Degradation of poly(p-phenylene benzobisthiazole) (PBT) rigid rod,poly(ether ether ketone ether ketone) (PEEKEK) semi-flexible coil,and a grafted “hairy rod” polymer containing PBT and PEEKEK

Thermal degradation pathways of the rigid-rod polymer, poly (p-phenylene benzobisthiazole, PBT) have been elucidated by thermal volatilization analysis and related techniques. Processes are characterized by the expulsion of hydrogen sulphide, acetylene, and some carbon disulphide. Evidence is presented for the production and subsequent polymerization of aromatic nitriles and for the existence of thermal rearrangements to produce quinoline derivatives. A similar analysis of the semi-flexible coil polymer, poly (ether ether ketone ether ketone, PEEKEK) revealed the importance of directed chain-scission processes to form oligomers, carbon monoxide expulsion with radical recombination to produce biphenyl linkages, and aromatic fusions to produce fluorenone-type derivatives. Examination of a hairy rod comb-type graft copolymer of PBT and PEEKEK revealed some instability introduced by the grafting process and determined that the graft site thermally isomerized through oxygen migration to yield xanthone-based heterocyclic intermediates of degradation.     

Poly(phenylene sulphide) and poly(ether ether ketone) composites reinforced with single-walled carbon nanotube buckypaper: I – Structure,thermal stability and crystallization behaviour

Single-walled carbon nanotube (SWCNT) buckypaper (BP) reinforced-poly(phenylene sulphide) (PPS) and poly(ether ether ketone) (PEEK) composite laminates were manufactured through hot-press processing. Scanning and transmission electron microscopies were used for morphological characterization and qualitative evaluation of the impregnation degree of the BP. The thermal stability, resin and void content of the composites were evaluated through thermogravimetric analysis; a strong increase in the degradation temperatures of the polymers was found. Raman spectra revealed the existence of strong filler–matrix interactions. The glass transition temperature, crystallization and melting behaviour of the composites were investigated through differential scanning calorimetry and their crystalline structure was analyzed by wide angle X-ray diffraction. This investigation confirms that SWCNT-BPs can be used to fabricate high-loading CNT/thermoplastic composites with improved thermal properties.     

Ionic polymer–metal composite actuators obtained from sulfonated poly(ether ether sulfone) ion-exchange membranes

The cost-effective and high-performance ionic polymer–metal composites (IPMC) were designed and prepared from ion-exchange membranes based on sulfonated poly(ether ether sulfone) (SPEES) with different degrees of sulfonation (DS). The precursor of SPEES, namely PEES, is commercially available and industrial grade. Moreover, the PEES can be transformed easily into ion-conductive SPEES through a simple sulfonation reaction. The ion exchange capacity (IEC) and water uptake (WU) of SPEES membranes increase with increasing their DS, and the proton conductivities of these hydrated SPEES membranes are subsequently enhanced. Compared with the commercial Nafion ion-exchange membrane, the SPEES membranes have higher IEC and WU. The IPMC actuators made of the SPEES membranes show the large bending strain and fast response under electric stimulation. The SPEES membrane with the highest DS (SPEES4) shows the best performance of IPMC actuators. The electromechanical behaviors of these IPMC actuators indicate that the SPEES is a candidate to substitute Nafion.     

测试(measurement and test)

具有试验性质的测量。一般认为，计量器具示值的检定或校准，有规范化的技术文件可依，可以通称为测量或计量，而除此以外的测量，尤其是对不属于计量器具的设备、零部件、元器件的参数或特性值的确定，其方法具有试验性质，一般就称为测试。测试(measurement and test)     

Poly(acrylonitrile-co-itaconic acid)–poly(3,4-ethylenedioxythiophene) and poly(3-methoxythiophene) nanoparticles and nanofibres

This work aimed to produce poly(acrylonitrile-co-itaconic acid) (P(AN-co-IA)) nanocomposites with poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-methoxythiophene) (PMOT). An anionic surfactant sodium dodecyl benzene sulphonate was used in emulsion polymerization for nanocomposite production. Incorporations of PEDOT and PMOT on the nanoparticles were characterized by scanning electron microscopy (SEM), atomic force microscopy, Fourier transform infrared-attenuated total reflectance spectroscopy and ultra-violet spectroscopy. These nanoparticles were blended with PAN and the blends were electrospun to produce P(AN-co-IA)–polythiophene-derivative-based nanofibres, and the obtained nanofibres were characterized by SEM and energy dispersive spectroscopy. In addition, electrochemical impedance studies conducted on nanofibres showed that PEDOT and PMOT in matrix polymer P(AN-co-IA) exhibited capacitive behaviour comparable to that of ITO–PET. Their capacitive behaviour changed with the amount of electroactive polymer.     

