不同酸根离子制备MgO/TiO2对PVC膜性能的影响

采用硫酸镁和氯化镁作为镁源与三氯化钛为钛源,通过水热煅烧法制备氧化镁(MgO)/二氧化钛(TiO2)复合材料,探究不同酸根离子制备的复合材料性能及对聚氯乙烯(PVC)的影响。结果表明,成功制备以硫酸镁为镁源的复合材料(SMT)和以氯化镁为镁源的复合材料(CMT),SMT为球状,CMT为棒状;SMT使得PVC膜的第一阶段热降解温度提高到265℃,热收缩率降低了31%;CMT则使热降解温度提高到270℃,热收缩率降低了37%;加入复合材料后两种PVC膜的力学性能略微下降;经360 h紫外灯照射后,PVC/CMT的拉伸强度上升幅度最大,断裂伸长率下降幅度最小。综合来看,氯化镁作为镁源制备的棒状复合材料对提高PVC性能有较好的效果。     

Developing a radiation shield and investigating the mechanical properties of polyethylene-polyester/CdO bilayer composite

Radiation attenuation and mechanical properties are two key parameters for shielding in space. This study explored the attenuation parameters of cadmium as a popular filler for the shielding of thermal neutrons in the unsaturated polyester (UPS) polymer matrix. The polyester matrix was used for the first time. The composite behavior against gamma radiation (by applying Cs-137 radioisotope, E gamma = 0.662 MeV) was evaluated using the gamma spectrometer. Also, the sample was exposed to neutron radiation by utilizing a²³⁹Pu–Be neutron source. The effect of the composite sample produced with the cadmium filler was also examined when exposed to gamma radiation. Further, the attenuation parameters of the gamma rays were studied. The observations indicated the suitable shielding of this composite for thermal neutrons, such that the half-value layer (HVL) decreased from 7.8 cm in the polyester sample to 0.22 cm in the polyester/10 wt% CdO composite sample. The linear attenuation coefficient of the thermal neutron increased from 0.0888 (cm^-1) in the polyester sample to 3.15 (cm^-1) in the 10 wt% CdO composite sample, thus indicating more than 35-fold improvement in the neutron attenuation. Composite samples were exposed to gamma radiation; contrary to the expectations, the results showed an almost twofold improvement in the attenuation of gamma radiation, as compared to the polyester sample. This composite specimen was coupled to a 2 mm thick linear low-density polyethylene (LLDPE) layer for the better shielding of thermal neutrons. Finally, the composite sample was mechanically reinforced with a silica glass fiber, which enhanced the ultimate tensile strength (UTS) from 39 to 298 MPa. Also, the elongation rate (% E) was raised from 6% in the polyester sample to 10.5% in the polyester/10 wt% CdO- silica glass fiber sample. Thus, the results indicated the production of a strong composite capable of attenuating neutron and gamma radiation. Accordingly, this composite could be considered a reliable option for use as a shield in space missions.     

氰尿酸镧的协同作用及其复合稳定剂的研究

以氰尿酸、硝酸镧、氢氧化钠为原料合成了氰尿酸镧,通过刚果红试纸法研究了氰尿酸镧与硬脂酸钙、硬脂酸锌、季戊四醇、β-二酮对PVC热稳定性的协同作用;以协同作用为依据,合成了3组复合稳定剂,并且研究了这3组稳定剂的热稳定性、变色性。结果表明:氰尿酸镧与硬脂酸钙、硬脂酸锌、季戊四醇之间有明显的协同作用,但与β-二酮协同作用不明显;复合稳定剂a在热稳定性试验中比另外两组效果好,而复合稳定剂c在变色性方面比另外两组效果都好。     

On-orbit and ground testing of space environment interactions with materials

During the past 12 years, a significant number of different materials have been returned to Earth after extended exposure to space in low Earth orbits. The process steps required to conduct on-orbit exposure experiments and a brief historical outline of materials experiments to date will be described. Examples of material degradation, with emphasis on coatings, will be presented using on-orbit and post-flight photographs of spacecraft hardware and flight test specimens. Results of post-flight testing will be compared with test results from ground-based systems.

