聚丙烯腈／二醋酸纤维素共混体系流变性能的研究

探讨了聚丙烯腈／二醋酸纤维素共混溶剂的选择、体系的相容性和流变性，结果表明，二甲基亚砜是体系的较好溶剂，体系表现出切力变烯性质；并随着二醛纤维素／聚丙烯腈共混比的增加，总固含量的及温度的降低，共混溶液的非牛顿指数降低、结构粘度指数上升，且剪切弹性模量和最大松弛时间增大，为进一步制备聚丙烯腈／二醋酸纤维素膜提供了合适的认为和热呼参数。     

共混法制备高分子固-固相变材料及其表征

通过共混法制备了PEG／CDA高分子固-固相变材料，用DSC差示扫描量热法对其相变行为进行了研究，讨论了PEG／CDA质量比对所得相变材料相变行为的影响。结果表明，该材料呈现出固-固相转变特性；其相变温度和相变焓比纯PEG低，并随着PEG含量的增加而升高。     

PVDF／PES／CA平板式共混超滤膜的研究

研究了致孔剂种类和用量对聚偏氟乙烯（PVDF）／聚醚砜（PES）／二醋酸纤维素（CA）共混平板膜结构和性能的影响，表征了共混超滤膜的水通量、截留率、孔隙率、收缩率和膜的断面形态等。结果表明，添加PES可以提高PVDF膜的尺寸稳定性，而添加1％CA可以提高PVDF／PES共混膜的亲水性，水通量显著增加。当PVDF／PES...     

溴甲酚绿-稀土配合物的热变色性能及变色机理

以稀土金属离子(La3+、Ce3+和Nd3+等)为显色剂,溴甲酚绿为发色剂和配位剂,制备了一系列稀土配合物可逆热变色材料,测试其综合变色性能,讨论了显色剂种类及用量、溶剂用量对稀土配合物热变色性能的影响。FT-IR、UV-Vis和DSC测试结果表明,热变色机理可归结为分子间的电子得失,随着温度变化,溴甲酚绿的结构在内酯式和醌式之间转变,颜色随之改变。     

醋酸纤维素/聚乙烯基亚胺共混微孔滤膜对Cu2+的吸附

以二醋酸纤维素N(CA)／聚乙烯基亚胺(PEI)共混制备微孔滤膜,利用PEI对重金属离子的螯合作用吸附水溶液中的Cu^2 ,实验考察了吸附时间、pH对Cu^2 静态吸附性能的影响．膜对Cu^2 的等温吸附符合Langmuir型吸附,其饱和吸附量取决于膜中PEI的含量．     

聚乙二醇／聚乙烯醇共混物的相变特性与结晶

通过溶液共混法制备了系列PEG4000／PVA共混物，并采用DSC、WAXD、FT-IR等手段对共混体系的相变特性及结晶进行了探讨。结果表明：共混体系具有可逆的固-固相转变特性。共混物的熔点（Tm）基本保持不变，而结晶峰值温度（Tc）与PEG／PVA质量百分含量有关。其相变焓是随着PEG含量的增加而逐渐增加。聚乙烯醇的存在对共混体系中PEG的结晶和熔融过程均有所影响，但共混体系与纯PEG4000具有相同的衍射线、衍射角和面间距，且并未发现新的衍射峰出现。共混体系中x射线衍射峰的半峰宽度大于纯PEG的半峰宽度，说明共混过程使PEG结晶粒子变小。     

左旋聚乳酸/右旋聚乳酸嵌段共聚物的共混物及其纤维的结构与性能

以右旋聚乳酸-聚乙二醇-右旋聚乳酸(PDLA-PEG-PDLA)三嵌段共聚物作为改性剂,通过熔融共混法及熔融纺丝-后牵伸两步法分别制备了左旋聚乳酸(PLLA)/PDLA-PEG-PDLA共混物及其共混纤维。采用差示扫描量热分析、热重分析、毛细管流变仪、扫描电镜、广角X射线衍射及力学性能测试等方法对共混物及其共混纤维的结晶行为、热性能、取向及力学性能等进行了研究。结果表明,熔融温度对PLLA及其共混物的结晶行为有较大的影响。当熔融温度为230℃时,共混物中PDLA-PEG-PDLA含量为10%时,α晶的结晶温度最高,为127℃;另外,共混物具有较好的纺丝性能,相同条件下制备的共混纤维的结晶度和取向度均高于纯PLLA纤维,当嵌段共聚物质量分数为2%时,共混纤维的结晶度及取向度最大,分别为27%和-0.39;嵌段共聚物的加入,对PLLA的热稳定性和力学性能的影响较小。     