Eu(3+) doped gadolinium oxysulfide (Gd(2)O(2)S) nanostructures-synthesis and optical and electronic properties

One-dimensional Eu(3+) doped gadolinium oxysulfide (Gd(2)O(2)S:Eu(3+)) nanotubes/nanorods have been synthesized via precursors of Gd(OH)(3) nanostructures using a hydrothermal technique. The blue-shifts in the optical spectra for the Gd(2)O(2)S:Eu(3+) system corresponding to the fundamental absorption and Eu(3+)-X(2-) ligand (X = O/S) charge transfer bands (CTBs) are significant (～0.22-0.36?eV) with respect to the bulk counterpart. The nanotubes are good candidates for investigating the size-induced electrical and optical properties of functional oxysulfides. In order to identify the origin and nature of the electronic transitions observed in the visible region, optical and photo-induced impedance measurements have been extended to the nanotubes in this report.     

Work Functions of Pd_(83.5)Si_(16.5)and Cu_(70)Ti_(30)Glassy Alloys

The work functions before and aftercrystallization of two glassy alloys,Pd_(83.5)Si_(16.5) andCu_(70)Ti_(30) have been measured by means of the con-tact potential difference method in the secondaryelectron field at room temperature under 10~(-5) Pavacuum.The results show that the work functionsof both glassy alloys are higher than those of thecorresponding crystalline alloys.     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

Electrical and humidity sensing properties of lead(II) tungstate–tungsten(VI) oxide and zinc(II) tungstate–tungsten(VI) oxide composites

Lead(II) tungstate and zinc(II) tungstate were prepared by a solution route and sintered at 973 K in the form of cylindrical discs. Experimental results on PbWO₄ (PW) and WO₃ (WO) composites for humidity sensing are described. Sintered polycrystalline discs of PbWO₄ (PWWO-10), WO₃ (PWWO-01), ZnWO₄ (ZWWO-10) and composites of PW or ZW and WO in the mole ratios 8:2, 6:4, 4:6, 2:8 designated as PWWO and ZWWO-82, 64, 46 and 28, respectively and doped with 2 mol% of Li⁺ were studied. The composites were subjected to dc conductance measurements over the temperature range 373–673 K in air atmosphere from which activation energies were determined. The activation energy values for dc conductance were found to be in the range of 1.09–1.30 eV. The composites were identified by powder XRD data. The scanning electron microscopy (SEM) studies were carried out to study the surface and pores structure of the sensor materials. The composites were subjected to dc resistance measurements as a function of relative humidity in the range of 5–98% RH, achieved by different water vapor buffers thermostated at room temperature. The sensitivity factor (S_f=R_5%/R_98%) measured at 298 K revealed that PWWO-28 and ZWWO-46 composites have the highest humidity sensitivity factor of 17 615±3000 and 2666±550, respectively. The response and recovery time for these humidity sensing composites were good.     

δ-FeO (OH) and its solutions

Decomposition products of -FeO(OH)-type Fe_1–x M _x O_1–x (OH)_1+x phases (M=Mg, Zn, Ca, Cd) have been studied by X-ray diffraction, electron diffraction and high-resolution transmission electron microscopy. It has been shown that the M=Mg and Cd -phases decompose to -Fe₂O₃-based solid solutions which in turn undergo exsolution to form some MgO and CdO at a higher temperature. In the case of Fe_1–x Zn _x O_1–x (OH)_1+x , the decomposition proceeds over -Fe₂O₃ ss to an unstable spinel solid solution. All decomposition products are topotactically related to their precursors in the decomposition chain. In the electron microscope some -type phases undergo in situ decomposition under intense beam bombardment with somewhat different results than obtained for thermal decomposition products under ambient conditions. The plate-like morphology and crystal size is retained in the decomposition products; however, the products have a more pitted appearance after decomposition.     