Oxidation of coatings, darkening of surfaces due to UV-induced chemical bond rearrangement, and displacement of oxygen atoms from pigments due to proton and electron impact, mechanical failure due to thermal cycling, damage due to microscopic particle impact, and multiple bond ruptures due to high-energy charged particles are observed on hardware returned from orbit.

A current materials flight experiment that includes a significant number of coating specimens, along with many other materials, is the Materials International Space Station Experiment (MISSE). MISSE is flying today on-board the International Space Station (ISS) and will be discussed as an example of the current infrastructure available for on-orbit testing.     

Evaluation of CFCC liners with EBC after field testing in a gas turbine

Under the Ceramic Stationary Gas Turbine (CSGT) Program sponsored by the U.S. Department of Energy (DOE), a team led by Solar Turbines Incorporated has successfully designed engines, utilizing silicon carbide/silicon carbide (SiC/SiC) continuous fiber-reinforced ceramic composite (CFCC) combustor liners. Their potential for low NO_x and CO emissions was demonstrated in eight field-engine tests for a total duration of more than 35,000 h. In the first four field tests, the durability of the liners was limited primarily by the long-term stability of SiC in the high steam environment of the gas turbine combustor. Consequently, the need for an environmental barrier coating (EBC) to meet the 30,000-h life goal was recognized. An EBC developed under the National Aeronautics and Space Administration high speed civil transport, enabling propulsion materials program was improved and optimized under the CSGT program and applied on the SiC/SiC liners by United Technologies Research Center (UTRC) from the fifth field test onwards. The evaluation of the EBC on SiC/SiC liners after the fifth field test with 13,937-h at Texaco, Bakersfield, CA, USA is presented in this paper.     

新型六水氯化镁-六水硝酸镁/石墨相氮化碳复合相变材料的制备及其热性能研究

我国青海盐湖镁资源的利用率低,带来严重的资源浪费和环境污染,若将镁盐开发为相变储热材料,则可扩大其应用领域,从而促进镁盐资源的充分利用。针对中低温保温隔热的应用需求,在前期工作基础上,选用MgCl₂·6H₂O-Mg（NO₃）₂·6H₂O（MCH-MNH）质量比为41∶59的共晶盐作为相变材料,为降低其过冷度并提高隔热性能,选用多孔介质石墨相氮化碳（g-C₃N₄,CN）作为支撑材料,制备低热导率的MCH-MNH/CN复合相变材料。先将尿素在550℃高温下煅烧得到多孔的CN,再采用吸附法制备出MCH-MNH/CN复合相变材料,并对复合相变材料的形貌、结构与热性能进行了表征和测量。结果表明,共晶盐相变材料均匀地吸附在CN的微孔结构内,其与CN的复合是一个物理过程,没有发生化学反应;复合相变材料的相变温度为55.2℃,相变焓值为92.7 J/g,几乎没有过冷度,其热导率为0.3 W/（m·K）,仅是共晶盐MCH-MNH的一半,提高了隔热性能。此外,复合相变材料还具有良好的热稳定性,在中低温保温隔热领域具有应用前景。     

Head Space—Solid Phase Micro Extraction Profile of Volatile Organic Compounds Emitted from Parquet Samples

The potential health risks posed by volatile organic compounds (VOCs) in homes are of concern. There is little information on indoor VOC emissions from wood flooring, called parquet. Six parquet samples were examined for VOCs in this preliminary study using Head Space—Solid Phase Micro Extraction (SPME) gas chromatography, a powerful and versatile analytical method which has been only minimally employed previously in wood chemistry. Prefinished composite samples released the highest levels of VOCs, mainly due to adhesives and finishes, with acetic acid the main component released from the oak component. As some VOCs from parquet present a health hazard, more comprehensive studies employing the SPME technique described herein are needed.     

Ni-ZrO2复合电镀工艺的研究

研究了Ni-ZrO2复合镀液体系中微粒与镀液间的相互作用.镀液中的电解质NiSO4和NiCl2对ZrO2纳米微粒在复合镀液中的悬浮稳定性有很大影响.阴极极化曲线表明纳米微粒的加入改变了基质金属电沉积的过程.以高分子聚电解质作为分散剂,利用其在微粒之间形成的空间位阻效应,减弱镀液中离子对微粒的聚沉作用,得到了均匀分散的ZrO2纳米微粒的复合镀镍溶液,并对各种镀层的形貌和硬度进行了分析.     

