柠檬酸三正丁酯与三醋酸甘油酯增塑醋酸纤维素的研究

研究了柠檬酸三正丁酯（TBC）、三醋酸甘油酯（GT）及增塑剂含量为25%的复合增塑体系中不同GT含量对醋酸纤维素（CA）)流变性能和力学性能的影响。结果表明，随着添加量的增加，TBC和GT都能提高CA的熔体流动谏率。在添加量为25%的时候，GT和TBC单独增塑CA的熔体流动速率分别为5. 42 g/ （10 min）和0.060 g/（10 min）；添加25%的含有20%GT与80%的TBC复合增塑剂增塑CA的冲击强度和熔体流动速率分 别为9.2 kJ/m2和3.63 g/（10 min），能够获得较好的综合性能。     

离子液体[bmim]PF_6对聚乳酸的增塑作用

合成了离子液体[bmim]PF6(1-丁基-3-甲基咪唑六氟磷酸盐),并对其进行了表征。用TG、DSC和偏光显微镜等手段研究了[bmim]PF6对聚乳酸的增塑作用,并比较了它与聚乙二醇300(PEG300)的增塑效果。热重分析结果表明,PEG300作增塑剂时,由于其热降解温度较低,聚乳酸热稳定性变差;离子液体[bmim]PF6作增塑剂时,由于其热失重温度高于聚乳酸热降解温度,用其增塑的聚乳酸热稳定性变好。当[bmim]PF6的质量分数从2%增加到10%时,聚乳酸材料的玻璃化转变温度(Tg)随之降低,当加入质量分数为10%的[bmim]PF6时,聚乳酸材料的Tg降至40℃。偏光显微镜观察看出,加入[bmim]PF6后聚乳酸分子链段的活动能力增强,促进了聚乳酸的结晶,且随其用量增加,结晶度增加。该文报道工作的新颖性,已为教育部科技查新工作站(Z12)于2008年2月26日出具的第ZDT2008017号《科技查新报告》所证实。     

增塑聚乳酸性能的研究

采用熔融共混的方法制备增塑聚乳酸,研究不同增塑剂对聚乳酸力学性能、流变性能、结晶性能以及降解性能的影响.结果表明:增塑剂品种不同对聚乳酸的增塑效果不同,其中三醋酸甘油酯的增塑效果最好;增塑聚乳酸的表观黏度随着剪切速率的增大而下降,改善了聚乳酸的加工性能;增塑聚乳酸的结晶速率加快,片晶厚度减小;增塑聚乳酸的降解速率加快.     

TBC复配增塑对聚氯乙烯防水卷材性能影响的研究

探讨了邻苯二甲酸二辛酯(DOP)和柠檬酸三丁酯(TBC)两种增塑剂对聚氯乙烯(PVC)防水卷材拉伸性能、撕裂性能、尺寸稳定性及增塑剂迁移率的影响。结果表明:在同等增塑剂用量的情况下,TBC增塑体系的力学性能优于DOP增塑体系,但尺寸稳定性和增塑剂迁移率较差。随着TBC/DOP复配体系中TBC含量的增加,PVC防水卷材的断裂伸长率、撕裂强度和尺寸稳定性均呈先增大后减小的趋势,而拉伸强度呈先增大后减小再增大的趋势,增塑剂迁移率呈增大趋势。当TBC/DOP以1:3复配时,PVC防水卷材的拉伸性能、撕裂性能、尺寸稳定性及增塑剂迁移率总体比较理想,均能满足GB/T 12592—2011的要求。     

聚乳酸/聚氧乙烯-聚氧丙烯醚嵌段共聚物共混体系的性能

采用熔融共混制备聚氧乙烯–聚氧丙烯醚嵌段共聚物增塑聚乳酸,研究聚氧乙烯–聚氧丙烯醚嵌段共聚物用量对聚乳酸/聚氧乙烯–聚氧丙烯醚嵌段共聚物共混体系流变性能、力学性能、热性能和微观结构的影响。当添加聚氧乙烯–聚氧丙烯醚嵌段共聚物的质量分数为20%时,聚乳酸/聚氧乙烯–聚氧丙烯醚嵌段共聚物共混体系的熔体流动速率为15.6g/(10min),比未增塑时提高约9倍,断裂伸长率为341.86%,撕裂强度为23.7N/cm,拉伸强度为44.5MPa,玻璃化转变温度从纯聚乳酸的60.1℃降到26.9℃。随着聚氧乙烯–聚氧丙烯醚嵌段共聚物用量的增加,共混体系的拉伸强度先下降后升高,断裂伸长率呈上升趋势,撕裂强度先下降后上升最后渐趋于稳定,聚乳酸链段的活动能力增强,增塑效果明显。扫描电子显微镜分析表明,当聚氧乙烯–聚氧丙烯醚嵌段共聚物质量分数≥12%时,共混体系脆冷断面的褶皱、粗糙度和裂纹明显增加,吸收能量能力增强,表现为断裂伸长率和撕裂强度提高。     