聚乳酸固相接枝马来酸酐及与淀粉共混研究

通过固相接枝的方法,合成了聚乳酸与马来酸酐的接枝共聚物PLA-g-MAH,以改善其与淀粉共混物的相容性.研究了不同的接枝工艺条件对共聚物接枝率的影响,并考察了接枝聚乳酸与淀粉熔融共混物的力学性能和热性能.结果表明,在惰性气体环境中,聚乳酸可以和马来酸酐通过过氧化物引发而发生固相接枝反应.固定PLA100份,MAH 5份(质量比)不变,较好的工艺条件是引发剂用量为0.6份,120℃温度下反应1.4～1.6h.接枝聚乳酸与淀粉熔融共混,改善了聚乳酸和淀粉的相容性,提高了共混物的力学性能.     

PEG-HPMC固-固相变膜的制备及性能研究

通过原料筛选,配方优化,采用物理共混法,以聚乙二醇(PEG)和羟丙甲基纤维素(HPMC)为原料制备了PEG-HPMC固-固相变膜;对其进行了DSC、TG、XRD、透光率、SEM及力学拉伸的测试,讨论了PEG含量对膜热、力学等性能的影响规律。结果表明,PEG-HPMC固-固相变膜的热学性能主要取决于PEG的添加量,PEG添加量的增大相变焓及热稳定提高,但相变膜的屈服强度、断裂强度及弹性模量逐渐降低,断裂伸长率先增大后减小,当PEG添加量达到20%(质量分数)以上,相变膜从无色透明到乳白色不透明的突变。     

硼酸类复配物的固相制备及其热变色性能研究

采用固相法制备了龙胆紫-硼酸等系列可逆热致变色颜料.考察了其配比、无机填料的种类与用量、紫外线以及环境温度对其热变色性能的影响.结果表明:以龙胆紫:硼酸:氧化铝=1100:100～150制成的变色颜料变色敏锐,变色温度为65℃,复色时间为小于700s.     

Specific heats of solid hydrogen,solid deuterium,and solid mixtures of hydrogen and deuterium

Measurements have been made in the temperature range 0.5–5 K of the specific heats of pure solid H₂, pure solid D₂, and four solid mixtures of H₂ and D₂ with D₂ fractions between 15 and 95%, all of which systems had low concentrationc of molecules in the rotational stateJ=1. For the H₂,c=0.0023, and for the D₂,c=0.030. It was found that the observed specific heats could be described as the sum of three terms as follows. (1) A lattice specific heat. This was found to follow aT ³ function with _D =122 K for solid H₂ and _D=113.8 K for solid D₂. For the solid mixtures the lattice specifi heats have in first approximation values given by a weighted mean of the lattice specific heats of the pure components. (2) A Schottky term with a maximum at about 1.3 K for solid H₂ and 1.4 K for solid D₂, which can quantitatively be described in terms of electric quadrupole-quadrupole (EQQ) interactions in nearest-neighbor pairs and triples of molecules in the rotational stateJ=1. This term led to evaluation of , the EQQ interaction energy, giving /k=0.9 ± 0.1 K for solid H₂ and 0.93 ± 0.05 K for solid D₂. It was found, moreover, that in solid H₂ there was an appreciable enhancement with time of the number of clusters of molecules in the rotational stateJ=1 at the expense of the number of isolated singles of similar molecules, due to rotation diffusion. On the other hand no rotation diffusion was observed in solid D₂ or in the solid mixtures of H₂ and D₂, except possibly in those mixtures containing 85% H₂. (3) A second anomalous term occurring at temperatures below about 0.8 K and, by extrapolation, having its maximum below 0.5 K (the lowest temperature of our measurements). This anomaly was observed only in those samples containing D₂ and is, as yet, unexplained in detail. A further major conclusion from our results in the temperature range 0.5–5 K is that there was no evidence in the form of a sharp anomalous jump in the specific heat of any of the mixtures which could be interpreted as indicating the occurrence of isotopic phase separation. This absence of phase separation is noted, in spite of the fact that thermodynamically it is energetically favorable in the temperature range of observation.Work partially supported by a grant from the National Science Foundation and by contracts with the Office of Naval Research and DOD (Themis Program).     