用于环境净化的TiO2/AC复合材料的制备及其改性研究进展

二氧化钛（TiO₂）在光照下可以产生具有强氧化性能的活性基团,活性炭（AC）具有良好的吸附性能。将TiO₂负载在AC上制备的TiO₂/AC复合材料可以有效去除大部分难降解的有机污染物,因此在环境净化领域具有良好的应用前景。本文综述了TiO₂/AC复合材料的研究现状,介绍了目前TiO₂/AC复合材料的三种主要制备工艺：溶胶-凝胶法、溶剂热法和微波合成法。其中溶胶-凝胶法所制备的材料稳定性好、溶剂热法制备条件温和、微波合成法制备周期短。针对TiO₂/AC复合材料可见光吸收率低和量子利用率低等问题,介绍了离子掺杂、半导体复合、贵金属沉积等现有的TiO₂/AC复合材料改性方法。之后,概述了所制备的TiO₂/AC复合材料在去除难降解有机污染物（染料废水、药物类、酚类、挥发性有机物）中的应用。最后展望了TiO₂/AC复合材料在改性研究与实际应用过程中存在的挑战性问题及可行的解决方法,为TiO₂/AC复合材料深入研究和大规模工业生产应用提供参考。     

木质素/聚烯烃复合材料界面增容的研究进展

木质素作为植物界第二大可再生生物质资源,其有效利用技术一直是人们关注的热点。利用共混技术制备木质素/聚烯烃复合材料不仅可以提高木质素的有效利用率,还可以减少化石能源的消耗,提高聚烯烃的环境适应性,是近年来研究的热门课题。然而聚烯烃和木质素之间的界面黏附能力差,直接影响复合材料的性能,因此改善两者的界面相容性对于提升木质素/聚烯烃复合材料的性能至关重要。本文介绍了木质素的结构与性能,分析了木质素与聚烯烃相容性差的原因,同时从增容方法和共混工艺两方面回顾了国内外在木质素/聚烯烃复合材料界面增容方面的研究现状和最新进展,着重阐述了增容剂种类、木质素改性方法、共混工艺参数的改变对复合材料界面相容性的影响。此外,在木质素/聚烯烃复合材料生产生活应用的基础上展望了木质素/聚烯烃复合材料界面增容的发展趋势,指出进一步寻找成本低廉、性能优异的增容剂,探索更有效的复合增容工艺以及引入能量牺牲键将是未来研究的主要方向。     

Polyaniline/carbon black composite as Pt electrocatalyst supports for methanol oxidation: Synthesis and characterization

Core/shell composites of polyaniline (PANI) and Vulcan XC‐72 Carbon (VC), in which the carbon represents the core and PANI forms the shell, were synthesized by in situ chemical oxidation polymerization. Platinum (Pt) particles were then deposited on the PANI/VC composites by chemical reduction method. The highest conductivity is obtained when a mass ratio of PANI/VC equals to 0.28, as proved by Fourier transform infrared spectra. And it is also proved that there are some reactions happened between PANI and VC. Scanning electron microscope, transmission electron microscope, and X‐ray diffraction measurements were performed to analyze their structure and surface morphology. It has been observed that the Pt particles are smaller in size and more uniformly distributed on these composite supports than on pure VC supports, considered as a reference. Methanol oxidation performed on the electrode modified by such a composite catalyst has been measured by cyclic voltammogram focusing on the attenuation of methanol oxidation current after 200 cycles. The attenuation degree for the composite catalyst is only one‐third of the one measured for a simple Pt/VC catalyst. It is proved that the composite catalyst better resist carbon monoxide poisoning in comparison with the Pt/VC catalyst, which may be due to the synergetic effects between the composite support and the Pt catalyst. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

