蜂窝结构材料用国产芳纶纸性能分析

介绍了芳纶纸蜂窝的特点和应用现状,简述了我国YT822型蜂窝结构材料用芳纶纸的性能,对比研究了国内产品与国外同类产品的性能差异。实验结果表明,YT822型芳纶纸的各项性能达到或接近进口T722芳纶纸的性能,国内生产的芳纶纸与酚醛树脂等材料复合制成的芳纶纸蜂窝夹芯能够满足使用要求。     

芳纶纸蜂窝芯条胶与国产芳纶纸的匹配性研究

本文探讨了J80芯条胶与国产YT822芳纶纸的匹配性,分析了芯条胶胶液黏度和涂胶辊参数对国产YT822芳纶纸浸润的影响规律。研究表明,J80芯条胶的胶液黏度在25s时,浸润性最好,蜂窝的节点强度最高;选择出2. 75规格蜂窝网纹宽度为2. 2mm、网纹深度为0. 17mm的涂胶辊,制作出的蜂窝格形更均匀饱满,孔格规整性好。     

对位芳纶蜂窝芯与间位芳纶蜂窝芯的性能对比研究

对比了使用对位芳纶纸制备的HN系列蜂窝芯与间位芳纶纸制备的YT系列蜂窝芯的主要力学性能及抗燃烧性能.结果表明,由对位芳纶纸制备的HN系列蜂窝芯的主要力学性能远远优于间位芳纶纸制备的YT系列蜂窝芯,但其抗燃烧性能仍有待改进.     

芳纶纸蜂窝酚醛树脂与国产芳纶纸的匹配性研究

本文探讨了酚醛树脂与国产YT822芳纶纸的匹配性,分析了树脂浓度和浸胶工艺对国产YT822芳纶纸浸润的影响规律。研究结果表明,当树脂胶液比重为0.96~0.97时,浸润性最好,上胶量最多;当浸胶工艺参数平置时间为45~60s、树脂胶液比重为0.96~0.97、流淌时间为65~85s时,蜂窝密度均匀性会有显著的提高。     

我国芳纶绝缘纸与国外同类产品的性能比较

简述了我国YT564型芳纶绝缘纸的性能,对比研究了与国外同类产品的性能差异。实验结果表明,YT564型芳纶纸的各项性能达到或接近进口T464型芳纶纸的性能,国内生产的芳纶纸与聚酯薄膜复合制成的柔软复合绝缘材料(YMY)能够满足使用要求。     

开槽芳纶纸蜂窝芯与有孔芳纶纸蜂窝芯的对比分析

通过压缩性能和剪切性能实验,对同一密度的传统芳纶纸蜂窝芯、开槽芳纶纸蜂窝芯以及有孔芳纶纸蜂窝芯的主要力学性能进行了对比分析。实验表明,同一密度的传统蜂窝芯的压缩性能和剪切性能优于两种特殊蜂窝芯,但两种特殊蜂窝芯的主要力学性能能够达到传统芳纶纸蜂窝芯标准中出厂检验指标值的77%以上,能够满足多数特殊结构的使用要求。对两种特殊芳纶纸蜂窝芯的制造工艺和实际应用进行了对比分析,指出了各自的优势和劣势。两种特殊蜂窝芯的W向剪切模量均高于指标值。开槽蜂窝芯较有孔蜂窝芯制造工艺简单、制造周期短、制造成本低,但有孔蜂窝芯制造精度更高、应用范围更加广泛。     

国产间位芳纶纸蜂窝与NH-1蜂窝性能的对比研究

分别采用国产间位芳纶纸与杜邦T412芳纶纸制作两种规格的蜂窝芯材,并进行了主要力学性能的对比分析。结果表明,国产间位芳纶纸蜂窝在大部分性能上能够与NH-1蜂窝媲美,基本能够满足用户的使用要求,但在工艺性方面仍需要改进。     

