共查询到20条相似文献,搜索用时 78 毫秒
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利用硅烷偶联剂(KH-550,KH-560,KBM-7103)对低碳钢表面进行预处理,制备了聚乙烯(PE)涂层,通过对涂层的结合强度、抗热震性能等实验,研究了硅烷化处理对涂层性能的影响.结果表明:KH-560处理法能显著提高PE涂层的结合强度,比砂纸打磨、喷砂处理分别提高了40.3%,13.2%,而KH-550,KBM-7103不能显著提高PE涂层的结合强度;对于PE涂层的硅烷化处理,适宜的KH-560的浓度为5%(体积分数),水解时间为48h;"喷砂 KH-560"处理法抗热震实验后涂层的结合强度仅降低了10.9%,远低于其他处理方法热震后的下降幅度. 相似文献
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采用聚乙烯亚胺(Polyethyleneimine,PEI)作为表面活性剂对工业用β-SiC超细粉体进行表面改性,采用离心式喷雾干燥技术对碳化硅浆料进行干燥。通过扫描电镜、X射线衍射仪、红外光谱仪、粉体综合测试仪测试了改性前后粉体的形貌、表面性质、粒度及流动性。结果表明:PEI在粉体表面形成了包覆层,使粉体团聚现象减少;喷雾干燥大大地提高了粉体的流动性,综合流动性指数由原粉的44增加到88;改性并没有改变粉体内部的物相与结构;PEI仅仅是吸附包覆,通过空间位阻效应使得粉体稳定分散。 相似文献
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采用水热法利用两亲性聚乙烯基吡咯烷酮(PVP)对CNTs进行了表面修饰,通过TGA、FT-IR、SEM、接触角分析研究了改性CNTs的表面性质和分散特性.实验结果表明:水热法较常用的常压法相比,可以提高CNTs的PVP包覆率,且使PVP同CNTs之间具有更强的作用力,同时使处理效率有较大提高;PVP用量、保温时间和PV... 相似文献
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采用不同类型的硅烷偶联剂对钛酸钡进行表面修饰,实施接枝聚合,制备聚苯胺/钛酸钡核壳结构的复合粒子.借助SEM、XRD和TG等分析方法对复合粒子的表观形貌和结构进行表征,应用Gaussian 03软件对硅烷偶联剂分子在钛酸钡表面接枝的几何构型进行计算.理论计算与实验结果表明,采用硅烷偶联剂后,在钛酸钡表面有效地实施了接枝聚合,硅烷偶联剂的类型对包覆量和复合粒子的密度有着显著的影响,反应型的硅烷偶联剂能够更好地作用于钛酸钡的表面,形成稳定核壳结构的复合粒子. 相似文献
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碳化硅晶须补强氧化铝复合材料的制备及其力学性能 总被引:5,自引:0,他引:5
本论文利用商用γ-Al2O3粉体和上海硅酸盐所制备的碳化硅晶须,通过热压工艺来制备碳化硅晶须补强氧化铝复合材料.当晶须含量为30vol%时,室温下复合材料的抗弯强度为812±38MPa,断裂韧性为8.8±0.1MPa·m1/2;在1200℃、Ar气氛下,分别为560±61MPa和6.1±0.4MPam1/2.在氮气氛下,由于晶须的损伤易导致材料的力学性能下降.添加剂可降低复合材料的烧结温度,但不利于其力学性能.显微结构观察发现,不同温度下,AS复合材料的增韧机理有变化. 相似文献
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Treated polyethylene fibres as reinforcement for epoxy resins 总被引:2,自引:0,他引:2
Ultra-high-modulus polyethylene (UHMPE) fibres were treated in order to develop favourable surface and, possibly, microstructure characteristics. The main aim was to eliminate the microfibrillar morphology of the fibre and improve interfacial bonding between fibre/matrix so that better compressive properties can be achieved in reinforced resins. Calendering at 130 °C was performed, and the surface treatment used oxidative solutions. Adhesive bonding to epoxy matrices was highly improved in chromosulphate-treated material exceeding that of a commercial, corona-treated product, but the mechanical properties of these fibres deteriorated. Calendering did not significantly affect fibre strength and only improved adhesive bonding slightly. The use of these treated reinforcements is expected to improve the performance of composite materials, especially at low fibre volume fractions, because of their improved interfacial characteristics. 相似文献
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Synthesis of uniformly dispersed carbon nanotube reinforcement in Al powder for preparing reinforced Al composites 总被引:2,自引:0,他引:2
Xudong Yang Chunsheng Shi Chunnian He Enzuo Liu Jiajun Li Naiqin Zhao 《Composites Part A》2011,42(11):1833-1839
In order to obtain homogeneously dispersed carbon nanotube (CNT) reinforcement with well structure in Al powder, a novel and simple approach was developed as a means of overcoming the limits of traditional mixing methods. This process involves the even deposition of Ni catalyst onto the surface of Al powder by impregnation route with a low Ni content (0.5 wt.%) and in situ synthesis of CNTs in Al powder by chemical vapor deposition. The in situ synthesized CNTs with well-crystallized bamboo-like structure in the composite powders can obviate the reaction with Al below 1000 °C. The feasibility of fabricating CNT/Al composites with high mechanical properties using the as-prepared composite powders was proved by our primary test, which indicated that the compressive yield stress and elastic modulus of 1.5 wt.%-CNT/Al composites synthesized by hot extrusion are 2.2 and 3.0 times as large as that of the pure Al matrix. 相似文献