利用煤矸石制备Fe3O4和Fe负载的微波吸收材料

为了实现固废煤矸石的有效资源化利用,本文利用煤矸石设计合成了负载Fe₃O₄和Fe的陶瓷复合微波吸收材料。实验主要包括煤矸石的造粒成球、液相负载Fe³⁺及焙烧过程,利用X射线衍射仪(XRD)、拉曼光谱仪(Raman)和扫描电镜(SEM)对样品的物相与微观结构进行了分析表征。结果表明,前驱体溶液经过分解反应、碳热还原反应转化为Fe₃O₄和Fe,原位负载于煤矸石基体上,并显现铁磁特性。借助矢量网络分析仪测试样品的电磁参数,基于传输线理论分析评价其微波吸收性能。由于良好的阻抗匹配与衰减特性,复合材料FeG700体现出良好的吸波能力,在涂层厚度为1.5 mm时,最低反射损耗值为-20.1 dB,有效吸收带宽可达4.1 GHz。本研究不仅有助于实现微波吸收材料制备的低成本化,重要的是为固废煤矸石的综合利用提供了借鉴。     

Durability of PBI adhesive bonded joints under various environmental conditions

Structural adhesives are finding increasing use in many applications. However, their utilization at elevated temperature has always been a challenge due to their low thermal and mechanical properties. However, in recent years, the development of high performance polymers have overcome the problem of using adhesive bonding at high temperature to some extent. Polybenizimidazole (PBI) is one such recently emerged high performance polymer with excellent thermal and mechanical properties. It has a tensile strength of 160 MPa and a glass transition temperature (T_g) of 425 °C. Due to its excellent thermal and mechanical properties, it has the potential to be used as an adhesive under various environmental conditions. In the present work, efforts are devoted to explore the potential of using PBI at high temperature and in hot-wet environmental conditions. M21 and DT120 epoxy based carbon fiber composite bonded joints were prepared and tested. Both M21/carbon composite and DT120/carbon composite have exhibited a reduction in joint strength of about 16% and 25% respectively after 1000 h of conditioning in a hot-wet environment. However, a reduction in lap shear strength of 52% and 56% is observed when composite bonded joints were tested at 80 °C.     

Effects of a soft segment component on the physical properties of synthesized waterborne polyurethanes by using triblock ester-ether copolydiol as the soft segment

This paper examines the effect of an ester-ether soft segment structure on the physical properties of synthesized WBPUs. The CET series, CPT series, and CMT series anionic waterborne polyurethane (WBPU) were prepared with PCL-PEG-PCL, PCL-PPG-PCL, and PCL-PTMG-PCL triblock copolydiol as the soft segment. These copolydiols were synthesized from polyethylene glycol (PEG), polypropylene glycol (PPG), or polytetramethylene glycol (PTMG), respectively, by end capping with caprolactone (CL). Particle size and its distribution, solvent absorption, thermal properties, and the mechanical properties of the WBPUs were studied. The particle size of WBPU dispersion was in the sequence of CET > CPT > CMT series. The CET series WBPU had better phase mixing between the soft and hard segment, whereas the CMT series WBPU had good phase separation and better mechanical properties. In addition, both the phase mixing and mechanical properties increased with PCL content, except for the CMT series WBPU.     

AKD改性PETG/废纸粉木塑复合材料制备工艺

为了提高废纸的利用率,保护森林资源,开发绿色无污染的木塑复合材料,使用废弃纸箱和聚对苯二甲酸乙二酯–1,4–环己二甲酯(PETG)作为原料,利用烷基烯酮二聚体(AKD)对其进行改性制备木塑复合材料。选取碱处理浓度、时间、温度和AKD添加量四个方面进行实验,探究对PETG木塑复合材料力学性能、吸水性能和热稳定性的影响,并且结合红外和微观形貌表征,确定了对废纸纤维进行改性的木塑复合材料的最佳工艺为:NaOH溶液浓度15%,碱处理温度60℃,碱处理时间60 min,AKD最佳添加量为废纸粉质量的2%。     

Utilization of Flyash as Filler Material in Hybrid Polyester Composites for Improved Thermo-Mechanical and Erosion Wear Behavior

The present work was carried out for the utilization of major quantities of flyash as filler material in the short fiber reinforced polyester resin composites in various engineering and structural applications. The incorporation of flyash modifies the hardness, tensile, flexural, impact and damping behavior of the composites. It is observed that hardness, flexural modulus and impact strength of flyash filled composites increases with increase in the flyash filler contents. Whereas, with the addition of flyash contents it is observed that there is decrease in tensile strength and flexural strength. But beyond the 10 wt.-% flyash filler addition in the composite the flexural strength increases. At the end, the erosion wear behavior of all the composites has been studied by Taguchi experimental design. It is found that unfilled glass polyester composite suffers greater erosion loss as compare to particulate filled glass polyester composites. The eroded surface morphology is examined by SEM and the related erosion wear mechanism is discussed in detail.     

