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《高分子材料科学与工程》2018,(10)
螺旋碳纳米管(HCNTs)由于其独特的三维螺旋形态及碳纳米管结构可望在新型功能和高强度复合材料领域发挥重要作用。文中研究了不同方式的HCNTs表面改性对环氧树脂复合材料力学性能的影响,并进一步分析了其强韧化机理。研究表明,通过γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)或聚乙烯亚胺(PEI)对HCNTs进行表面改性后与环氧树脂(EP)共混,能够显著提高复合材料的力学性能。KH560改性的HCNTs/EP复合材料冲击强度和拉伸强度分别提高了118. 4%与54. 1%; PEI改性的HCNTs/EP复合材料冲击强度和拉伸强度分别提高了101. 3%与70. 0%。分析认为,表面改性能够改善HCNTs与环氧树脂之间的界面相互作用,有利于两者之间的应力传递,从而使其力学性能得到进一步提高。 相似文献
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利用自行合成的端基含有活性基团的热致性液晶聚合物(LCPU)对不饱和聚酯(UP)/玻璃纤维(GF)复合材料改性。用DSC、TGA、热膨胀仪、DMA测试了共混物的热性能和动态力学性能并研究其结构与性能的关系,用扫描电镜(SEM)对材料断面的形态结构进行了研究。结果表明:当LCPU含量为2.5%~5%,材料的综合热性能较好,材料的玻璃化转变温度、热失重温度、维卡软化点温度都有所提高,热膨胀性能得到改善。SEM观察表明,LCPU的加入对提高材料的断裂能具有一定的作用。 相似文献
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聚氨酯丙烯酸酯共聚乳液的合成及其涂膜性能 总被引:2,自引:0,他引:2
传统的合成乳液,综合性能差.不使用有机溶剂,合成了高t<,g>(20.2℃)、低成膜温度(13.2℃)、力学性能较好的聚氨酯丙烯酸酯(PUA)共聚乳液,研究了n(NCO)/n(OH)、固化剂等因素对涂膜性能的影响.傅立叶红外光谱(FT-IR)证实,聚氨酯(PU)和聚丙烯酸酯(PA)发生了共聚反应.TEM和粒径分布测试表明,PUA乳液粒径为200 nm左右,分布较均匀.DSC分析表明:涂膜中PU链的硬段及PA分子链之间具有一定的相容性和共混程度.力学测试及涂膜综合性能测试显示,当n(NCO)/n(OH)为1.2~1.3,固化剂质量分数为1.2%~2.0%时,涂膜的力学性能、耐盐雾性能以及耐老化性能优异. 相似文献
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对纳米微晶纤维素(NCC)增强改性聚脲/丙烯酸树脂(PUA)复合涂膜的性能进行了研究。通过掺入占PUA不同质量分数的NCC来研究其对复合涂膜整体性能的影响。结果表明,随着NCC用量的增大,复合涂膜的拉伸强度先增大后减小。当NCC用量为5%时对涂膜的增强效果最佳,抗拉强度达到12.91 MPa,较未改性的复合涂膜提高了54.98%。而改性复合涂膜的吸水率呈现先减小后增大的趋势,NCC用量为5%左右时吸水率达到最小。5%NCC的加入对复合涂膜的热性能及透光性能影响不大,但改善了复合涂膜的耐高温性能和耐磨性能。 相似文献
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EPDM/POSS复合材料的阻燃性能 总被引:3,自引:0,他引:3
以自行合成的无机-有机杂化材料——笼形八苯基硅倍半氧烷(OPS)与三元乙丙橡胶(EPDM)、硫化剂制成新型复合材料,测定了材料的力学性能和氧指数(LOI)、UL-94阻燃性能,并利用热重分析仪考察了材料的热稳定性,利用锥型量热仪测试了材料的热释放速率等多种燃烧参数。结果表明,OPS复合的EPDM与纯EPDM相比,氧指数有所提高,释热速率降低,热稳定性提高,力学性能得到明显的改善。20份OPS的加入可以使拉伸强度增加一倍,初始热分解温度提高19℃,氧指数提高18.5%,热释放速率降低18.3%。 相似文献
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环氧树脂/超支化聚酯/纳米SiO2复合材料的制备及性能 总被引:1,自引:0,他引:1
采用超支化聚酯与聚硅酸溶胶共混改性环氧树脂,制备了环氧树脂/超支化聚酯/纳米SiO2三元共混体系纳米复合材料。研究了超支化聚酯/聚硅酸溶胶增韧改性环氧树脂固化体系的力学性能及热性能,通过X射线衍射(WAXD)、差示扫描量热(DSC)、热重分析(TGA)及扫描电镜(SEM)等测试手段对材料的微观相态结构与性能进行了表征。结果表明,超支化聚酯/聚硅酸的加入使纳米复合材料的力学性能和热性能得到明显提高。当纳米SiO2的含量为1%(质量分数,下同)时冲击强度比纯环氧树脂提高了10.48kJ/m2,材料的起始热分解温度也提高了27℃。 相似文献
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用作锂离子电池负极材料的包碳螺旋结构碳纳米管 总被引:1,自引:0,他引:1
以苯为碳源, 在900 ℃下采用TVD(thermal vapor deposition)法对螺旋结构碳纳米管(Helical carbon nanotubes, HCNTs)进行了包碳修饰, 采用XRD、SEM、TEM、BET 等检测方法对所制备材料进行了表征分析. 包碳后HCNTs的比表面积明显降低. 研究了包碳HCNTs用作锂离子电池负极材料的性能, 结果显示适量包碳不仅提高了HCNTs的首次库仑效率, 而且改善了其循环稳定性和倍率充放电性能. 当TVD包碳45 min、HCNTs增重约220 wt%时, 首次库仑效率从59.2%提高到77.8%, 在1.0C、2.0C、5.0C以及10.0C倍率下的放电比容量分别为265.6、245.7、196.0、163.2 mAh/g, 在10.0C下循环95次后放电比容量保持率为93.3%. 过多的碳包覆虽然会进一步提高材料的首次库仑效率和循环稳定性, 但会导致其倍率性能变差. 相似文献
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Z.Y. Nuru C.J. Arendse T.F.G. Muller M. Maaza 《Materials Science and Engineering: B》2012,177(14):1194-1199
We report on the microstructure and optical properties of AlxOy–Pt–AlxOy interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of AlxOy. The top and bottom AlxOy layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of AlxOy. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the AlxOy–Pt–AlxOy interference-type multilayer stack for use in high temperature solar-thermal applications. 相似文献
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Spectrally selective AlxOy/Pt/AlxOy multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both AlxOy layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of AlxOy/Pt/AlxOy multilayer absorber indicated the AlxOy layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively. 相似文献