橡胶含量及加工条件对HIPS/PS/PB-g-PS共混物性能的影响

用乳液聚合以CHP-FeSO4为引发体系合成PB-g-PS接枝粉料,与商业高抗冲聚苯乙烯(HIPS)和聚苯乙烯(PS)共混制备HIPS/PS/PB-g-PS舍金.当HIPS的质量分数为10%,PB-g-PS的加入量为15%时体系发生脆韧转变.当HIPS质量分数为10%,橡胶加入量为15%时,体系的冲击强度随挤出机转数的增加而变大.扫描电镜(SEM)研究表明:挤出机转数低加工时剪切强度不够,体系的相容性不好导致脆性断裂.     

聚乳酸/田菁胶共混体系的加工流变性能研究

为了提高聚乳酸的黏度并降低其加工成本,采用田菁胶对聚乳酸进行共混改性。利用转矩流变仪对聚乳酸/田菁胶共混体系的加工流变性能进行研究,讨论了7种增塑剂(甘油、聚乙二醇4000、聚乙二醇6000、聚乙二醇10000、聚乙二醇20000、柠檬酸三丁酯和磷酸三苯酯)及其用量对共混体系加工流变性能的影响。结果表明,甘油的增塑效果不好,扭矩–时间曲线上并没有出现明显的塑化峰。当增塑剂用量为10~15份时,其它6种增塑剂均具有较好的增塑效果。以聚乙二醇6000增塑体系为例讨论了加工条件(加工温度和转速)对体系加工流变性能的影响。发现提高加工温度和转矩流变仪转速可以在一定程度上加快聚乳酸/田菁胶共混体系的塑化。需根据所用加工设备和工艺合理地选择增塑剂种类及其用量和加工条件。     

聚乙二醇增塑聚乳酸复合薄膜的制备与性能研究

通过溶液共混法,以三氯甲烷为溶剂,分别以聚乙二醇200(PEG200)和聚乙二醇1000(PEG1000)作为增塑剂制备了PEG增塑的聚乳酸复合薄膜。通过机械拉伸、热重、XRD和DSC对复合薄膜的力学性能、热稳定性以及热性能进行了表征。结果表明:PEG的加入能有效增强聚乳酸的柔性,断裂伸长率随PEG含量的增大明显升高,拉伸强度则随之降低,且少量添加时PEG200比PEG1000的增塑效率更高;增塑的聚乳酸薄膜低温热稳定性下降,冷结晶温度(t_c)和熔融温度(t_m)降低,结晶能力大幅提高,添加量为15%(质量分数)时PEG200和PEG1000增塑的聚乳酸薄膜结晶度(X_c)分别达到41.06%和50.15%。     

GL/ChCl-GL复配增塑PVA体系的流变行为研究

在聚乙烯醇(PVA)树脂中加入不同含量的甘油/氯化胆碱-甘油(GL/ChCl-GL)复配增塑剂,制备系列GL/ChCl-GL增塑PVA树脂;采用RH2000毛细管流变仪研究了增塑PVA树脂在不同温度和不同剪切速率(■)下的流变行为。结果表明:在■为0～3 000 s~(-1)时,GL/ChCl-GL增塑PVA体系的表观黏度随■的增加而下降,该体系为假塑性流体;随着GL/ChCl-GL含量、温度及■的增加, GL/ChCl-GL增塑PVA体系的非牛顿指数(n)增加,而结构黏度指数(△η)和黏流活化能(E_η)随之降低;当温度为熔点以上25～35℃、■为1 000～2 500 s~(-1)、GL/ChCl-GL质量分数为40%～50%时, GL/ChCl-GL增塑PVA体系的△η和E_η均较小,而n则较高,有利于提高增塑PVA树脂熔融纺丝的稳定性。     

聚乳酸/聚丙二醇增塑体系热性能和流变性能

聚乳酸是一种可完全生物降解的环保材料.研究了聚乳酸/聚丙二醇增塑体系的热性能和流变性能.差示扫描量热仪测试结果表明:随聚丙二醇含量的增加,增塑体系的玻璃化转变温度、结晶温度和熔点均逐渐降低.通过毛细管流变仪测试,发现增塑体系随聚丙二醇含量的增加,熔体指数逐渐增加,表现黏度逐渐降低.聚丙二醇在增塑体系中起到增塑作用,并改善了聚乳酸的加工性能.     

