Violet／blue photoluminescence from CeO2 thin film

CeO2 thin film was fabricated by dual ion beam epitaxial technique. The violet/blue PL at room temperature and lower temperature was observed from the CeO2 thin film. After the analysis of crystal structure and valence in the compound was carried out by the XRD and XPS technique,it was inferred that the origin of CeO2 PL was due to the electrons transition from Ce4f band to O2p band and the defect level to O2p band. And these defects levels were located in the range of 1 eV around Ce4f band.     

Synthesis of higher molecular weight PAN and its copolymers for carbon fibers

Higher molecular weight polyacrylonitrile (PAN) was obtained by the free-radical suspension copolymerization of itaconic acid (IA) and acrylonitrile (AN) which was carried out in DMSO/H₂O using 2,2'-azodiisobutyronitrile (AIBN) as the initiator. The effects of polymerization parameters, such as IA monomer concentration and DMSO/H₂O ratio, on the conversion of polymerization and number-average molecular weight are specially described. The copolymerization reaction rate and the number-average molecular weight of the resultant copolymers decrease with the result of high chain transfer constant of DMSO. For the copolymerization of AN and IA, with the inclusion of the good solvent DMSO, the solution degree of AN in DMSO/H₂O is higher than that in water, as a result, the resulting copolymer pellets range from soft bulk to solid grain, as characterized by the use of SEM. Higher molecular weight P(AN-co-IA) copolymers have a lower initiation of exothermal reaction temperature and wider DSC exothermal peaks compared with PAN homopolymers, which corresponds with the results of an IR study.     

Novel approaches to produce Al2O3– TiC/TiCN– Fecomposite powders directly from ilmenite

Al2O3 –TiC/TiCN–Fe composite powders were successfully prepared directly from ilmenite at 1300–1400℃.The effects of Al/C ratio,sintering atmosphere,and reaction temperature and time on the reaction products were investigated.Results showed that the nitrogen atmosphere was bene cial to the reduction of ilmenite and the formation of Al2O3 –TiC/TiCN–Fe composite powders.When the reaction temperature was between 600 and 1100℃,the intermediate products,TiO2,Ti3O5 and Ti4O7 were found,which changed to TiC or TiCN at higher temperature.Al/C ratio was found to affect the reaction process and synthesis products.When Al addition was 0.5 mol,the Al2O3 phase did not appear.The content of carbon in TiCN rose when the reaction temperature was increased.     

Effect of addition of poly（ethylene glycol） on electrical conductivity of poly（3,4-ethylenedioxythiophene）-poly（styrenesulfonate） hybrid

By mixing various concentrations of poly (ethylene glycol), a series of poly(3,4-ethylenedioxythiophene)-poly(styeenesuffonate) composite thin films were prepared.The electrical conductivity of the PEDOT-PSS/PEG thin films was measured by the four-pcobe method. Experimental results showed that the inclusion of poly(ethylene glycol) influenced the electrical conductivity of PEDOT-PSS film significantly. With the increase of PEG concentrations, the electrical conductivity sharply increased to reach a maximum and then slowly decreased down. Furthermore, the PEG molecular weight and environment temperature also played important roles on the electrical conductivity of PEDOT-PSS/PEG thin films. A good linear relationship was found between in σDC and T^-1/2 within the entire temperature range detected.     

High-efficiency trace Na extraction from crystal quartz ore used for fused silica-——A pretreatment technology

Trace Na sources, extraction dynamics of trace Na, and influences of calcination temperature on quartz lattice, fluid inclusions, and muscovite were studied in detail herein for trace Na extraction from the quartz ore with water leaching at 90℃. Experimental results suggested that the trace Na sources included quartz lattice, fluid inclusions, and muscovite. The extraction rate of the trace Na in quartz ores can reach 31.0wt% after calcination at 900℃ for 5 h and water leaching at 90℃ for 24 h. The extraction process consisting of the dissolution of unfree Na and diffusion of free Na was dominated by calcination temperature. Calcination at 900℃ for 5 h was effective for extraction of the trace Na in fluid inclusions and muscovite. The extraction of the trace Na was mainly affected by the decrepitation of fluid inclusions when the calcination temperature ranged from 400 to 600℃ and by the damage of muscovite when the calcination temperature ranged from 600 to 900℃. Based on the extraction rates at different calcination temperatures, approximately 20.1wt% of the trace Na occurred in fluid inclusions, approximately 10.9wt% existed in muscovite, and 69.0wt% mainly occurred in quartz lattice.     