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Sodium tungsten bronze powders were synthesized by thermal reduction of a gas/melt system at high temperature. Samples having
a cubic structure with different compositions were prepared. The initial melt included Na2WO4, WO3 and 10–40% mol. NaCl while the reducing gas was hydrogen at 750 °C. An original mechanism of controlling the powders size
and distribution was suggested and discussed. A quantitative novel and simple method to determine the bronze composition based
on TGA data was developed. An increase in the NaCl content led to a decrease of the crystals size and improved the powder
uniformity. Fine powders, in the 2–5 μm size range, were synthesized from melt with 40% mol of NaCl. The stoichiometry parameter
x of the obtained bronzes ranged from 0.8 to 0.92. An excellent agreement between x values determined by the classical XRD route and the proposed TGA method was demonstrated. 相似文献
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《Composites Part A》1999,30(3):369-373
An alternative processing route for polyethylene–polyethylene composites has been developed. The processing route includes an impregnation step in a suspension of polyethylene powder in propanol. For this step an impregnation and winding machine has been constructed. Further processing steps are the preparation of prepregs and hot compacting to form PE–PE composites. The influence of the impregnation and winding parameters on the fibre volume fractions of the resulting composites are discussed. The mechanical properties of unidirectional reinforced PE–PE composites parallel and perpendicular to the fibre direction are shown in the results of tensile and compression tests. Finally, the failure mechanisms are described by SEM investigations. 相似文献
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Hydrophobic cellulose nanofibers (CNFs) were prepared by surface modification using alkenyl succinic anhydride (ASA). The hydrophobicity of CNFs was varied by changing the degree of substitution (DS) from 0 to 0.83. Modified CNFs were mixed with high-density polyethylene (HDPE) using a twin-screw extruder and the resulting composites were injection molded. The tensile properties initially improved with increasing DS up to ∼0.3–0.5, and then decreased with further substitution. The tensile strength and modulus of 10 wt.% HDPE/CNF composites containing 8.8 wt.% ASA (DS: 0.44) were 43.4 MPa and 1.97 GPa, respectively. These values were both almost 70% higher than those of composites containing unmodified CNF, and 100% and 86% higher, respectively, than those for pure HDPE. X-ray computed tomography measurements showed that CNFs modified with a DS of 0.44 were dispersed uniformly within the resin matrix, whilst unmodified CNFs and those modified with a DS of 0.77 agglomerated within the composites. 相似文献
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Glass-fiber reinforcement of in situ compatibilized polypropylene/polyethylene blends 总被引:1,自引:0,他引:1
Ch. Tselios D. Bikiaris P. Savidis C. Panayiotou A. Larena 《Journal of Materials Science》1999,34(2):385-394
