可溶性聚酰亚胺规整多孔膜的形成与控制

选用4种聚合单体:4,4'-六氟亚异丙基一邻苯二甲酸酐(6FDA)、双酚A二酐(BPA-DA)、4,4'-二氨基二苯甲烷(MDA)、3,3'-二甲基-4,4'-二氨基二苯甲烷(DMMDA),采用低温溶液缩聚-化学亚胺化合成了3种可溶性的聚酰亚胺:6FDA-MDA,6FDA-DMMDA,BPADA-DMMDA,利用FI-IR、NMR等对其结构进行了分析表征,测试了它们的溶解性能与热性能.将这3种聚酰亚胺溶于氯仿溶液中,在高湿度环境下浇铸形成规整多孔膜结构;研究了其规整孔结构的拉伸与吹扫特定形变,最后还研究了所得的规整多孔膜的高温热稳定性,发现在350℃仍能保持规整结构的稳定.     

一类低溶胀率磺化聚芳醚砜质子交换膜材料的制备及性能

通过两步有机反应,设计合成了一种含3,5-二苯基苯侧基结构的活性二氟砜单体——3,3'-二(3,5-二苯基苯)-4,4'-二氟二苯砜。以此单体、4,4'-二氟二苯砜和4,4'-二羟基二苯甲酮为起始原料,经过芳香亲核取代缩聚和温和的后磺化反应,制备了一系列磺化聚芳砜质子交换膜(TS-PAS-xx)。分别利用红外光谱和核磁共振氢谱对所制聚合物的结构进行了表征分析。结果表明,所制质子交换膜表现出适中的吸水率和较低的溶胀率,在80℃时,膜的溶胀率均不超过15.7%。原子力显微镜测试表明这些质子交换膜形成了明显的"亲水-疏水"相分离结构,该结构有利于质子传导率的提高,80℃时TS-PAS-34膜的质子传导率达到了182 mS/cm,与Nafion112相当,优于其它已报道的一些具有相同离子交换容量(IEC)的聚芳砜质子交换膜的传导率。该膜还具有良好的热性能、力学性能和优异的耐化学氧化稳定性。     

RTM成型聚酰亚胺树脂的合成与性能研究

使用4-苯乙炔苯酐(4-PEPA),3,3',4,4'-二苯醚四酸二酐(ODPA),3,4-二氨基二苯醚(3,4-ODA),1,3-双(4-氨基苯氧基)苯(1,3,4-APB)和1,4-双(4'-氨基-2'-三氟甲基苯氧基)苯(6FAPB)分别合成了六种设计分子量为1250的聚酰亚胺低聚物RTM1-6,并对低聚物的熔体黏度及熔体黏度稳定性和热性能等进行了系统研究.实验结果表明,用含有醚键及氟原子的混合二胺合成的系列树脂,其熔体黏度较低,熔体稳定性较好,可用于RTM成型工艺.但树脂的玻璃化转变温度相对较低.     

联苯基聚芳亚胺的合成与热性能

以4,4-二溴联苯和芳香二胺为单体,以三(二亚苄基丙酮)二钯为催化剂,1.1'-联萘-2.2'-二苯膦(BINAP)为配体,由钯催化的胺基化反应缩聚合成了联苯基聚芳亚胺.其结构由红外、核磁氢谱和元素分析表征,表征结果与目标结构吻合良好.通过DSC和TG对其热性能进行分析,结果表明:联苯基聚芳亚胺具有良好的热稳定性(Tg＞250℃;TD＞510℃).     

无色透明耐高温聚酰亚胺薄膜的制备与性能研究

分别采用两种联苯型二酐单体,对称结构的3,3',4,4'-联苯四甲酸二酐(s-BPDA)以及不对称结构的2,3,3',4'-联苯四甲酸二酐(a-BPDA)与含氟芳香族二胺1,4-双(4'-氨基-2'-三氟甲基苯氧基)联苯(TFDAB)通过两步缩聚法制备了两种聚酰亚胺材料PI-1(s-BPDA/TFDAB)与PI-2(a-BPDA/TFDAB).研究结果表明,不对称结构可以显著增加PI薄膜在可见光区的透明性.25μm厚的PI-2薄膜在450nm处的透光率达到93%,而同样厚度的PI-1薄膜的透光率只有67%.此外,在PI分子结构中引入不对称结构不会牺牲材料的耐热稳定性、力学性能与介电性能.     