Comparative study on the corrosion behavior of X52, 3Cr,and 13Cr steel in an O2-H2O-CO2 system:products,reaction kinetics,and pitting sensitivity

The corrosion behaviors of X52, 3Cr low-alloy steel, and 13Cr stainless steel were investigated in an O₂-H₂O-CO₂ environment at various temperatures and O₂-CO₂ partial-pressure ratios. The results showed that the corrosion rates of X52, 3Cr, and 13Cr steels increased with increasing temperature. The corrosion rates slowly increased at temperatures less than 100℃ and increased sharply when the temperature exceeded 100℃. In the absence of O₂, X52, 3Cr, and 13Cr exhibited uniform corrosion morphology and FeCO₃ was the main corrosion product. When O₂ was introduced into the system, various forms of Fe₂O₃ appeared on the surface of the samples. The Cr content strongly influenced the corrosion resistance. The 3Cr steel with a low Cr content was more sensitive to pitting than the X52 or 13Cr steel. Thus, pitting occurred on the surface of 3Cr when 1.25 MPa of O₂ was added; this phenomenon is related to the non-uniform distribution of Cr in 3Cr.     

Hot ductility behavior of a Fe-0.3C-9Mn-2Al medium Mn steel

The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical simulator.Hot tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rate of 4×10^?3s^?1.The fracture behavior and mechanism of hot ductility evolution were discussed.Results showed that the hot ductility decreased as the temperature was decreased from 1000℃.The reduction of area(RA)decreased rapidly in the specimens tested below 700℃,whereas that in the specimen tested at 650℃was lower than 65%.Mixed brittle-ductile fracture feature is reflected by the coexistence of cleavage step,intergranular facet,and dimple at the surface.The fracture belonged to ductile failure in the specimens tested between 720-1000℃.Large and deep dimples could delay crack propagation.The change in average width of the dimples was in positive proportion with the change in RA.The wide austenite-ferrite intercritical temperature range was crucial for the hot ductility of medium Mn steel.The formation of ferrite film on austenite grain boundaries led to strain concentration.Yield point elongation occurred at the austenite-ferrite intercritical temperature range during the hot tensile test.     

Temperature-sensitive gold-nanotube array membranes modified with poly（N-isopropylacrylamide）

A kind of temperature-sensitive nanotube array membrane was developed by modifying gold-nanotube array membranes with poly（N-isopropylacrylamide） （PNIPAm）. The permeation ability of the mem-branes at different temperatures was investigated using sodium fluorescein and quantum dots as probes. The results showed that the pore diameter of nanotube was changed due to the reversible response of PNIPAm-modified membranes to temperature, and then the permeation ability of the mem-branes was changed. The permeation of fluorescence probes was slow and even almost blocked at 25℃ （below the lower critical solution temperature, LCST）, since PNIPAm formed expanded structures and decreased the pore size. While at 40℃ （above the LCST）, the permeation was increased, since PNIPAm became compact structures and the pore diameter was increased. Furthermore, the permeation ability of the temperature-sensitive nanotube array membranes could be adjusted reversibly and it is possible to use the membranes in nanofluidic devices, nanogates, etc.     

Effect of bromization on the propertises of a series of substituted 1,8,15,22—tetra（2,4—ditertbutylphenoxy） phthalocyanines

A series of 1,8,15,22-tetra(2,4-ditertbutylphen-oxy) phthalocyanines [α-（oAr）4PcM,M1=(H)2,M2=Pd,M3=Cu,M4=Zn,M5=Pb] were synthesized in this study.Each compound was bromized in two kinds of solvent.One is the solvent mixture of 1,1,2-trichloroethane and water,the other is 1,1,2-trichloroethane alone.The effects of solvent,bromine excess added and reaction duration on the bromization reaction were studied.The shift of maximum absorbance wave-length both is solution and in solid thin film was investigated comparatively,discovering that both were bathochromism but the former was more.TG data showed that the temperature of thermal decomposition decreased continuously with the increase of numbers of bromine.Finally,the fragments produced during the bromization of (OAr)4PcPb in 1,1,2-trichloroethane were characterized by GC/MS.Based on the electronic structure,the possible mechanism of decomposition of these compounds was presented and discussed.     

