A new class of high T-g and organosoluble polynaphthalimides

A new class of soluble six-membered ring polynaphthalimides (PNIs) was synthesized from asymmetrical fluorinated naphthalenesubstituted monomers. All the resulting PNIs were easily soluble in many organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO). and chloroform. They also showed good thermal stability with glass transition temperature of 340-386 degrees C, 10% weight loss temperature in excess of 529 degrees C. Polyimide 3c could be solution-cast into tough and flexible film. The film had a tensile strength, elongation at break, and Young's modulus of about 117.6 Wa, 23.6%, and 1.77 GPa, respectively. The gas permeation property of the film of 3c was investigated with oxygen permeability coefficient (PO2 = 3.99) and permeability selectivity coefficient of oxygen to nitrogen (P-O2/P-N2 = 5.27). Therefore, these materials are expected to be a good alternative to PIs based on five-membered rings with applications in gas separation membranes.

Synthesis and properties of novel fluorinated poly(phenylene-co-imide)s

A new class of high-performance materials, fluorinated poly(phenylene-co-imide)s, were prepared by Ni(0)-catalytic coupling of 2,5-dichlorobenzophenone with fluorinated dichlorophthalimide. The synthesized copolymers have high molecular weights ((M) over bar (W)= 5.74 x 10(4)-17.3 x 10(4) g center dot mol(-1)), and a combination of desirable properties such as high solubility in common organic solvent, film-forming ability, and excellent mechanical properties. The glass transition temperature (T(g)s) of the copolymers was readily tuned to be between 219 and 354 degrees C via systematic variation of the ratio of the two comonomers. The tough polymer films, obtained by casting from solution, had tensile strength, elongation at break, and tensile modulus values in the range of 66.7-266 MPa, 2.7-13.5%, and 3.13-4.09 GPa, respectively. The oxygen permeability coefficients (P-O2) and permeability selectivity of oxygen to nitrogen (P-O2/P-N2) of these copolymer membranes were in the range of 0.78-3.01 barrer [1 barrer = 10(-10) cm(3) (STP) cm/(cm(2) center dot s center dot cmHg)] and 5.09-6.2 5, respectively. Consequently, these materials have shown promise as engineering plastics and gas-separation membrane materials.

聚丙撑碳酸酯的辐射效应

研究了室温条件下聚丙撑碳酸酯(PPC)在钴-60和电子加速器辐照过程中的响应行为。结果表明,聚丙撑碳酸酯是一种辐射裂解型聚合物,其分子量随着辐射剂量的增加而减小。1mm厚PPC片材在室温和N2气保护条件下,其裂解G值为Gs,γ-ray=10.81;Gs,EB=4.9。不同的裂解G值表明,O2气在聚丙撑碳酸酯的辐射裂解过程中有重要影响。红外光谱研究表明,辐射后聚丙撑碳酸酯在3474cm-1处的峰宽峰高增加,表明其裂解后端—OH基增加。由于裂解作用,辐射后聚丙撑碳酸酯的抗张强度和断裂伸长率均下降。在通常的辐射消毒剂量范围内(25~50kGy),PPC的保留抗张强度大于23MPa,断裂伸长率大于4%,裂解后试样的力学性能依然能够满足实际应用需要,因此PPC可以经受辐射消毒。

荷电型聚芳醚酮气体分离膜的研究——磺化度与中和离子对H_2/N_2气体透过行为的影响

以聚芳醚酮为主链,经磺化引入荷电基团(-SO3H)制得了具有不同磺化度和不同中和盐型的均质膜.测试了它们不同温度下的H2/N2透过行为,讨论了磺化度和中和离子对其透过行为的影响,并证明了荷电化可以提高均质膜对H2/N2的分离系数.