芳纶纸纸基结构性能对蜂窝性能影响关系的研究

本文研究了芳纶纸纸基结构性能如纵横向抗张强度、弹性模量、表面强度与蜂窝芯材的剪切强度、压缩强度、剪切模量、胶条线分离强度的影响关系。结果表明:芳纶纸的抗张强度对蜂窝L向剪切强度、压缩强度影响明显;芳纶纸的弹性模量对蜂窝剪切模量影响明显;芳纶纸的表面强度对蜂窝胶条线分离强度影响明显。通过控制芳纶纸纸基结构的性能能够有效保证蜂窝的主要力学性能。     

国产间位芳纶纸蜂窝吸水率及其对力学性能的影响研究

对苏州芳磊蜂窝复合材料有限公司使用国产芳纶纸制造的3种常见规格的间位芳纶纸蜂窝的吸水率和其对压缩性能的影响进行了试验和分析。结果表明,这3种规格蜂窝的吸水率平均在3.4%左右,与杜邦纸生产的Nomex蜂窝的吸水率一致,低于空客的指标值,与吸水前的压缩强度相比,吸水后的压缩强度保持率平均为92%,性能值完全满足GJB 1874-1994中对飞机结构用芳纶纸基蜂窝芯材规范和SAE AMS3711E Core,Honeycomb,Fibrous,Aramid Base,Phenolic Coated对蜂窝湿态压缩强度的要求。     

凯芙拉N636纸制蜂窝结构

据美国加利福尼亚州El Monte市的M．CGLL公司宣称，它们公司的Gillcore ^TM HK蜂窝芯材，适合于波音BMS8．124材料的技术要求，并计划用在波音787飞机上。     

Full characterization for material constants of a promising KNN-based lead-free piezoelectric ceramic

Potassium-sodium niobate (K_1-xNa_xNbO₃, referred to as KNN) solid solutions, which are an important type of lead-free piezoelectric materials possessing environmentally friendly features, good piezoelectric response and high Curie temperature, have attracted considerable attention in replacing lead-based ceramics. In order to promote the application of KNN-based ceramics in piezoelectric devices, we characterized a complete set of material constants of a high performance KNN-based ceramic, that is 0.965(K_0.48Na_0.52) (Nb_0.96Sb_0.04)O₃-0.035Bi_0.5Na_0.5Zr_0.15Hf_0.75O₃ (KNNS-BNZH), whose Curie temperature is 235 °C, piezoelectric coefficient d₃₃ is 380 pC/N and electromechanical coupling factor k₃₃ is 70%. These results will benefit the design of piezoelectric transducers and actuators using lead-free piezoelectric ceramics.     

Mechanical,dielectric, and thermal properties of fluorosilicone rubber composites filled with silica/multiwall carbon nanotube hybrid fillers

In this work, hybrid fillers consist of modified silica (SiO₂) and multiwalled carbon nanotube (MWCNT) were used to improve the mechanical, dielectric, and thermal properties of fluorosilicone (FSR) composites via a direct mechanical mixing method. With the increase of CNT loading in SiO₂/CNT hybrid loading ratio, the tensile properties, dielectric constant, electrical conductivity, and thermal properties all increase without a sharp sacrifice of flexibility. The dielectric constant of FSR-S15/C5 achieved 7,370 @1 kHz, which is about four orders of the FSR-S20, and the dielectric loss remains as low as 0.676 @1 kHz. Therefore, the linkage of SiO₂ and FSR chains not only enhances the interfacial interaction between the fillers and FSR matrix but also decreases the agglomeration of the fillers in matrix. What is more, modified SiO₂ and CNT were designed as the effective hybrid filler to improve the performance of the polymeric matrix through synergic effect.     

Investigation of dielectric and piezoelectric properties in aliovalent Eu3+-modified Pb(Mg1/3Nb2/3)O3-PbTiO3 ceramics

Rare earth (Eu³⁺)-modified Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) polycrystalline ferroelectric ceramics were fabricated by high-temperature solid-state sintering, the phase structure, dielectric and piezoelectric properties were investigated. Eu³⁺ addition was found to significantly improve dielectric and piezoelectric properties of PMN-PT, where the optimized properties were achieved for the composition of 2.5 mol%Eu: 0.72PMN-0.28PT, with the piezoelectric d₃₃ = 1420 pC/N, dielectric ε_r = 12 200 and electromechanical k₃₃ = 0.78, respectively. All these results indicate that the Eu³⁺-doped PMN-PT ceramics are promising candidates for high-performance room-temperature piezoelectric devices.     