多向受力状态下复合材料预紧力齿连接接头应力分析

为了探究复合材料空间桁架桥中关键节点预紧力齿连接接头在多向受力状态下的应力分布,对复合材料空间桁架桥建立多尺度有限元模型。该多尺度模型不仅可以同时获得桁架桥整体结构性能与局部接头应力状态,还可以有效反映两者的相互作用关系。通过该模型,对接头在多向受力状态下的应力分布展开研究,研究表明:预紧力齿接头受力之后,齿面正应力较过盈装配完成时有5 MPa以内的衰减;且多向受力接头较单向受力接头衰减缓和,衰减后多向受力接头齿面正应力略高于单向受力接头齿面正应力;多向受力接头各齿荷载分配比例与单向受力基本一致,均为两侧高中间低;多向受力接头复合材料管横向剪切应力较单向受力接头有一定增大,但最不利荷载工况下的横向剪切应力为15.7 MPa,远小于材料横向剪切强度,接头处于安全状态。所得结果可为复合材料预紧力齿接头设计提供参考依据。     

基于电解锰渣-磷石膏复合胶凝材料的制备与表征

为了有效提高电解锰渣资源化利用水平,针对电解锰渣化学成分和矿物组成特点,以电解锰渣为主要原料,通过辅加磷石膏、水泥、矿粉制备胶凝材料;在固定矿粉与水泥掺量的基础上,通过改变磷石膏的掺量,研究不同硫酸盐掺量对复合胶凝材料力学性能的影响。研究结果表明,制备的复合胶凝材料中电解锰渣、磷石膏、矿粉、水泥最佳质量配比为50:20:20:10,其硬化体14 d抗压强度可达20.62 MPa,而软化系数为0.80。电解锰渣-磷石膏复合胶凝材料的水化产物主要是钙矾石、C-S-H、和C-A-S-H。水化14 d后的硬化体浸出液中污染物浓度均在《地表水环境质量标准》(GB 3838—2002)中Ⅴ类水体标准的限值内,其中Cr、Cu、Zn、As、Pb、Cd等重金属浓度可达到Ⅰ类水体的标准,硬化体具有良好的环境稳定性。     

正十八烷/OBC/EG复合定型相变材料制备及热物性

针对正十八烷相变易泄漏的问题,采用烯烃嵌段共聚物（olefin block copolymer,OBC）作为封装结构,制备复合定型相变材料。并通过添加膨胀石墨（expanded graphite,EG）,改善其热导率低的问题。研究结果表明,当OBC的质量分数为20%时,复合相变材料未发现明显泄漏,定型效果较好,此时复合相变材料的相变焓为166.87 J/g,相较纯十八烷（227.40 J/g）下降26.62%。针对添加有不同质量分数EG的复合相变材料,其热导率随EG含量的增加而增大。其中当EG质量分数为5%时,复合相变材料热导率为4.179 W/(m?K),较纯相变材料热导率[0.24 W/(m?K)提高了约16倍,即EG能够有效提高复合相变材料的导热性能。此外,5%含量下的复合相变材料相变焓约为149.54 J/g,且在经历50次循环后,相变温度和相变焓均未有明显变化,即制备的复合相变材料具有较好的热稳定性。因此,该复合相变材料在建筑节能方面具有应用潜力。     

羽毛角蛋白综合开发利用新进展

羽毛角蛋白是家禽加工企业产生的废弃物,直接丢弃不仅浪费了蛋白质资源同时也污染了环境.羽毛角蛋白的开发利用近年来引起了普遍兴趣.本文对羽毛角蛋白的提取及其应用开发研究进展进行了总结评述,指出羽毛角蛋白主要用于动物饲料、可食性包装材料和制备复合材料,也可以与其它单体共聚改性,提高材料的可生物降解性.开发非饲料用高性能羽毛蛋白复合材料和改性材料是今后这方面研究的主要方向.