Carbide,nitride and sulfide transition metal-based macrospheres

A general method for the preparation of transition metal carbide, nitride and sulfide composite materials in the form of macroscopic beads is reported. Ti- and W-based materials were prepared by thermal conversion of Ti- or W-loaded ion-exchange resins in an appropriate atmosphere, inert, NH₃ or H₂S, respectively. The spherical macroscopic shape of the resin was preserved in most of the product composite materials. The fabrication of pure TiN spherical macrostructures is also demonstrated by using TiO₂ spherical beads prepared from the Ti-loaded resin by resin oxidation at 600 °C in the thermal treatment procedure.     

Kinetics of anatase transition to rutile TiO2 from titanium dioxide precursor powders synthesized by a sol-gel process

Kinetics of anatase transition to rutile TiO₂ from titanium dioxide precursor powders synthesized by a sol-gel process have been studied using differential thermal analysis (DTA), X-ray diffraction, transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED) and high resolution TEM (HRTEM). The DTA result shows residual organic matter decomposed at 436 K. The transition temperature for amorphous precursor powders converted to anatase TiO₂ occurred at 739 K. Moreover, the full anatase transition to rutile TiO₂ occurred at 1001 K. The activation energy of anatase TiO₂ formation was 128.9 kJ/mol. On the other hand, the activation energy of anatase transition to rutile TiO₂ was 328.4 kJ/mol. Mesoporous structures can be observed in the TEM image.     

The adhesion of amorphous polystyrene surfaces below Tg

The bonding of polystyrene (PS) surfaces below T_g was investigated by two different fracture tests: the lap-shear joint method and the cantilever beam method. Adhesion energy values obtained by the two methods are in agreement and develop with (time)^1/2, at temperatures as low as T_g−16 °C. Even if the double cantilever method is the most common test found in the literature for adhesions above T_g, for low adhesion values, below T_g, the lap-shear joint geometry is more appropriate. Moreover, when the glass transition temperature is used as a reference temperature, polydisperse and monodisperse PS adhesion energy curves are superposable, suggesting that the auto-adhesion is not significantly favored by the presence of numerous chain ends at the surface (due to the low molecular weight chains provided by the polydisperse PS).     

Synthesis and magnetic properties of complex oxides La0.67Sr0.33MnO3 nanowire arrays

As a new approach of melt-injection-decomposition method, it has been successfully adopted for the synthesis of the complex oxides La_0.67Sr_0.33MnO₃ nanowire arrays. X-ray diffraction studies confirmed the formation of perovskite manganite phase of the sample. Transmission electron microscope and scanning electron microscope characterizations showed a large quantity of one-dimensional nanowires is obtained and the nanowires are continuous, concrete, oriented and rather uniform with an average diameter of 170 nm and length of several tens of micrometers. Magnetic measurements exhibited good ferromagnetic properties at the temperature of 10 K and 300 K respectively. The transition temperature of the complex oxides La_0.67Sr_0.33MnO₃ nanowire arrays is about 350 K, which will endow their great potential applications in magnetoresistance, spintronics or sensor fields at room temperature.     

Interaction of dimethyl methylphosphonate with Nafion in acid and cation modifications

Sorption kinetics and sorption isotherms have been determined for dimethyl methylphosphonate, DMMP, in a perfluoroionomer, Nafion™, in the acid form and as calcium and ferric salts. Nafion is a phase segregated polymer with a fluorocarbon main chain and sulfonic acid terminated fluoroether side chain comprising 33 wt% of the polymer. DMMP swells only the fluoroether region. Under immersion conditions, equilibrium solubilities for all three forms are essentially equal, averaging about 130 wt%. Kinetics are non-Fickian, dominated by relaxation effects, with calcium much slower than the acid form of Nafion, and ferric slower still. Analysis with the Joshi-Astarita model of relaxation coupled diffusion indicates that the effect of cation modification is a more than 200-fold decrease in both diffusion coefficient and relaxation rate. Vapor sorption kinetics is also non-Fickian and dominated by relaxation, frequently involving a series of steps or several maxima at high vapor activity. Additionally, kinetics and, to a lesser extent equilibrium solubilities, are affected by sample history and conditions of sample exposure. The sorption isotherm, for acid Nafion exhibits a rapid concentration increase at vapor activities below 0.2, a low slope at intermediate activities and a rapid increase above activity 0.8. Isotherms for salt modifications are similar but with even lower slope at intermediate activities. Effective diffusion coefficients for acid Nafion, calculated from boundary layer corrected steady state permeabilities combined with the sorption isotherm, exhibit a pronounced rise at a volume fraction of 0.6. A transition in NMR solvent self-diffusion coefficients attributed to the emergence of a new phase segregated structure is reported at the same concentration. When effective diffusion coefficients are converted to solvent self-diffusion coefficients, the values are 30-fold lower than NMR values at low concentrations, taken as a measure of tortuosity, but closely approach NMR values above the transition. The prominence of relaxation controlled sorption kinetics and high degree of tortuosity below the transition suggest that Nafion is a disordered structure of small interspersed fluoroether and fluorocarbon regions, whereas the occurrence of discrete relaxation events, mainly at high activities, is probably associated with larger scale reorganization of the partially coalesced phases above the transition.     