High magnetic and ferroelectric properties of BZT-LSM multiferroic composites at room temperature

In this research, the effects of La_0.7Sr_0.3MnO₃ additive on the phase evolution, microstructure, dielectric, ferroelectric and magnetic properties of BaZr_0.07Ti_0.93O₃ ceramics were systematically investigated. The (BaZr_0.07Ti_0.93O₃)/x(La_0.7Sr_0.3MnO₃) or BZT/xLSM (where x?=?0, 5, 10 and 20?mol%) ceramics were prepared via a solid state reaction method. A pure perovskite phase is observed for the samples of x?≤?10?mol%. The M-H hysteresis loops also show an improvement in the magnetic behavior for higher LSM content samples as well as the modified ferroelectric properties. However, the 5?mol% sample exhibited the optimum ferroelectric and ferromagnetic properties with remnant magnetization (M_r) and remanent polarization (P_r) of 2.38?emu/g and 10.5?µC/cm², respectively. The dielectric-temperature curves show that the two phase-transition temperatures as observed for the unmodified BZT ceramic merges into a single phase-transition temperature for the 5?mol% sample and then become flat curves for the 10?mol% sample. In addition, the mechanical properties i.e. Knoop hardness and Young's modulus values increase with increasing LSM content, where Knoop hardness and Young's modulus values for the 20?mol% sample are increased by ~ 45% and ~ 104%, respectively, as compared to the unmodified sample.     

PVDF piezoelectric voltage coefficient in situ measurements as a function of applied stress

Direct piezoelectric g₃₁ voltage coefficient was measured in situ as a function of applied tensile stress for films of polyvinylidene fluoride (PVDF). Measurements were performed under quasi‐static conditions with applied strain rates of 0.5–1.5 mm/min for strains up to 12%. Open‐circuit voltage was measured with a contact‐less electrostatic voltmeter. Obtained results show a strong dependence of the g₃₁ coefficient of mono‐oriented PVDF films on the applied stress, with a maximum value of the coefficient in the transition region between elastic and plastic deformation zones. The effect of sample geometry on the apparent g₃₁ coefficient is shown and discussed. The anisotropy of the piezoelectric effect is studied by means of g₃₁ and g₃₂ measurements. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43248.     

A methacrylate monomer bearing nitro,aryl, and hydroxyl side groups: Homopolymerization,characterization, dielectric,and thermal degradation behaviors

2‐Hydroxy‐3‐(4‐nitrophenoxy)propyl methacrylate (HNPPMA) monomer was synthesized. The poly(HNPPMA) was prepared by free radical polymerization (FRP) method. The characterization of poly(HNPPMA) was carried out using FT‐IR, NMR, differential scanning calorimetry, and GPC techniques. The thermal stability and degradation behavior of this polymer have been studied by using thermogravimetry (TG), GC‐MS, NMR, and FT‐IR. The results were in comparison to poly[2‐hydroxy‐3‐(1‐naphtyloxy)propyl methacrylate] sample with α‐naphtyloxy side group prepared by the same method in the our previous study. The effect of thermal activation on non‐isothermal decomposition kinetics of poly(HNPPMA) was investigated using thermogravimetric analysis according to Flynn‐Wall‐Ozawa method. The dielectric measurements of poly(HNPPMA) and doped with europium(III)chloride (EuCI₃) were investigated by impedance analyzer technique in range of 10–4000 Hz frequency by depending on the alternating current conductivities. The mode of thermal degradation including formation of the main products of poly(HNPPMA) degraded from ambient temperature to 500 °C was identified. S°, the cold ring fraction (CRF) was collected from room temperature to 500 °C. The structure of the degradation products has also been studied depending on the GC‐MS analysis. The thermal degradation mechanism for poly(HNPPMA) with radical degradation processes thought to dominate at high temperature was proposed based on GC/MS, NMR, FT‐IR, and taking into account the new products and differences in stability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43925.     