4,4'-对苯二甲酰二邻苯二甲酸酐和均苯四甲酸酐共聚酰亚胺的合成与性能

以4,4'-对苯二甲酰二邻苯二甲酸酐(TDPA)和均苯四甲酸酐(PMDA)为芳二酐单体,与4,4'-二氨基二苯醚(ODA)经溶液缩聚、热亚胺化制得PMDA/TDPA共聚酰亚胺薄膜,并用红外光谱、热重分析、差示扫描量热分析、力学性能测试等对薄膜的结构和性能进行表征。结果表明,在聚酰亚胺分子主链引入双酮基结构单元后,共聚酰亚胺树脂玻璃化转变温度(Tg)随着TDPA比例的增加逐渐下(Tg为322~285℃),溶剂流延成膜的加工性能得到显著改善,薄膜仍具有优良的热氧化稳定性和力学性能,5%热分解温度(Td5%)为517~550℃,拉伸强度为111~148 MPa。     

聚酰亚胺/二氧化硅杂化材料取向稳定性的研究

以5,5'-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)和4,4'-(六氟异丙基)-苯二酸酐(6FDA)或均苯四甲酸酐(PMDA)为单体,合成了含氟聚酰亚胺.采用溶胶-凝胶法得到了不同无机组分含量的热稳定性高的杂化材料,测定了它们的电光系数,其电光系数γ33在测试持续500min后保持其初始值的95%以上,说明材料可用于电光器件化.通过测定膜的极化前后的紫外-可见光谱,得到了取向发色团的序参数Ф(0.27～0.38),经60h序参数几乎不变.通过一维刚性气体模型研究了材料的宏观二阶非线性光学系数χ(2),结果表明材料的极化效率较高,设计合理,有较好的取向稳定性.     

含螺环结构的二胺及其聚酰亚胺的合成与性能

首先,以双酚A和甲磺酸反应合成出3,3,3',3'-四甲基-6,6'-二羟基-1,1'-螺旋双茚满,然后与2-氯-5-硝基三氟甲苯反应得到3,3,3',3'-四甲基-6,6'-双[4-硝基-2-三氟甲基苯氧基]-1,1'-螺旋双茚满,最后在Pd/C-水合肼还原作用下得到3,3,3',3'-四甲基-6,6'-双[4-氨基-2-三氟甲基苯氧基]-1,1'-螺旋双茚满。采用上述二胺单体分别与1,2,3,4-环丁烷四酸二酐、均苯四甲酸二酐、联苯二酐、3,3',4,4'-二苯醚四酸二酐、3,3',4,4'-二苯酮四酸二酐和六氟二酐通过两步法制备出6种含螺环结构的聚酰亚胺(PI)。采用核磁、红外光谱、X射线衍射、紫外-可见光谱、热重分析、差示扫描量热分析和溶解性测试等手段表征了所得化合物和PI的结构与性能。研究结果表明,这些含螺环的PI主要表现为非晶结构和较大的分子链间距离,且具有良好的溶解性、光学性能和热性能。     

1,4环己二甲醇改性聚对苯二甲酸乙二酯

聚对苯二甲酸乙二酯 (PET)是由对苯二甲酸 (TPA) (或对苯二甲酸二甲酯 (DMT) )与乙二醇 (EG)缩聚而成的。如果在PET的生产中用 1,4环己二甲醇 (CHDM )部分取代EG ,经共缩聚所得聚酯即为CHDM改性PET的ET/CT共聚酯。本文概述了ET/CT共聚酯的研发现状、制备、性能和应用     