Granular solid hydrodynamics

A complete continuum mechanical theory for granular media, including explicit expressions for the energy current and the entropy production, is derived and explained. Its underlying notion is: granular media are elastic when at rest, but turn transiently elastic when the grains are agitated—such as by tapping or shearing. The theory includes the true temperature as a variable, and employs in addition a granular temperature to quantify the extent of agitation. A free energy expression is provided that contains the full jamming phase diagram, in the space spanned by pressure, shear stress, density and granular temperature. We refer to the theory as GSH, for granular solid hydrodynamics. In the static limit, it reduces to granular elasticity, shown previously to yield realistic static stress distributions. For steady-state deformations, it is equivalent to hypoplasticity, a state-of-the-art engineering model.     

Au–Sapphire (0001) solid–solid interfacial energy

This work presents an experimental methodology for the measurement of interfacial energy (γ_SP) and work of adhesion (W _ad) of a metal–ceramic interface. A thin Au film was dewetted on the basal surface of sapphire substrates to form submicron-sized particles, which were analyzed using the Winterbottom method to determine the equilibrated particle–substrate solid–solid interfacial energy. Electron microscopy showed that a large portion of the particles contained grain boundaries, while all of the single crystalline particles had three distinct morphologies and orientations with the substrate. Two orientation relationships were determined from transmission electron microscopy, for which the interfacial energy in air at 1000 °C was determined: Au (111)–sapphire (0001): γ_SP = 2.15 ± 0.04 J/m², W _ad = 0.49 ± 0.04 J/m²; Au (100)–sapphire (0001): 2.18 ± 0.06 J/m², W _ad = 0.55 ± 0.07 J/m².     

Windowless solid hydrogen target

A windowless solid hydrogen target has been successfully developed for RI-beam-induced nuclear reactions in the RIKEN RI Beam Facility. Hydrogen crystals of high quality were grown reproducibly in a cell bored in a 10 mm thick pure copper plate which was in direct contact with a liquid helium reservoir. Normal hydrogen gas was crystallized directly on the cell wall between 4.7 and 7.3 K. The diameter of the crystal was 25 mm and the thickness was chosen to be either 5 or 10 mm. After crystallization, sidewalls of the cell were separated from both the crystal and cell plate, and removed to a remote position inside a cryostat. Thus, the crystal was self-supported in the cell without any extra material in its neighborhood. No damage was observed in the separating process. The observed hydrogen pressure indicated the crystal temperature of 4.3 K, when the liquid helium reservoir was at 4.2 K, in agreement with the temperature estimated from the heat balance in the crystal. It shows that we can put the crystal temperature close to the reservoir temperature, though we could not confirm the crystal temperature when the reservoir temperature was reduced to 3 K. Hydrogen sublimation rate was calculated from the vapor pressure and pumping condition. The sublimation loss is negligibly small if the crystal is held at 3 K.     

Resistivity of solid mercury

The resistivity ratio of polycrystalline pure mercury is obtained over the temperature range 1.65 to 234 K. At temperatures below 3 K this ratio is proportional to T⁵ and above 50 K to T. Measurements of magnetoresistance extrapolated to zero field are used below 4.2 K. At intermediate temperatures the data may be fit using the Gruneisen-Bloch equation with a characteristic temperature of 35 K. Corrections for resistivity at constant volume and size effects are discussed.     

New solid ionic conductors

A new class of solid Li⁺ ionic conductors has been found, related to the compound LiZr₂(PO₄)₃. Solid solutions of the type Li_1?xZr_2?xTa_x(PO₄)₃ and Li_1?xHf_2?xTa_x(PO₄)₃ have conductivities of about 10^?3ohm^?1 cm^?1 at 200°C, which are relatively independent of composition. These systems are compared with the recently discovered class of Na⁺ conductors Na_1+xZr₂P_3?xSi_xO₁₂. Other solid solutions are also discussed.     

Multi-component solid solution hardening

The model for multi-component solid solution hardening proposed in Part 1, is compared with experimental results. The observed ternary solid solution hardening in some f c c Cu-and Pb-base alloys and some b c c V-, Nb- and Ta-base alloys is shown to agree well with the predictions of the model.     

Diffraction-based solid immersion lens

A solid immersion lens based on diffraction (dSIL) is proposed as an alternative to the conventional design based on refraction. A design analogous to a Fresnel zone plate is derived in accordance with the Huygens-Fresnel principle. Fabrication of a binary dSIL is achieved by electron-beam lithography and reactive-ion etching on LaSF35, with index n = 2.014. Measurement of the point-spread function is performed with near-field optical microscopy. The results are in accord with the expected resolution enhancement of a factor n with respect to the diffraction limit.