Polypropylene and low-density polyethylene (LDPE) were melt-blended at proportions 75/25, 50/50, and 25/75 w/w, respectively. These blends were reinforced with two types of glass fibers added at an amount of 20 wt %: the E-type fibers without any surface treatment and the M-type fibers, which were treated with y-methacryloxy propyltrimethoxy silane coupling agent. Poly(propylene-g-maleic anhydride) with 0.8 mol % maleic anhydride content and poly(ethylene-co-vinyl alcohol) with 7.5 mol % vinyl alcohol content were added at a 50/50 w/w proportion as in situ reactive compatibilizers at an amount of 10 wt %. The thermoplastic composite materials have higher tensile strength as well as impact strength compared to the unreinforced blends. The simultaneous process of the in situ blend compatibilization, along with the incorporation of glass fibers in the thermoplastic matrix, leads to a significant improvement of the mechanical properties as compared to the properties of the composite materials with the uncompatibilized matrix. Scanning electron microscopy and micro-Raman spectroscopy have been used to study the adhesion of the thermoplastic matrix onto the glass fibers. Significantly better adhesion characteristics were observed in the composites containing M-type glass fibers, with LDPE adhering the most on the fibers. This better adhesion was reflected in the improved mechanical properties of the composites. 相似文献
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Polyethylene is one of the most important industrial polymers and is also one of the most challenging polymers to be characterized by mass spectrometry. We have developed a substrate-assisted laser desorption/ionization (LDI) mass spectrometric method for polyethylene analysis. In this method, cobalt, copper, nickel, or iron metal powders are used as a sample substrate and silver nitrate is used as the cationization reagent. Using a conventional UV LDI time-of-flight mass spectrometer, intact oligomer ions having masses up to 5000 u can be detected. Cobalt is found to produce spectra with the highest signal-to-noise ratio and the lowest level of fragmentation. Cobalt powder size is shown to have some effect on the spectra produced. The best results are obtained with the use of cobalt powders with diameters ranging from 30 to 100 microm. Fragmentation cannot be totally eliminated, but the fragment ion peaks can be readily discerned from the intact polyethylene ions in the substrate-assisted LDI spectrum. Thus, the average molecular masses of low-mass polyethylene samples can be determined by using this method. A rapid heating model is used to account for the effectiveness of using the coarse metal powders to assist the analysis of intact polyethylene molecules by LDI. 相似文献
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Kärkkäinen AH Tamkin JM Rogers JD Neal DR Hormi OE Jabbour GE Rantala JT Descour MR 《Applied optics》2002,41(19):3988-3998
Direct photolithographic deforming of hybrid glass films is used to fabricate optical structures. The structure is fabricated in polyethylene-oxide-acrylate modified hybrid glass films with (1) binary and gray-scale photomasks using a mercury UV-lamp exposure and (2) maskless UV-laser patterning. Fabrication of isolated lenslets, lens arrays, and gratings is presented, including the associated exposure patterns. The hybrid glass material yields light-induced deformation peak-to-valley (p.v.) heights up to 12.8 microm with mercury UV-lamp exposure and p.v. deformation heights up to 6.8 microm with 365-nm UV-laser exposure. The fabricated lenslets' surface data are presented as Zernike-polynomial fit coefficients. Material synthesis and processing-related aspects are examined to understand and control the material's deformation under exposure. The hybrid glass material exhibits a maximum spectral extinction coefficient of 1.6 x 10(-3) microm(-1) at wavelengths ranging from 450 to 2,200 nm and has a refractive index of 1.52 at 632.8 nm. The fabricated structures exhibit rms surface roughness between 1 and 5 nm. 相似文献