Linking leach chemistry and microbiology of low-grade copper ore bioleaching at different temperatures

The effects of temperature on chalcocite/pyrite oxidation and the microbial population in the bioleaching columns of a low-grade chalcocite ore were investigated in this study. Raffinate from the industrial bioleaching heap was used as an irrigation solution for columns operated at 20, 30, 45, and 60℃. The dissolution of copper and iron were investigated during the bioleaching processes, and the microbial community was revealed by using a high-throughput sequencing method. The genera of Ferroplasma, Acidithiobacillus, Leptospirillum, Acidiplasma, and Sulfobacillus dominated the microbial community, and the column at a higher temperature favored the growth of moderate thermophiles. Even though microbial abundance and activity were highest at 30℃, the column at a higher temperature achieved a much higher Cu leaching efficiency and recovery, which suggested that the promotion of chemical oxidation by elevated temperature dominated the dissolution of Cu. The highest pyrite oxidation percentage was detected at 45℃. Higher temperature resulted in precipitation of jarosite in columns, especially at 60℃. The results gave implications to the optimization of heap bioleaching of secondary copper sulfide in both enhanced chalcocite leaching and acid/iron balance, from the perspective of leaching temperature and affected microbial community and activity.     

催化合成聚降冰片烯-聚(乙烯-co-丙烯)嵌段共聚物

将活性开环易位聚合得到的聚降冰片烯所带的茂钛取代环丁烷末端基转变成烷氧基茂钛,然后在ＡｌＥｔＣｌ２助催剂存在下催化乙烯与丙烯配位共聚合,合成出聚降冰片烯聚（乙烯ｃｏ丙烯）两嵌段共聚物．考察了铝钛比、聚合温度和单体配比对乙丙共聚合的影响,并通过溶剂萃取及１３ＣＮＭＲ分析对聚合产物进行表征．结果表明约３６％的活性聚降冰片烯有效地转换并在助催剂ＡｌＥｔＣｌ２存在下使乙丙共聚合形成嵌段共聚物．低的聚合温度和铝钛比以及高的乙烯单体比有利于增加乙丙共聚物中形成嵌段共聚物比例     

AN/VAC/甲基丙烯磺酸钠三元共聚系统竞聚率的测定

根据该AN/VAC/甲基丙烯磺酸钠三元共聚体系特征,提出了该体系竞聚率测定的系统研究方案.根据竞聚率计算的原理,融汇二元共聚和三元共聚的基础理论,建立通用竞聚率计算数学模型,开发竞聚率计算软件,为非常规三元共聚体系竞聚率测定提供了新途径.     

聚苯撑乙炔共轭聚合物的合成及光电性能

利用钯催化剂Pd(PPh3)2Cl2和相转移催化剂PTC,采用Heck交叉偶联缩聚反应合成了(苯撑乙炔-氰基乙烯苯撑)共聚物(C12-PPE-DCNTB),比较了聚合物的紫外吸收光谱和荧光光谱特征及热稳定性。以ITO为阳极,Ba/Al为阴极,制备了构型为ITO/PEDOT-PSS/MEH-PPV C12-PPE-DCNTB(1/1,m/m)/Ba/Al的本体异质结器件,初步讨论了活性层的光物理特征及器件的光伏性能。     

PET/PHB(40/60)共聚反应和链结构

本文通过溶解性试验、富里埃红外光谱(FT-IR)、热台偏光显微镜、差示扫描量热仪(DSC)、高分辨核磁共振氢谱(′H—NMR)等方法,对 PET/PHB(40/60)共聚合反应历程,反应过程中嵌段性的形成,以及链结构的变化情况进行了研究。结果表明:共聚合反应初期,同时存在着 PET 的酸性裂介,PHB 的均聚,以及 PET 和 PHB 链段之间的缩聚。随共聚合反应的进行,均聚反应减慢,反应初期所形成的 PHB 刚性链段重新打开参加酯交换反应,共聚酯序列结构由嵌段性逐渐向无规性靠近。     

EA/BA/AN/VAC四元共聚物接枝改性天然橡胶的研究

研究了 EA/ BA/ AN/ VAC四元共聚物接枝改性天然橡胶的制备过程中 ,反应温度、引发剂用量、反应时间及单体浓度对接枝聚合反应的影响。结果表明 :采用乳液聚合方法 ,以 KPS/ SHS氧化 -还原体系为引发剂 ,反应温度 6 0～ 70℃ ,引发剂用量1 .3% ,反应时间 2 .5 h为适宜的合成条件。红外光谱证实了接枝共聚物的生成     