Synthesis and properties of LiZr2(AsO4)3 and LiZr2(AsO4) x (PO4)3 − x

The LiZr₂(AsO₄)₃ arsenate and LiZr₂(AsO₄) _x (PO₄)_{3 ? x} solid solutions have been prepared through precipitation followed by heat treatment, and characterized by X-ray diffraction, X-ray structure analysis, IR spectroscopy, and impedance spectroscopy. We have established conditions for the crystallization of the arsenate and a continuous series of arsenate phosphate solid solutions (0 ≤ x ≤ 3), which have been obtained as two polymorphs: monoclinic and hexagonal. Using the Rietveld method, we have refined the crystal structures of the polymorphs of LiZr₂(AsO₄)₃ (sp. gr. P2₁/n, a = 9.1064(2), b = 9.1906(2), c = 12.7269(3) Å, β = 90.844(2)°, V =1065.03(5) ų, Z = 4; sp. gr. R $\bar 3$ c, a = 9.1600(4), c = 22.9059(13) Å, V = 1664.44(14) Å, Z = 6) and LiZr₂(AsO₄)_1.5(PO₄)_1.5. Their structural frameworks are built up of AsO₄ tetrahedra—or (As,P)O₄ tetrahedra occupied by arsenic and phosphorus atoms at random—and ZrO₆ octahedra, with the lithium atoms in between. The ionic conductivity of the materials has been measured. The cation conductivity of monoclinic LiZr₂(AsO₄) _x (PO₄)_{3 ? x} with 0 ≤ x ≤ 1 has been shown to exceed the conductivity of lithium zirconium phosphate.     

γ-Cu2(OH)3Cl as precursor in the preparation of copper (I) and (II) oxides and copper powder

When-Cu₂(OH)₃Cl is decomposed in air or nitrogen flow, different amounts of cuprous oxide are obtained as final product depending on both the heating rate and the ambient atmospheres. However, the temperature of formation of cuprous oxide only appears to depend on the partial pressure of oxygen. When thermal decomposition is carried out under dynamic vacuum in the X-ray high-temperature diffraction chamber, using a tantalum strip as the heating element, copper is obtained as final product at a comparatively low temperature.     

Structural and Magnetic Properties of Sm_3(Fe,Ti)_(29) and Sm_3(Fe,Ti)_(29)X_y (X=H, N) Compounds

1. IntroductionRecelltly new intermetallic compounds NdZ(Fe,Ti)lo and RZ(Feo.91Vo.og)19 (R=Y, Nd, Sin, Gd) werediscovered by Collocott et al.II] and Shcherbakovaat al.IZ], respectively. The crystal structure of thesenew phases has been identified to be Nd3(Fe, Ti)29type structure using X-ray diffraction by Li et al.I3].Among them, the Sin3(Fe,Ti)29N. compound exhibitsstrong uniaxial anisotropy' and its saturation magnetization is very close to that of S.,Fe,,N;'] compound.The hydr…     

Preparation and properties of polyrotaxane from α-cyclodextrin and poly(ethylene glycol) with poly(vinyl alcohol)

α–Cyclodextrin (α-CD) was found to form inclusion complexes with poly(ethylene glycol) (PEG) having a crystalline state in high yields, which have been investigated extensively in the past. Formation of an inclusion complex depends strongly on structure, molecular weight and geometry of the polymer. Development of a dicomponent inclusion complex (DIC) of PEG and α-CD in the presence of poly(vinyl alcohol) (PVA) and initiation of hexagonal crystals upon sonication have exhibited various microstructures. Formation of the new inclusion complex in PVA heavily depends on the concentration of PVA, temperature and sonication time. The complexes produced are characterized by FTIR, HNMR spectra and powder X-ray. ¹HNMR of the complexes demonstrate that their stoichiometric ratio is 2:1 (two ethylene glycol units and one α-CD). X-ray patterns of PEG–α-CD complex indicate that the α-CD forms channels whereas PEG/α-CD/PVA creates cage-type structures.     

Glass-Forming Ability for Nd_(70-x)Fe_(20)Al_(10)Y_x and Nd_(60-x)Fe_(30)Al_(10)Y_x Alloys

The glass-forming ability (GFA) of Nd70-xFe2oAl10Yx and Nd60-xFe30Al10Yx (0< x <15) alloys produced by Cu mold casting was investigated. Except Y=5 at. pct, bulk amorphous Nd70-xFe20Al10Yx alloys up to 2 mm in diameter were obtained. The GFA for Nd60-xFe30Al10Yx alloys, however, was found to decrease with increase of Y due to the increasing compositional deviation from the original eutectic point of Nd60Fe30Al10 alloy. The Nd60Fe20Al10Y10 and Nd60Fe30Al10 alloy exhibit the largest GFA and can be cast into bulk amorphous cylindrical specimens of 3 mm in diameter. The melting temperature or/and the reduced crystallization temperature is closely related to the GFA of Y-containing alloys. The bulk amorphous cylinder for the Nd55Fe20Al10Y15 alloy shows a distinct glass transition temperature and a wide supercooled liquid region before crystallization. The crystallization temperature, Tg, and the supercooled liquid region, TX, are 776 K and 58 K, respectively. The GFA and thermal stability of the Nd-Fe-AI-Y a