Metallopolymers based on a polyazomethine ligand containing rigid oxadiazole and flexible tetramethyldisiloxane units

Soluble, easily processable polymer–metal complexes with improved optical and dielectric properties for optoelectronic functional materials were obtained. For this, a new polyazomethine (PAZ2) was prepared by the reaction of a siloxane dialdehyde and bis(formyl‐p‐phenoxymethyl) tetramethyldisiloxane with 2,5‐bis(p‐aminophenyl)‐1,3,4‐oxadiazole, and it was used as a ligand for Cu(II), Co(II), and Zn(II) ions on the basis of the presence of the electron‐donor nitrogen atoms from the azomethine group and oxadiazole ring. The structure of the PAZ2 was determined by spectral [Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy] techniques. The metal complexation was proven by FTIR spectroscopy, and the silicon‐to‐metal ratios in the complexes were established by energy‐dispersive X‐ray fluorescence. The new materials were characterized by gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. The optical properties of PAZ2 and the derived metal complexes were studied by ultraviolet–visible and fluorescence spectroscopies. PAZ2 shows fluorescence emission, and it was significantly enhanced by metal complexation. The emission was enhanced by protonation; this behavior is useful, especially for sensors. The electrical properties were investigated by dielectric spectroscopy at various frequencies and temperatures, and this emphasized the existence of dipolar relaxations. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41631.     

Photoluminescence and unique magnetoluminescence of transparent (Tb1-xYx)3Al5O12 ceramics

Luminescent transparent ceramics (Tb_1-xY_x)₃Al₅O₁₂ (x = 0, 0.2, 0.5, 0.8) are successfully prepared by a solid-state method with additional hot isostatic pressing (HIP) treatment, and the structure and properties are investigated by XRD, SEM, PL, UV–Vis spectrophotometry and ellipsometry. The Y-containing samples are shown to be solid solution phases between TAG and YAG. The PL intensity is 14 times stronger with the incorporation of 80 mol.% Y, and the ⁵D₄→⁷F₅ emission lifetime of Tb³⁺ is prolonged from 0.357 to 3.035 ms at room temperature. A unique magnetoluminescence emerges upon the incorporation of Y, showing an interesting emission decrease to 55% as the Y content reaches 80 mol.%. Remarkably, this magnetoluminesence can occur at room temperature without an intense magnetic field. Based on our work, transparent (Tb_1-xY_x)₃Al₅O₁₂ ceramics exhibit the potential for applications in green emitters, optical instruments and photoelectric devices. In particular, the magnetoluminescence provides a simple, noncontact and nondestructive route for probing magnetic fields.     

The effect of the Zn/Sn ratio on the formation of single phase kesterite Cu2ZnSnS4 solar cell material

The effect of the Zn/Sn ratio in the solution on the properties of Cu₂ZnSnS₄ films prepared by sol-gel method has been investigated. As the Zn/Sn ratio in the solution increases to a certain value, a pure single phase kesterite CZTS is obtained and confirmed by XRD, XPS and Raman. Through controlling the Zn/Sn ratio in the solution, secondary phases such as SnO₂ can be avoided and an optimal condition for single phase kesterite CZTS can be achieved. Surface SEM images of the CZTS films are investigated and the optical band gap of the optimized CZTS film is found to be 1.23 eV.     

Poly[6‐(2,6‐bis(1′‐methylbenzimidazolyl)pyridin‐4‐yloxy)hexyl acrylate] (PBIP) and its terbium (III) complex (PBIP‐Tb3+): Homopolymerization,optical, and magnetic performance

Poly[6‐(2,6‐bis(1′‐methylbenzimidazolyl)pyridin‐4‐yloxy)hexyl acrylate] (PBIP) and its terbium complex (PBIP‐Tb³⁺) were prepared and characterized by ¹H NMR and FT‐IR. The optical properties of PBIP‐Tb³⁺ complex were characterized by UV–vis spectroscopy and fluorescence spectroscopy. Both polymer PBIP and PBIP‐Tb³⁺ complex show good thermal stability. The magnetic property of PBIP‐Tb³⁺ complex was measured as a function of temperature (5–300 K) at 30 kOe and as a function of an external field (?50 to 50 kOe) at 5 K. Magnetic hysteresis loop of PBIP‐Tb³⁺ complex at 5 K shows typical “S” shape and PBIP‐Tb³⁺ complex is soft ferromagnetic. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44249.