Synthesis, structural characterization and electrical property of new oxide ion conductors: La3MMo2O12 (M = In, Ga and Al)

New series of oxides, La3MMo2O12 (M = In, Ga and Al), have been prepared by the solid-state reaction. The composition and elemental distribution were analyzed by the energy-dispersive X-ray (EDX) analysis. As determined by the X-ray diffraction (XRD), these compounds have similar crystal structures that can be indexed on a monoclinic cell at room temperature. AC impedance spectra and the DC electrical conductivity measurements in various atmospheres indicate that they are oxide ion conductors with ionic conductivities between 10(-2) and 10(-3) S/cm at 800 degrees C. The conductivity decreases in the order of La3GaMo2O12 > La3AlMo2O12 > La3InMo2O12, implying that the effect of cell volume and polarization associated with In3+, Ga3+ and Al3+ play an important role in the anion transport of these materials. The reversible phase transition was observed in all these compounds as confirmed by the differential thermal analysis (DTA) and dilatometric measurements.

A new oxide ion conductor: La3GaMo2O12

A new oxide ion conductor, La3GaMo2O12, with a bulk conductivity of 2.7 X 10(-2) S.cm(-1) at 800 degrees C in air atmosphere was prepared by the traditional solid-state reaction. The room temperature X-ray diffraction data could be indexed on a monoclinic cell with lattice parameters of a=0.5602(2) nm, b=0.3224(1) nm, c= 1.5741(1) nm, beta= 102.555(0)degrees, V=0.2775(2) nm(3) and space group Pc(7). Ac impedance measurements in various atmospheres further support that it is an oxide ion conductor. This material was stable in various atmospheres with oxygen partial pressure P(O-2) ranging from 1.0 X 10(5) to 1.0 X 10(-7) Pa at 800 degrees C. A reversible polymorphic phase transition occurred at elevated temperatures as confirmed by the differential thermal analysis and dilatometric measurement.

Pt羰基簇合物途径制备的Pt/C催化剂对甲醇的电催化氧化

通过Pt羰基簇合物在N2气氛下于150℃热分解制得了无定形的碳载纳米Pt催化剂.发现甲醇在这种催化剂上氧化的起始电位和峰电位均比在传统的液相还原法制得的Pt/C催化剂上发生了负移,峰电流也有明显的增加,且稳定性好.表明通过Pt羰基簇合物热分解制备Pt/C催化剂是一种较好的制备甲醇氧化电催化剂的方法.

Gas transport properties of novel cardo poly(aryl ether ketone)s with pendant alkyl groups

Gas transport of hydrogen, oxygen, nitrogen, carbon dioxide, and methane in four cardo poly(aryl ether ketone)s containing different alkyl substituents on the phenyl ring has been examined from 30 to 100 degrees C. The permeability, diffusivity, solubility, and their temperature dependency were studied by correlations with gas shape, size, and critical temperature as well as polymeric structural factors including glass transition, secondary transition, cohesive energy density, and free volume. The bulky, stiff cardo and alkyl groups in tetramethyl-substituted TMPEK-C resulted in increased H-2 permeability (by 55%) and H-2/N-2 permselectivity (by 106%) relative to bisphenol A polysulfone (PSF). Moreover, the weak dependence of gas transport on temperature in TMPEK-C made it maintain high permselectivities (alpha(H2/N2) in 68.3 and alpha(O2/N2) in 5.71) up to 100 degrees C, exhibiting potential for high-temperature gas separation applications.

Synthesis and thermal polymerization of a novel stilbene-maleimide AB-monomer

A novel AB-monomer, 3-maleimidostilbene (ST-MAI), was synthesized. DSC investigation indicated that the ST-MAI monomer melted at 127 degrees C and thermally polymerized in the temperature range of 180 similar to 300 degrees C. LR investigation on the thermal polymerization processes proved that the thermal polymerization included not only copolymerizaiton between stilbene and maleimide, but also homopolymerization of maleimide. The largest reaction conversion of maleimide and stilbene unit in a ST-MAI monomer was about 82% and 50% respectively. The glass transition temperature of cured ST-MAI resin was 234 degrees C, determined by DSC. The decomposition temperatures for 10% weight loss was above 430 degrees C in both air and nitrogen atmospheres.

