双马来酰亚胺改性氰酸酯树脂及其复合材料

制备了一种新型的双马来酰亚胺改性氰酸酯树脂以提高这类树脂的耐热性,力学性能及成型工艺性。对合成的树脂作了流变分析,对其玻纤复合材料进行了力学性能测试和热失重分析,结果表明,当双马树脂达到改性氰酸酯树脂的质量分数的37.5%时,新型改性氰酸酯树脂的5%热失重温度为432℃。改性氰酸酯基复合材料在常温条件下的拉伸强度为492.4 MPa,弯曲强度为526.3 MPa。在200℃时改性氰酸酯基复合材料的拉伸强度为357.3 MPa,弯曲强度为292.7 MPa。该树脂具有良好的加工性,耐热性,力学性能及高温力学保持性。     

双马来酰亚胺改性氰酸酯树脂及其复合材料

制备了一种新型的双马来酰亚胺改性氰酸酯树脂以提高这类树脂的耐热性,力学性能及成型工艺性。通过流变分析和热失重分析对合成的树脂进行了研究,对其玻纤复合材料力学性能进行了测试。结果表明,当双马树脂达到改性氰酸酯树脂的质量分数的37.5%时,树脂的5%热失重温度为415℃,复合材料常温下的拉伸强度为438.8MPa,弯曲强度为657.3MPa,断裂伸长率为9.2%;200℃下的数据分别为310.5MPa,307.4MPa,12.5%。该树脂具有良好的加工性,优异的耐热性和力学性能。     

新型双马来酰亚胺改性氰酸酯树脂及其复合材料

采用双马来酰亚胺封端的硫醚酰亚胺低聚物对氰酸酯树脂进行了改性(SBMI),通过红外光谱对改性树脂(SBT)的结构作了表征,通过流变分析,热失重分析研究了其粘度特性及耐热性,并对其玻纤复合材料的力学性能进行了测试。结果表明,当SBMI质量分数为氰酸酯树脂的的37.5%时,SBT树脂的5%热失重温度为415℃,其复合材料在常温下的拉伸强度为438.8 MPa,弯曲强度为657.3 MPa,断裂伸长率为9.2%;200℃时拉伸强度为310.5 MPa,弯曲强度为307.4 MPa,断裂伸长率为12.5%。该树脂具有良好的加工性,耐热性和力学性能。     

湿法缠绕成型T700碳纤维/氰酸酯树脂复合材料力学性能研究

研究了湿法缠绕成型的T700碳纤维/氰酸酯树脂复合材料NOL环及单向板力学性能。测试了树脂配方的粘度-温度特性,T700碳纤维/氰酸酯树脂复合材料NOL环的拉伸及剪切性能,采用SEM对NOL环拉伸试样破坏形貌进行了观察。测试了T700碳纤维/氰酸酯树脂单向板复合材料的常温拉伸性能、弯曲性能、层间剪切性能和高温弯曲性能。结果表明,树脂配方在25℃下的粘度为800 cps,可以直接在室温条件下用于复合材料湿法缠绕成型,并具有充分的使用期。NOL环的拉伸强度为2220 MPa,剪切强度为56. 8 MPa,树脂基体对碳纤维具有良好的浸润性,能够较好地发挥出碳纤维的高强度特性。T700碳纤维氰酸酯树脂单向板复合材料的高温力学性能优异,200℃下弯曲强度保留率高达60. 4%,250℃下弯曲强度保留率高达45. 0%。     

香蕉纤维的表面改性及其增强环氧树脂复合材料的性能研究

采用硅烷偶联剂(A-174)偶联、高锰酸钾接枝和乙酰化包覆等3种方法对香蕉纤维进行表面改性,制备了改性香蕉纤维增强环氧树脂复合材料,测试其拉伸、弯曲、压缩、冲击等力学性能。结果表明,偶联、接枝、包覆等表面改性均能明显改善香蕉纤维与基体树脂的相容性,提高复合材料的力学性能,其中偶联改性的效果最好。当改性香蕉纤维含量为10wt%时,与未改性的香蕉纤维比较,复合材料的拉伸强度、弯曲强度、压缩强度分别提高了1.8、1.0、2.6倍;随着纤维含量的增加,复合材料的力学性能明显提高。     

