海泡石物化改性及在热塑性聚合物中的应用

海泡石是一种天然纤维状含水的镁硅酸盐黏土矿物,具有较高的热稳定性、优异的力学性能以及含有丰富的镁、硅等非卤阻燃元素,可作为一种环境友好型阻燃剂或者阻燃协效剂。但通常需要进行活化改性使其功能化才能更好分散于基体中,以增强热塑性聚合物性能。介绍了天然海泡石的多种物化改性方法。综述了海泡石在热塑性聚合物(聚乙烯、聚丙烯、聚乙烯/醋酸乙烯共聚物等)中的应用研究现状,着重论述了海泡石对热塑性聚合物阻燃性能的影响。最后,总结了海泡石填充热塑性聚合物应用中常见的问题并提出了相应的解决方法,进一步展望了未来海泡石增强热塑性聚合物性能的应用方向。

钛植入材料表面生物化改性研究进展

钛植入材料表面生化成分影响植入后生物反应。旨在促进骨整合,对钛植入材料表面进行生物化修饰改性的研究已取得重要进展。该文就参与钛植入材料表面生化改性的天然有机分子种类及其修饰方法研究进展作一综述。

骨植入材料表面生物化改性研究进展

评述了近年对骨植入材料进行表面生物化改性的研究进展.第一部分是简要的概述.第二部分涉及通过物理吸附或化学作用使黏附性蛋白、生物活性肽、生长因子和某些生物分子等结合到骨生物材料表面,以及这些蛋白质与钙磷共同结合到材料表面.第三部分综述了自组装单层(SAMs)和微模型化(Micropattern)技术在骨生物材料表面改性方面的研究现状.

金属络合物激光物化改性研究

利用激光照射掺杂金属络合物的非金属材料,可使被照射过的区域经过敏化处理后,进行化学镀铜、镀镍等,进而形成导电通道,呈现出金属导体的性质,而没有经过激光照射的区域仍然保持原有的非金属特性。实验采用Nd:YAG激光器,经声光调制后,通过动态聚焦系统和二维振镜实现三维扫描,并经过f-theta透镜聚焦到金属络合物表面。通过调制频率1,3,10和20 kHz的激光调制进行对比实验,实现镀铜层厚度11μm以上,镀镍层厚度2μm以上,在同一种材料表面实现了金属和非金属特性共存的状态。

木质素改性方法及其制备碳纤维的应用研究进展

木质素作为自然界最丰富的芳香族化合物,其含碳量达30%~40%,是制备碳纤维的优质原料。然而由于存在非晶态化学结构、低分子量、宽分子量分布和排列不良等特性,其复杂的非均质结构和固有的易絮凝特质需通过改性以克服。本文介绍了木质素的基本结构单元与特征,并在此基础上详细描述了物理混合、化学改性、生物作用等改性过程工艺条件及其对木质素结构及木质素基碳纤维的强度、电化学、过滤、透气等性能影响,并在此基础上对碳纤维在交通建筑、航空航天、生命健康及新能源等领域应用进行了拓展探讨。此外,拓展概述了木质素的定向官能团改性、绿色改性方法及改性过程表达等可行性,为木质素基碳纤维复合材料的进一步研究和开发提供思考,并推动其实现工业化应用。

高分子复合材料在体育器械的应用与性能

在科学技术不断发展的背景下,材料产业作为21世纪人类三大经济支柱产业之一,越来越受到人们的关注。在交叉学科的不断发展下,体育学科与材料学科联系日益密切,其中高分子材料更是应用广泛。该文从高分子材料在体育器械领域中的应用以及其对体育器材性能提高等方面进行分析,并最终对该类材料在体育器材中的未来应用趋势进行了展望。

鱼明胶替代哺乳动物明胶的研究进展

明胶是胶原蛋白变性的产物,在食品、医药等行业具有很好的使用价值。市面上的明胶以哺乳动物明胶为主,然而,因动物源性病毒与宗教文化等问题而限制了其发展。鱼明胶不受以上因素的限制,与哺乳动物明胶有相似的功能特性,具有很好的开发利用价值。然而,鱼明胶的凝胶性和流变性弱于哺乳动物明胶,研究者采取多种方式修饰鱼明胶,以获得所需要的性能。本文阐述鱼明胶与哺乳动物明胶的性质差异,概述鱼明胶改性方法研究进展,为鱼明胶性质的改善提供参考。

Friction and wear behaviors of Nb-Ti-Si-Cr based ultrahigh temperature alloy and its Zr-Y jointly modified silicide coatings

Zr-Y jointly modified silicide coatings were prepared on an Nb-Ti-Si-Cr based ultrahigh temperature alloy by pack cementation process. The wear behaviors of both the base alloy and coatings were comparatively studied at room temperature and 800 ℃ using SiC balls as the counterpart. The Zr-Y jointly modified silicide coating is mainly composed of a thick （Nb,X）Si2 outer layer and a thin （Ti,Nb）5Si4 inner layer. The coatings possess much higher microhardness than the base alloy. The wear rates of both the base alloy and coatings increase with increasing the sliding loads. However, the coatings have much lower wear rates than the base alloy under the same sliding conditions. The coatings have superior anti-friction property, and can provide effective protection for the base alloy at both room temperature and 800 ℃ in air.