水滑石衍生复合氧化物的CO催化还原NO的性能

研究了以含Co水滑石类化合物为前体、经焙烧制得的复合氧化物催化剂对CO催化还原NO的催化作用，结果表明，这样制得的催化剂的活性远远高于由传统方法制备的具有尖晶石结构的催化剂，反应分步进行，NO先与CO反应生成N2O和CO2，随着反应温度的升高，最终得到的是N2和CO2，在所考察的催化剂中，反应活性随催化剂中Co含量的增加而升高，随焙烧温度的升高而降低，催化剂中晶格缺陷对活性有重要影响。

Effects of molecular structure on the permeability and permselectivity of aromatic polyimides

Permeability coefficients of H-2, O-2, and N2 were measured under 10 atm at the temperature from ambient temperature up to 150 degrees C in a series of structurally different aromatic homo- and copolyimides, which were prepared from 4,4'-oxydianiline (ODA) or 4,4'-methylene dianiline (MDA) with various aromatic dianhydrides. The study shows that the molecular structure of the polyimides strongly influences gas permeability and permselectivity. As a result, the permeability coefficients of the polyimide membranes for each gas vary by over two orders of magnitude. In general, among the polyimide membranes studied, the increase in permeability of polymers is accompanied by the decrease in permselectivity, and the MDA-based polyimide membranes have higher permeability than ODA-based ones. Among the polyimides prepared from bridged dianhydrides, the permeability coefficients to H-2, O-2, and N-2 are progressively increased in the order BPDA < BTDA < ODPA similar to TDPA < DSDA ( SiDA < 6FDA, while H-2/N-2 and O-2/N-2 permselectivity coefficients are progressively decreased in the same order. The copolyimide membranes, which were prepared from 3,3',4,4' biphenyltetracarboxylic dianhydride (BPDA), bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride (SiDA), and ODA, have favorable gas separation properties and are useful for H-2/N-2 separation applications. (C) 1996 John Wiley & Sons, Inc.

THE VALENCY AND SPECTRA OF SAMARIUM IONS IN MF(2)-MGF2 (M=CA, SR, BA)

The phosphors MMgF(4)(M = Ca, Sr, Ba) doped with samarium ions are synthesized in different atmospheres using solid phase reaction at high temperature. Samarium has been first stabilized in the divalent state in SrMgF4 and BaMgF4 matrices. Effects of matrices on the valent state of samarium ions are briefly discussed.

VALENCY AND ITS CHANGE PROCESS OF SAMARIUM ION IN SAMARIUM FLUORIDE SYSTEM

Nonstoichiometric series SmF(x) (2.0 less-than-or-equal-to x less-than-or-equal-to 3.0) have been synthesized by reduction of samarium trifluoride with hydrogen for several times, and the stoichiometric samarium difluoride has been obtained. The structure of nonstoichiometric samarium fluoride series and the valency of samarium ion are briefly discussed. The valent change process of samarium ion at high temperatures in different atmospheres is investigated.

GAS PERMEABILITIES OF POLY(TRIMETHYLSILYLPROPYNE) MEMBRANES SURFACE MODIFIED WITH CF4 PLASMA

Surface fluorination of poly (trimethylsilylpropyne) (PTMSP) membranes by CF4 plasma was studied. The surface fluorination of the membranes was carried out in an atmosphere of CF4 in a capacitively coupled discharge apparatus with external electrodes. Dramatic increase in selectivity (P(O2)/P(N2)) was observed. The effect of fluorination conditions such as duration of treatment and discharge power on the permeabilities of the membranes was studied. X-ray photoelectron spectrometric data of modified PTMSP membranes showed a drastic alternation in the surface layer. The P(O2) and P(O2)/P(N2) of the membranes were observed to be dependent on the F/C atomic ratio. At F/C > 1, the P(O2/P(N2) value of the membranes could be more than four.

电子能谱法研究改性的聚丙烯纤维性能与结构关系

本文讨论了聚丙烯纤维（PPF）在Ar、N2、O2和空气等离子体作用时，改变时间和功率对PPF表面进行等离子体处理，发现处理后纤维的吸湿性变化很大，回潮率是未处理样品的120-400%，染色性能从5级提高到1级标准。这一变化的光电子能谱法研究结果表时：PPF表面的结构发生较大变化。表面大量引入含O、N极性基团。经谱图拟合可知，这些基团是亲水性的极性结构，应归属于C-OH、C=O、COOH、C-NH2和CONH2基团。