Catalytic Liquefaction of Coal and Refining of Products

Abstract

I have been asked to consider the present state of the art in the catalytic liquefaction of coal and refining of products by catalytic means and to suggest some directions for research and development in this very important area of our energy program. This is a large order, as any review of what has been done and what is known about coal liquefaction will quickly show. Coal liquefaction by catalytic means has a long history and has been prached on a commercial scale in various parts of the world. It has had a profound influence on the processing of petroleum. In developing this subject and trying to discern new directions it is very worthwile to review briefly the history of coal liquefaction by catalysis to determine how we have arrived at the present state. By doing this we can also gain knowledge of the constrains imposed on successful developments in this area. It should therefore be possible to determine dirctions for making the processes simpler amnd easier. If nothing else, it will make our attempts to see new things more efficient. Furthermore, the history of coal liquefaction is very interesting and is worth reviewing for itself.     

Effects of sparger geometry on the mechanism of flow pattern transition in a bubble column

Electrical resistance tomography (ERT) is used to measure void fraction wave characteristics and to identify flow pattern in a bubble column reactor (0.24 m diameter, 2.75 m height). The effects of column pressure and superficial gas velocities for different sparger geometry and for different flow pattern have been investigated. The ERT sensor can distinguish the void fraction disturbances in different flow regimes with a good clarity. The holdup derived from ERT is in good agreement with the hold-up values measured by pressure transmitters. Different flow regimes have been identified based on void fraction properties and wall pressure fluctuations. The spectral analysis of ERT measurements yields quantitative information, such as a characteristic time and a characteristic frequency of void fraction waves, which are closely related to flow structure in the prevailing regime. The experimental observations are compared with the literature.     

磺胺间甲氧嘧啶过渡金属配合物的制备及其表征

以磺胺间甲氧嘧啶原药为原料合成了Co(Ⅱ),Cd(Ⅱ),Cu(Ⅱ),Mn(Ⅱ),Ag(Ⅰ)的配合物。并通过红外光谱,紫外光谱和元素分析对产物的结构进行了表征。实验中发现磺胺间甲氧嘧啶与Cd(Ⅱ),Cu(Ⅱ)的成键模式相同,而Mn(Ⅱ)与Co(Ⅱ)相同。     

Structural and electronic properties of poly(3-thiophen-3-yl-acrylic acid)

This work presents a combined theoretical and experimental study of poly(3-thiophene-3-yl acrylic acid), a new polythiophene derivative soluble in polar solvents. Quantum chemical calculations on small oligomers were performed to propose a structural model for this polymer. Specifically, the minimum energy conformations and the rotational profiles of the different isomeric derivatives constructed for a model system formed by two monomeric units were calculated. The resulting model, which shows head-to-tail polymer linkages and the acrylic acid side group arranged in trans-conformation, were used to predict the π-π^∗ lowest transition energy of an infinite polymer chain. On the other hand, the polymer was prepared by chemical oxidative coupling using anhydrous ferric chloride and subsequent alkaline hydrolysis. The synthetized material, which is soluble in aqueous base and acetone solutions, was characterized by FTIR, ¹H NMR and UV-vis experiments. Both the structural information and electronic properties derived from such experiments are fully consistent with the theoretical model obtained using quantum mechanical calculations.     

The transition to turbulence of buoyant near-critical water jets

Observations of near-critical water jets are reported in the injection Reynolds number range of approximately 300–3000 to characterize their transition to turbulence. Three types of cases are described: (i) subcritical jet injected into subcritical water, (ii) supercritical jet injected into supercritical water, and (iii) supercritical jet injected into subcritical water. In each case, the working pressure was kept above the critical value to eliminate two-phase effects. For cases (i) and (ii), the transition behavior follows well known characteristics with transition to turbulence initially occurring near the tip of the jet with the transition location moving upstream nearer to the nozzle exit with an increase in injection Reynolds number. However, the transition behavior for case (iii) is quite different with significant buoyant effects leading to turbulent behavior at lower Reynolds numbers. Consideration of the pseudocritical region with strongly varying fluid properties, which is established in the mixing region between the jet and the cell fluid, yields an effective Froude number that is useful to elucidate this difference. The effective Froude number incorporates the Prandtl number of the mixing region to account for the large disparity between viscous and thermal length scales.