPa, were quite low compared with those mentioned above. Poisson’s ratio based on the transverse strain in the c-axis, 0.15, was significantly smaller than that perpendicular to it, 0.30. In the specimens with higher length, however, the difference was decreased to some extent. With regard to the anisotropy of the Poisson’s ratio, the effect of a pre-existing micro-crack opening in the c-axis direction was discussed coupled with the constraints at the interfaces between the specimen and the sample holder. 相似文献
17.
Fe---Mn---Al alloy steel has undergone many significant developments during the past few years, and it is considered to be a steel of high strength and toughness. Studies and test results have shown that Fe---Mn---Al is a good potential replacement for conventional stainless steels which contain expensive nickel and chromium additions. Recently, it has been found that strain-induced martensitic transformation at room temperature is possible in austenitic Fe---Mn---Al alloy. Further study has shown that the ′ martensite can improve the mechanical properties of these Fe---Mn---Al alloys. However, as the aluminium content increases, the strain-induced phase transformation is inhibited. Moreover, the mechanical properties of these materials are very dependent on the aluminium content. 相似文献
18.
《Materials Letters》2007,61(23-24):4471-4473
Cubic phase CdSe nanocrystals were prepared through a novel ultrasonic activation double-phase approach at room temperature. The band-edge emissions with the band centered at 452, 478, 496, and 511 nm and the surface state charge carrier recombination emissions from around 520 to 590 nm were observed for the CdSe with diameters of 1.4, 1.7, 1.9 and 2.1 nm, respectively. Those fluorescence emission spectra calculated chromaticity coordinates fall well within the white, white, green and yellowish green colors with quantum yield of about 1–2%. 相似文献
19.
20.
To elucidate the effect of superheated steam (SHS) treatment of carbon fiber on the adhesion to epoxy resin and surface states, virgin unsized carbon fiber was exposed to SHS with or without N2 in the temperature range of 500–800 °C. The interfacial shear strength (IFSS) between the carbon fiber and epoxy resin was successfully improved by SHS treatment with N2, and the IFSS of fiber treated above 700 °C was the same as or higher than that of a commercial sized fiber. SHS treatment without N2 resulted in an increase of total acidic groups on the fiber surface accompanied with the increase of phenolic hydroxyl groups, whereas that with N2 resulted in a simultaneous increase of total acidic and basic functional groups. The significant improvement in the IFSS after SHS treatment with N2 is considered to be due to the increase of basicity on the fiber surface. 相似文献