一种非氟掺杂型质子交换膜材料的制备及表征

将自制的二氮杂萘酮类双酚(DHPZ)、磺化4,4'-二氯二苯砜(SDCS-Na),与商用双酚A(BPA)及4,4'-二氟二苯酮(DFK)进行溶液直接共缩聚反应,合成一系列磺化度可任意调控的新型磺化聚芳醚砜酮(SPBESKs)共聚物.将此聚合物与聚醚酮(PPEK)以7∶3(质量比)溶解在N-甲基-2-吡咯烷酮(NMP)中配成10%(质量分数)的成膜液,60℃下刮制成膜.用FTIR、1H-NMR和特性粘度(η)等手段对聚合物进行了表征,并对膜的性能进行了研究.研究结果表明掺杂PPEK后成膜性提高,膜的含水率、溶胀率、离子交换能力(IEC)、水解稳定性、抗氧化性等随磺化度的变化呈一定的规律性,聚合物磺化度0.70和0.80的膜IEC值分别为1.04和1.29mmol/g.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。     

Synthesis and luminescent properties of alkali-metal and ammonium fluorosulfatozirconates and fluorosulfatohafnates

We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390–440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K₂SO₄, and relative amounts of fluorine and SO₄ groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb₃Zr₂F₉SO₄ · 2H₂O, Cs₂ZrF₂(SO₄)₂ · 2H₂O, Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O, and Cs₂ZrF₄SO₄ offer the most efficient RL.     

The shape and stability of wall-bound and wall-edge-bound drops and bubbles

The behavior of wall-bound drops and bubbles is fundamental to many natural and industrial processes. Key characteristics of such capillary systems include interface shape and stability for a variety of gravity levels and orientations. Significant solutions are in hand for axisymmetric pendent drops for a variety of uniform boundary conditions along the contact line with gravity acting normal to a planar wall. The special case of a wall-bound drop or bubble that is also pinned at an edge (i.e. a ‘wall-edge-bound’ drop) is considered here where numerical solutions are obtained for interface shape and stability as functions of drop volume, contact angle, fluid properties, and uniform gravity vector. For a semi-infinite zero-thickness planar wall (plate), a critical contact angle is identified below which wall-edge-bound drops are always stable. The critical contact angle is computed as a function of the gravity vector. The numerical procedure, which makes no account for contact angle hysteresis, predicts that such wall-edge-bound drops are unconditionally unstable for any gravity field with a component that is tangent to the wall while inwardly normal to the edge. Select experiments are conducted that support the conclusions drawn from the numerical results.     

凝固科学技术与材料

从凝固科学与实践发展的角度介绍了当前凝固材料体系的基本框架和凝固科学主要发展阶段的基本理论。作为材料科学与工程的基本组成，凝固科学技术正在现代科学理论的基础上针对传统材料的改性提高和新材料的发展需求，以控形、控构、控性为目标开展优质铸件的定向、晶体生长、快凝、深过冷及各种新型和超常领域凝固过程的研究，并介绍了其中某些方面和展望了可能的发展趋势。     

Heat and Mass Transfer and Modeling and Prediction of Environmental Catastrophes

Basic definitions and concepts of the physicomathematical theory of natural catastrophes are given. Possibilities of mathematical modeling of natural and technogenic catastrophes are discussed in the context of the theory of heat and mass transfer and the mechanics of reacting media. The importance of taking into account conjugate heat and mass exchange in modeling catastrophes is emphasized. A formula for evaluating the probability of a collisional catastrophe is given.     

Multi-ferroic and magnetoelectric materials and interfaces

The existence of multiple ferroic orders in the same material and the coupling between them have been known for decades. However, these phenomena have mostly remained the theoretical domain owing to the fact that in single-phase materials such couplings are rare and weak. This situation has changed dramatically recently for at least two reasons: first, advances in materials fabrication have made it possible to manufacture these materials in structures of lower dimensionality, such as thin films or wires, or in compound structures such as laminates and epitaxial-layered heterostructures. In these designed materials, new degrees of freedom are accessible in which the coupling between ferroic orders can be greatly enhanced. Second, the miniaturization trend in conventional electronics is approaching the limits beyond which the reduction of the electronic element is becoming more and more difficult. One way to continue the current trends in computer power and storage increase, without further size reduction, is to use multi-functional materials that would enable new device capabilities. Here, we review the field of multi-ferroic (MF) and magnetoelectric (ME) materials, putting the emphasis on electronic effects at ME interfaces and MF tunnel junctions.