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Integration of NiSix based fully silicided metal gates with HfO2 high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSix film. Ni content varies near the NiSi/HfOx interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSix/HfO2 interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSix/HfOx was found higher than that of poly-Si/HfO2, likely due to compositional non-uniformity of NiSix. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed. 相似文献
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In our previous works, we have shown that most existing ceramic superconductors can be considered to be built of superconductor-semiconductor composite and we have estimated the change in phonon spectrum of the intrinsic superconductor unit if a semiconductor unit is attached to it. Moreover, the proximity effect under the size quantization condition has been examined in the superconductor-semiconductor composite. Each of the stated effects by itself could causeT
c
enhancement in general as more semiconductor blocks are added to the system. We extend our study in this paper to analyze the combined actions of phonon spectral change and proximity effect without size quantization condition onT
c
variation in members of the Tl1 series of high-T
c
superconductors. Our results indicate that an optimumT
c
is obtained if the stated effects are included in the idealized unit cells of the superconductors made up of a superconductor-semiconductor array. 相似文献
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K. Racka I. Kuryliszyn M. Arciszewska W. Dobrowolski J.-M. Broto O. Portugall H. Rakoto B. Raquet V. Dugaev E. I. Slynko V. E. Slynko 《Journal of Superconductivity》2003,16(2):289-291
The Anomalous Hall Effect (AHE) was investigated in IV–VI ferromagnetic semimagnetic semiconductors of Sn1–x
Mn
x
Te codoped with either Eu or Er. The analysis of experimental data is as follows. Hall resistivity and magnetization showed that AHE coefficient R
s
depends on temperature and its value decreases with thetemperature increase. We observe that above ferromagnet–paramagnet transition temperature R
s
changes sign. We discuss the possible physical mechanisms responsible for observed temperature dependence of R
s
, particularly change of the sign. 相似文献
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A high-pressure technique was adopted to obtain perovskite-type . A new perovskite was characterized to have a cubic symmetry with ; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement. 相似文献
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The preparation conditions of the high TC ceramic superconductor Ba(Pb,Bi)O3 is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition. 相似文献
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S. Nomura J. Kuwata S.J. Jang L.E. Cross R.E. Newnham 《Materials Research Bulletin》1979,14(6):769-774
The electrostriction in crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP2 above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q11 = 1.6·10?2m4/C2, Q12 = ?0.86·10?2m4/C2, and Q44 = 0.85·10?2m4/C2. 相似文献
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The monoclinic-to-tetragonal structure transition of oxides V1?xMox02 with has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with to be semiconducting, while a metallic behavior was observed in the region . 相似文献