Decomposition mechanism of pentlandite during electrochemical bio-oxidation process

Electrochemical measurements were carried out to elucidate decomposition mechanism of pentlandite using modified powder microelectrode with Acidithiobacillus ferrooxidans attached or without on the mineral powder surface.Cyclic voltammetry（CV） results show that at a low potential of about-0.2 V（vs SCE）,the pentlandite was transformed to an intermediated phase like Fe4.5-yNi4.5-xS8-z when Fe and Ni ions were evacuated from mineral lattice;when the potential was changed from-0.2 V to 0.2 V,the unstable violarite（Fe3Ni3S4） and FeNi2S4 were formed which was accompanied by element sulfur formed on the mineral surface;when the potential increased over 0.2 V,the unstable intermediated phase decomposed entirely;at a higher potential of 0.7 V,the evacuated ferrous ion was oxidized to ferric ion.The presence of Acidithiobacillus ferrooxidans made the oxidation peak current increase with initial peak potential negatively moving,and the bacteria also contributed to the sulfur removing from mineral surface,which was demonstrated by the reduction characteristic at potential ranging from-0.75 to-0.5 V.Leaching experiments and electrochemical results show that the solution acidity increasing when pH2 may impede the oxidation process slightly.

Preparation and properties of composite polymer electrolyte modified with nano-size rare earth oxide

Poly（vinylidene fluoride-co-hexafluoropropylene） （PVDF-HFP） based composite polymer electrolyte （CPE） modified with CeO2, La2O3 and Y2O3 nano-rare earth oxides was prepared by phase inversion technique. Physical and chemical properties of the modified CPEs were studied by SEM, TG-DSC and electrochemical methods. The results show that the CPE modified with 10% La2O3 （mass fraction） has the best practical applicability, which indicates that the thermal and electrochemical stability can reach over 400 ℃ and 4.5 V, respectively, and temperature dependence of ionic conductivity follows Vogel-Tamman-Fulcher （VTF） relationship and ionic conductivity at room temperature is up to 3.3 mS/cm. The interfacial resistance Ri reaches a stable value about 557 Ω after 6 d storage.

Improving Interfacial Electrochemistry of LiNi0.5Mn1.5O4 Cathode Coated by Mn3O4

In this work the surface of LiNi0.5Mn1.5O4(LMN)particles is modified by Mn3O4 coating through a simple wet grinding method,the electronic conductivity is significantly improved from 1.53×10^-7 S/cm to 3.15×10^-5 S/cm after 2.6 wt%Mn3O4 coating.The electrochemical test results indicate that Mn3O4 coating dramatically enhances both rate performance and cycling capability(at 55℃)of LNM.Among the samples,2.6 wt%Mn3O4-coated LNM not only exhibits excellent rate capability(a large capacity of 108 m Ah/g at 10 C rate)but also shows 78%capacity retention at 55 ℃ and 1 C rate after 100 cycles.

Enhanced Biological Nutrients Removal in Modified Step-feed Anaerobic/Anoxic/Oxic Process

In order to enhance phosphorus removal in traditional step-feed anoxic/oxic nitrogen removal process,a modified pilot-scale step-feed anaerobic/anoxic/oxic(SFA 2/O) system was developed,which combined a reactor similar to UCT-type configuration and two-stage anoxic/oxic process.The simultaneous nitrogen and phosphorus removal capacities and the potential of denitrifying phosphorus removal,in particular,were investigated with four different feeding patterns using real municipal wastewater.The results showed that the feeding ratios(Q1)in the first stage determined the nutrient removal performance in the SFA 2/O system.The average phosphorus removal efficiency increased from 19.17% to 96.25% as Q1 was gradually increased from run 1 to run 4,but the nitrogen removal efficiency exhibited a different tendency,which attained a maximum 73.61%in run 3 and then decreased to 59.62%in run 4.As a compromise between nitrogen and phosphorus removal,run 3 (Q1=0.45Qtotal) was identified as the optimal and stable case with the maximum anoxic phosphorus uptake rate of 1.58 mg·(g MLSS)-1 ·h-1.The results of batch tests showed that ratio of the anoxic phosphate uptake capacity to the aerobic phosphate uptake capacity increased from 11.96% to 36.85% with the optimal influent feeding ratio to the system in run 3,which demonstrated that the denitrifying polyP accumulating organisms could be accumulated and contributed more to the total phosphorus removal by optimizing the inflow ratio distribution.However,the nitrate recirculation to anoxic zone and influent feeding ratios should be carefully controlled for carbon source saving.