基于阀体制造的先进树脂基复合材料性能研究

研究了不同改性方法对酚醛团状膜塑料（BMC）、酚醛片状膜塑料（SMC）、乙烯基SMC材料力学性能的影响,分析了树脂基与纤维相的改性作用机制,得到了三者中具有最佳力学性能的复合材料,并通过仿真分析验证了不同复合材料用于制造阀体的可行性。结果表明,3种材料的拉伸性能为乙烯基SMC>酚醛BMC>酚醛SMC,弯曲性能为酚醛BMC>乙烯基SMC>酚醛SMC,乙烯基SMC的综合力学性能最佳;成型温度为160 ℃、模压压力为9 MPa、保温时间为30 min时,乙烯基SMC的拉伸强度、拉伸模量、弯曲强度、弯曲模量分别达到148.26 MPa、4.50 GPa、92.33 MPa、2.39 GPa;阀体静力学分析结果表明,乙烯基SMC与酚醛BMC均满足阀体制造要求。     

液体端羧基丁腈橡胶改性氰酸酯／玻璃纤维复合材料的性能研究

用液体端羧基丁腈橡胶(CTBN)对氰酸酯树脂(CE)进行了增韧改性,通过树脂体系的凝胶时间曲线和DSC曲线确定了体系的固化工艺,并制备了玻璃纤维(GF)增强复合材料。CTBN改性后的CE树脂及复合材料具有良好的力学性能,其中固化树脂的弯曲强度和冲击强度分别提高了34.6%和48%,复合材料的弯曲强度和冲击强度分别提高了11.4%和21.3%,这来源于CTBN对氰酸酯树脂的增韧作用及与GF良好的粘接性能。     

国产高强高模PAN基碳纤维预浸料的制备及性能研究

以国产CNI QM55高强高模聚丙烯腈(PAN)基碳纤维、氰酸酯树脂为原料,利用热熔法制备高强高模PAN基碳纤维预浸料,通过纤维面密度、树脂含量、挥发分含量等来评价预浸料的物理性能,结合单向板的微观形貌与层间剪切强度分析单向板的界面结合性能,并对预浸料铺制单向板的力学性能进行表征。结果表明：CNI QM55碳纤维预浸料的纤维面密度为145 g/m²,树脂质量分数为35.5%,挥发分质量分数为0.164%,预浸料的物理性能满足复合材料的性能要求;以CNI QM55碳纤维预浸料制备的单向板0°拉伸强度为2 429 MPa, 0°拉伸模量为328.4 GPa,弯曲强度为1 171 MPa,弯曲模量为280 GPa,压缩强度为783 MPa,压缩模量为257 GPa,层间剪切强度为65.2 MPa,具有较好的界面黏接性能和力学性能,可满足加工应用要求。     

树脂传递模塑工艺用改性氰酸酯树脂体系研究

由自制改性剂苯乙烯和丙烯酸正丁酯低聚物及TDE-85环氧树脂协同改性氰酸酯树脂,采用示差扫描量热仪,动态热机械分析仪,力学性能和粘度测试研究了改性后的氰酸酯树脂的性能。结果表明,改性氰酸酯树脂浇铸体玻璃化转变温度高于215℃,TDE-85环氧树脂质量分数为15%时,改性氰酸酯树脂浇铸体的综合性能最佳,拉伸强度为45 MPa,弯曲强度为86 MPa,冲击韧性为17 k J/m~2。改性树脂体系室温下6 h内粘度保持在1 000 m Pa·s以下,满足树脂传递模塑成型工艺的要求。     

玄武岩纤维增强高密度聚乙烯的力学性能

玄武岩纤维(BF)未经改性处理和经硅烷偶联剂(KH–550和KH–570)进行处理后,添加到高密度聚乙烯(PE–HD)基体树脂中,增强PE–HD的力学性能,用傅立叶变换红外光谱和扫描电子显微镜对硅烷偶联剂处理的BF进行表征,同时,用SEM观察BF增强PE–HD复合材料的拉伸断面。结果表明,随着未经改性处理BF添加量增加,PE–HD复合材料的拉伸强度、弯曲强度逐渐提高,当添加量达到30%时,拉伸强度达到45.5 MPa,提升79.1%;弯曲强度达到41.3 MPa,提升118.9%。经KH–550和KH–570处理的BF添加量达到20%时,PE–HD复合材料的拉伸强度均达到45 MPa以上,其后随着BF添加量继续增加,拉伸强度变化不大,而弯曲强度随BF添加量的增加逐渐增大。当BF添加量达到30%时,BF改性与否对PE–HD复合材料的力学性能的影响不大。当改性BF添加量为5%~15%时,KH–550改性的PE–HD复合材料的力学性能较KH–570改性的高;当改性BF添加量为20%,25%时,KH–570改性的PE–HD复合材料的力学性能较KH–550改性的高。     

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.