棉皮纤维增强聚丁二酸丁二醇酯复合材料的热性能及力学性能研究

采用连续式蒸汽爆破法对棉皮纤维进行预处理,将其与聚丁二酸丁二醇酯(PBS)进行共混,制备了PBS/棉皮纤维复合材料。利用扫描电镜对棉皮纤维及PBS/棉皮纤维复合材料的微观形貌进行了分析,并研究了棉皮纤维含量对PBS/棉皮纤维复合材料熔融及结晶行为、热降解性能、热变形温度以及力学性能的影响。结果表明:经蒸汽爆破处理后,棉皮纤维直径变小,比表面积变大,在PBS基体中分散均匀;棉皮纤维的存在改变了PBS的熔融峰值温度,提高了其结晶度;与纯PBS相比,PBS/棉皮纤维复合材料在高温条件下的热稳定性得到改善维,卡软化温度和弯曲强度提高。     

聚甲基乙撑碳酸酯/聚丁二酸丁二醇酯共混体系性能研究

采用熔融共混法制备了聚甲基乙撑碳酸酯/聚丁二酸丁二醇酯(PPC/PBS)复合材料,通过力学性能、DSC、TG研究了PBS用量对PPC/PBS共混体系力学性能、结晶性能、热稳定性的影响。结果表明:PBS的加入提高了PPC/PBS共混体系的拉伸强度、缺口冲击强度和热稳定性。     

碳酸钙/聚丁二酸丁二醇酯(PBS)可降解复合材料的力学及结晶性能

以生物降解塑料聚丁二酸丁二醇酯(PBS)为基材,以表面改性的CaCO3为填料制备出具有较好注塑性能的碳酸钙(CaCO3)/聚丁二酸丁二醇酯(PBS)可降解高填充复合材料。研究结果表明:改性剂的复配技术可以明显将复合材料的拉伸强度从30.39MPa提高至42.12MPa,复合材料的弹性模量也从1417MPa提高至1614MPa,分别提高了38.6%和14.0%。并通过对不同质量分数CaCO3的复合材料力学性能和热力学性能的研究与分析,为复合材料在不同领域的应用奠定一定的基础。通过对CaCO3/PBS复合材料的结晶性能研究发现,CaCO3在PBS中有一定的成核作用,在一定范围内随着CaCO3添加量的增加,能够促进PBS的成核结晶,明显提高结晶速度、结晶温度和结晶度,减小球晶尺寸,提高材料的拉伸强度。     

花生壳提取物及其复合材料的制备与性能

利用响应曲面法的中心组合设计优化超声提取花生壳中黄酮类物质的提取工艺,建立了提取率与提取时间、提取温度、旋蒸温度、液固比的二次多元回归模型。结果表明,当提取时间为1.5 h,提取温度为50℃,旋蒸温度为50℃,液固比为15,在此条件下的提取率最高可达8.05%。将所得提取物与可生物降解材料聚丁二酸丁二酯(PBS)共混制备复合材料,研究了提取物对复合材料结晶性能、热性能、力学性能的影响。结果表明,花生壳提取物的添加改变了PBS的晶型,增强了PBS材料的热稳定性,但使得复合材料的力学性能下降;花生壳提取物添加比例较大时还可起到成核剂的作用。     

秸秆纤维对PBS复合材料的性能影响研究

采用秸秆纤维对聚丁二酸丁二醇酯(PBS)进行改性,利用热压工艺得到了PBS/秸秆纤维复合材料;研究了秸秆纤维的添加量、处理工艺、偶联剂种类及添加量对PBS/秸秆纤维复合材料力学性能的影响;采用扫描电子显微镜观察了PBS/秸秆纤维复合材料的断裂面形貌.研究结果表明:采用质量分数为1.5%的壳聚糖作为偶联剂,得到的PBS/秸秆纤维复合材料的力学性能最好.     

PBS不同化学结构共聚物的性能

采用改变原料的组分合成不同化学结构的聚丁二酸丁二醇酯(PBS)改性共聚物:聚丁二酸丁二醇/己二酸丁二醇酯(PBS-co-BA)、聚丁二酸丁二醇酯/聚丁二酸乙二醇酯(PBS-co-ES)、聚丁二酸丁二醇酯/聚丁二酸己二醇酯(PBS-co-HS),利用FT-IR和1H-NMR表征共聚物的化学结构,并对共聚物的结构与物理性能、降解性能的关系进行对比.研究结果表明:所有共聚物的结晶度、熔点较其均聚物有所降低;但所有共聚物的断裂伸长率都有所提高.热分析结果表明:PBS-co-HS热性能有所提高,PBS-co-BA和PBS-co-ES有所下降.堆肥降解实验表明:所有共聚物的降解性都比均聚物有显著提高,其降解速度大小顺序为:PBS-co-BA>PBS-co-HS>PBS-co-ES>PBS,PBS-co-HS是综合性能最优良的材料.     

聚丁二酸丁二醇酯纳米复合材料研究进展

综述了聚丁二酸丁二醇酯(PBS)纳米复合改性的研究进展,介绍了纳米复合改性后其摩尔质量、结晶性能、力学性能、热稳定性能及降解性能的变化。PBS通过纳米复合改性后,其摩尔质量有所改变,结晶温度有所提高、结晶速率增大、结晶度降低,而其熔点基本保持不变,同时,其力学性能、热稳定性能和降解的可控性得到了较大的提高。也对PBS纳米复合材料的进一步研究进行了展望。     

PBS/蒲草纤维复合材料的制备与性能

用蒸汽爆破后的蒲草纤维与聚丁二酸丁二醇酯(PBS)制备复合材料,研究蒲草纤维的质量分数对复合材料力学性能、热学性能以及流变性能的影响。研究结果表明:随着蒲草纤维组分的增加,复合材料的弯曲强度和弯曲模量有明显提高,而冲击强度呈现先增大后减小的趋势,当蒲草纤维质量分数为5%时,冲击强度达到最大值5.49 k J/m2。热重分析结果表明蒲草纤维与PBS基体间存在互补作用使复合材料在高温条件下的热稳定性提高。DSC结果表明:随着蒲草纤维质量分数的增加,复合材料的结晶度和熔融温度都呈现增大趋势。平板流变结果表明:蒲草纤维降低了PBS分子的运动能力,增加了复合材料的黏度。     

秸秆纤维的改性对PBS复合材料性能的影响

采用改性剂改性后的玉米秸秆纤维增强聚丁二酸丁二醇酯(PBS),利用热压工艺得到了秸秆纤维/PBS复合材料;研究了苯甲酸、硬脂酸、硅烷、壳聚糖及乙酸5种改性剂对经超声波处理后的秸秆纤维/PBS复合材料性能的影响;采用EDS、SEM、FTIR及WXRD对改性前后的纤维及复合材料进行了分析.研究结果表明:5种改性剂对纤维均有改性效果,苯甲酸质量分数为2%-3%时,复合材料力学性能最优.     

PBS对两种新型聚乳酸复合材料性能的影响

分别以聚乳酸、聚丁二酸丁二醇酯(简称:PBS)及聚乳酸、聚丁二酸丁二醇酯与改性凹凸棒石黏土为原料,制备出两种新型复合材料。考察了不同PBS含量对这两种新型复合材料力学性能与热学性能的影响。结果表明:PBS的加入量越多,拉伸强度、断裂伸长率变化趋势相似,冲击强度与热变形温度变化趋势略有不同。形温度变化趋势略有不同。     

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.