Evolution mechanism of active sites for selective catalytic reduction of NO_(x) with NH_(3) over Fe-ZSM-5 catalysts doped by Ce/Cu

Fe-ZSM-5 catalysts modified by Cu and Ce by aqueous solution ion-exchange and incipient wetness impregnation methods were tested in the selective catalytic reduction of NO_(x) with NH_(3).A variety of characterization techniques(NH_(3)-SCO,BET,XRD,XPS,UV-Vis,NH_(3)-TPD,H_(2)-TPR)were used to explore the changes of the active sites,acid sites and pore structure of the catalyst.It was found that the dispersion of active Cu species and Fe species had great influences on the catalytic activity in the whole catalytic process.The Cu doping into the Fe-ZSM-5 catalyst produced new active species,isolated Cu ions and CuO particles,resulting in the improved low-temperature catalytic activity.However,the NH_(3) oxidation was enhanced,and part of the Fe^(3+)active sites and more Brønsted acidic sites in the catalyst were occupied by Cu species,which causes the decrease of the high-temperature activity.The recovery of hightemperature activity could be attributed to the recovery of active Cu species and Fe species promoted by Ce and the promotion of active species dispersion.The results provide theoretical support for adjusting the active window of Febased SCR catalyst by multi-metal doping.

Comparative Study of the Modification of Coal Tar Pitch for Higher Carbonization Yield and Better Properties

Parent coal tar pitch(CTP)was modified with boric acid(BA),cinnamaldehyde(CMA)and the mixture of BA and CMA,respectively.The parent CTP and three modified CTPs were characterized by elemental analysis,thermogravimetric analysis,Fourier transform infrared(FT-IR)spectroscopy and scanning electron microscopy.The four samples were carbonized at different temperatures and resultant carbonized products were characterized by FT-IR spectroscopy,X-ray diffraction and polarized-light microscopy.The results show that the morphologies and carbonization behaviors of the parent CTP and modified CTPs are quite different.The carbonization yield of the CTP modified with the mixture of BA and CMA is higher than that of CTP modified with BA or CMA only.In addition,the modification of CTP with 7 g of BA and 10 ml of CMA results in an increase in carbonization yield by5.64%.During the pyrolysis of modified CTPs,the dehydration of BA or the distillation of CMA occurs at the temperature lower than 300°C,and methyl and methylene groups of the modified CTPs disappear gradually as temperature rises.Furthermore,the modification of CTP by the mixture of BA and CMA results in more intensive mesophase spheres than other modified CTPs,and the modified CTP is easier to be carbonized to form graphitic carbon.

Physicochemical Features of Phosphorus-Modified ZSM-5 Zeolite and Its Performance on Catalytic Pyrolysis to Produce Ethylene

The physicochemical features of phosphorus-modified ZSM-5 zeolites (SiO2/Al2O3 molar ratio is 25) were characterized by XRD(X-ray diffraction), BET(Brunauer, Emmett and Teller spcific surface area measurement), NH3-TPD(ammonia temperature-programmed desorption) and MASNMR(magic angle spinning nuclear magnetic resonance), and the performance on catalytic pyrolysis to produce ethylene was investigated with a light hydrocarbon fixed bed micro-reactor with n-octane as feed. The results show that the acid site density, acid intensity and hydrothermal stability of ZSM-5 zeolite were improved by phosphorus modification. When P2O5 content in ZSM-5 zeolite is higher than 2.5%, phosphorus modification can prevent ZSM-5 zeolite crystal structure transformation from orthorhombic to monoclinic. In addition, the dealumination of ZSM-5 zeolite framework was moderated by phosphorus modification under high temperature hydrothermal treatment. The results of n-octane pyrolysis on phosphorus-modified ZSM-5 zeolites show that ethylene yields of zeolites with different phosphorus content are almost the same under the same n-octane conversion. However, the modified zeolites with higher pyrolysis activity give lower yield of propene, butene and total olefin than lower pyrolysis activity under the same n-octane conversion.