海藻酸钠-高岭土/聚丙烯酸-丙烯酰胺吸水树脂的制备及其性能

 目前高吸水性树脂研究较多的是均聚物,但随着其发展,某些产品的不足之处也逐渐凸显出来,如成本太高、强度不够、吸水速率慢、吸水量低、耐盐性能不好、保水性能不好等,可以采用两种或多种单体共聚合,也可采用接枝共聚或添加廉价填料等方法来改善高吸水性树脂的综合性能及降低生产成本。以丙烯酸为单体,海藻酸钠为接枝物,添加高岭土、丙烯酰胺,通过溶液聚合法制备了复合型耐盐高吸水性树脂。研究了海藻酸钠、高岭土、引发剂、交联剂用量对材料耐盐的影响,制备出在蒸馏水、0.9%NaCl中吸水倍率分别达到895g/g、85g/g的样品。研究了海藻酸钠-高岭土/聚丙烯酸-丙烯酰胺共聚制备高吸水树脂的吸水性能。结果表明,以过硫酸钾为引发剂,反应温度65~75℃,丙烯酸中和度为60%,反应时间4h,引发剂用量0.8%~1.2%,高吸水树脂具有较高的吸水能力;随交联剂用量增大,高吸水树脂的吸水能力下降;随反应温度升高、反应时间延长、丙烯酸中和度增大、引发剂用量以及交联剂用量增大、反应单体浓度升高,海藻酸钠-高岭土/聚丙烯酸-丙烯酰胺共聚物高吸水树脂的耐盐性明显增强。采用红外光谱(IR)、扫描电镜(SEM)等方法对产物的内部结构、表面结构进行了表征。     

聚丙烯酸乙酯-g-聚甲基丙烯酸甲酯接枝共聚物的合成

丙烯酸乙酯与2-溴丙烯酸乙酯乳液共聚合制备了聚(丙烯酸乙酯-co-2-溴丙烯酸乙酯)无规共聚物，用该共聚物作为原子转移自由基聚合的大分子引发剂，进行了甲基丙烯酸甲酯的接枝聚合，制备了聚丙烯酸乙酯-g-聚甲基丙烯酸甲酯接枝共聚物。接枝共聚物的分子量随单体转化率的上升而线性增加。     

7-亚甲基-1,4,6-三氧螺[4,4]壬烷的共聚反应

叙述了7-亚甲基-1,4,6-三氧螺[4,4]壬烷与给电子单体醋酸乙烯酯(VA)、受电子单体丙烯酸甲酯(MA)和丙烯腈(AN)的自由基共聚合反应。分析共聚物的红外、核磁共振氢谱和碳谱,确定了共聚物的结构,该螺环单体能与VA很好共聚,共聚物的组成比和产率受温度的影响。当与MA、AN共聚时,投料比影响共聚物产率,而不影响共聚物组成比。通过对CT络合物研究,探讨了共聚反应机理。对取代基影响共聚活性,共聚物结构作了初步研究。     

DMC/AM/AA三元水溶液共聚合(Ⅱ)

以（NH4）2S2O8－NH2CONH2为引发剂，研究了丙烯酸胺（AM）、甲基丙烯酸氧乙基三甲基氯化铵（DMC）和丙烯酸（AA）三元水溶液共聚合反应，考察了聚合温度、原料配比、单体浓度、引发剂用量以及pH值等因素对聚合速率、单体转化率和产物特性粘度的影响。结果表明：当起始单体总浓度为30～40％，PH≤5．0，DMC和AA在原料配比中的含量分别为20～70mol％、0～30mol％时，聚合反应的条件较为适宜。     

羧甲基纤维素接枝丙烯酸复合材料的制备及对Cr(VI)的吸附研究

以过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,采用自由基聚合法使羧甲基纤维素与丙烯酸进行接枝共聚,制备了一种羧甲基纤维素接枝聚丙烯酸Cr(VI)吸附材料,研究了原料配比、pH、溶液浓度、吸附时间和温度对吸附性能的影响。结果表明：羧甲基纤维素与丙烯酸的质量比为3:17、PH=4.5时复合材料表现出最佳吸附性能;吸附时间为2h时,吸附率大于95%。