Selective Adsorption of Sulfur Compounds in Model Gasoline Containing Olefins by Modified Zeolites

The effects of olefins were quantified by measuring the decreased amount of thiophenes removed by modified zeolites with an increasing olefin concentration in model fuels （300 ppm） via fixed-bed adsorption technique at room temperature and atmosphere pressure. The influence of olefins on adsorptive desulfurization of model fuel had been investigated by FT-IR techniques, which revealed that the protons in the zeolites were the sites responsible for the adsorption of olefins. On the CeY zeolite, in the presence of strong hydroxyl species in the zeolites, the adsorbed olefin compounds can attach to the protons molecularly via electrophilic interaction and undergo the opening of the C=C bonds depending on the acidity of the zeolites. The reduced desulfurization performance of CeY zeolite was attributed to the direct occupation of the absorbent＇s active sites by olefins. In contrast to the CeY zeolite, the NiY zeolites were unable to react directly with pure olefins. However the sulfur compounds and olefins adsorbed on the protons may subsequently undergo olefin alkylation reactions, which can block the zeolite pores and then prevent sulfide molecules from having access to super-cages to contact with the metal cations. This work demonstrates also that the NiY zeolites exhibit excellent performance for selective adsorption desulfurization of model fuel containing olefin compounds.

Power production enhancement with polyaniline composite anode in benthic microbial fuel cells

In this study,conductive polymer polyaniline(PANI)is employed to modify the anodes of benthic microbial fuel cells(BMFC).Four electrochemical methods are used to synthesize the polyaniline anodes;the results show that the PANI modification,especially the pulse potential method for PANI synthesis could obviously improve the cell energy output and reduce the anode internal resistance.The anode is modified by PANI doped with Fe or Mn to further improve the BMFC performance.A maximum power density of 17.51 mW/m2 is obtained by PANI-Fe anode BMFC,which is 8.1 times higher than that of control.The PANI-Mn anode BMFC also gives a favorable maximum power density(16.78 mW/m2).Fe or Mn modification has better effect in improving the conductivity of polyaniline,thus improving the energy output of BMFCs.This work applying PANI composite anode into BMFC brings new development prospect and could promote the practical application of BMFC.

Modifi cation of sleep architecture in an animal model of experimental cirrhosis

AIM： To analyze the polygraphic sleep patterns during cirrhosis progression in a rat model by repeated CCh administration. METHODS： Male Wistar rats received three weekly injections of CCl4 for 11 wk, and were analyzed before and during the induction of cirrhosis. Rats were im- planted with electrodes to record their sleep patterns. Polygraph recordings were made weekly over 11 wk for 8 h, during the light period. After a basal recording, rats received three weekly injections of CCl4. Histological confirmation of cirrhosis was performed after 11 wk. RESULTS： The results showed a progressive decrease in total wake time that reached statistical significance from the second week of treatment. In addition, there was an increase in total time of slow wave sleep （SWS）Ⅱ and rapid eye movement sleep （REM sleep） in most of the 11 wk. SWS I showed no significant variations. During the final weeks, a significant increase in REM sleep frequency was also observed. Histological analyses of the livers showed unequivocal signs of cirrhosis. CONCLUSION： These data suggest that hepatic failure produced by CCh administration is capable of modifying the sleep pattern even after only a few doses.

Preparation of Novel Composite from Natural Rubber, Bagasse and Plaster

The sugar cane bagasse was treated with chemical treatment including sodium hydroxide and silane. The characterization of the modified bagasse was achieved with Fourier transform infrared spectroscopy （FTIR）, and scaning electron microscopy （SEM）. Results showed that the presence Si-CH3 group occurred on bagasse surface after chemical modification. In addition, the roughness of the modified bagasse was higher than that of unmodified bagasse due to chemical modification from sodium hydroxide. Two polymer composite types, namely （1） natural rubber NR/sugar cane bagasse and （2） NR/plaster via two-roll mill method, were prepared. The optimum cure （t90） and torque of the NR/plaster increased with increasing plaster loading in composite. In case of NR/bagasse, the tgo of this sample decreased as a function of sugar cane bagasse while torque of this sample increased with increasing sugar cane bagasse. The modulus of the resulting composite increased with increasing both plaster and sugar cane bagasse, but the tensile strength and elongation at break of the composite decreased as a function of both piaster and sugar cane bagasse in composite.

Diester Derivatives from Chemically Modified Waste Cooking Oil as Substitute for Petroleum Based Lubricating Oils

In order to provide a new way for waste cooking oil(WCO) resource utilization, several diester derivatives were obtained from WCO through a three-step chemical modifications, viz.: transesterification, epoxidation and oxirane ring opening with carboxylic acids. The effects of the chain length of side chain groups on the viscosity, acid value, low temperature fluidity, thermo-oxidative stability, tribological properties and surface tension of diester derivatives were investigated. The results showed that increasing the chain length of side chain groups had a positive influence on the viscosity, viscosity index, acid value, pour point, friction coefficient and wear scar diameter along with a negative influence on the oxidation onset temperature, volatile loss, insoluble deposit, maximum non-seizure load and surface tension. These diester derivatives exhibited improved physicochemical and tribological properties that make themselves promising environmentally friendly biolubricant basestocks.