Reactive blending of modified polypropylene and polyamide 12: Effects of compatibilizer content on crystallization and blend morphology

The crystallization behavior and morphology of nonreactive and reactive melt-mixed blends of polypropylene (PP) and polyamide (PA12; as the dispersed phase) were investigated. It Was found that the crystallization behavior and the size of the PA12 particles were dependent on the content of the compatibilizer (maleic anhydride-modified polypropylene) because an in situ reaction occurred between the maleic anhydride groups of the compatibilizer and the amide end groups of PA12. When the amount of compatibilizer was more than 4%, the PA12 did not crystallize at temperatures typical for bulk crystallization. These finely dispersed PA12 particles crystallized co-incidently with the 1313 phase. The changes in domain size with compatibilizer content were consistent with Wu's theory. These investigations showed that crystallization of the dispersed phase Could not be explained solely by the size of the dispersion. The interfacial tension between the polymeric components in the blends may yield information on the fractionation of crystallization.

Neodymium oxide-assisted melt free-radical grafting of maleic anhydride on isotactic-polypropylene by reactive extrusion

Rare earth oxide, neodymium oxide (Nd2O3), -assisted melt free-radical grafting of maleic anhydride (MAH) on isotactic-polypropylene (i-PP) was carried out by reactive extrusion. The experimental results reveal that the addition of Nd2O3 into reactive system leads to an enhancement of the grafting degree of MAH, along with an elevated degradation of i-PP matrix. When Nd2O3 content is 4.5 mmol %, the increment of the grafting degree of MAH (maximally) is up to about 30% compared with that of the related system without adding Nd2O3, while the severest degradation of i-PP matrix simultaneously occurs. On the basis of the reaction mechanism of PP-g-MAH proposed before, the sequence of beta-scission and grafting reaction is discussed in detail. It is found that, for the reactive system studied, most tertiary macroradicals first undergo beta-scission, and then, grafting reaction with MAH takes place at the new radical chain ends. The imported Nd2O3 has no effect on the aforementioned reaction mechanism, whereas it enhances the initiating efficiency of the initiator, dicumyl peroxide (DCP).

Synthesis, structure and reactive mechanism of intermetallic W3Mg

Assisted by mechanical alloying and high-pressure technique, a new W3Mg intermetallic was formed. W3Mg amorphous mixture was obtained by mechanically alloying the pure metal powder mixtures at designated composition for 20 h. A new compound was found after the Subsequent high pressure and high temperature treatment. W3Mg intermetallic was identified as a tetragonal structure and the lattice parameter was a = 0.7880 nm, c = 0.7070 nm. The synthesis mechanism is also discussed in this paper.

Synthesis, structure and reactive mechanism of intermetallic W4Mg

Assisted by a mechanical alloying and high-pressure technique, a new W4Mg intermetallic was formed. W4Mg amorphous mixture was obtained by mechanically alloying the pure metal powder mixtures at designated composition for 20 h. A new compound was found after the subsequent high-pressure and high-temperature treatment. W4Mg intermetallic was identified as a cubic structure and the lattice parameter was a=0.4150 nm. The synthesis mechanism is also discussed in this paper.

Novel highly selective anion chemosensors based on 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole

2-(2-Hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole 1 and 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole 2 were used as anion fluorescent and colorimetric chemosensors with high selectivity for H2PO4- and F- over Cl-, while 2 can even distinguish H2PO4- from F-. (C) 2002 Elsevier Science Ltd. All rights reserved.

A new type of highly efficient luminescent material - The system Al2O3-B2O3 containing Ce3+ and Tb3+ ions

The system Al2O3-B2O3 containing Ce3+ and Tb3+ ions was investigated for the first time. It was found that certain compositions give rise to a new highly efficient green luminescent material.

Novel, highly active binuclear 2,5-disubstituted Amino-p-benzoquinone-nickel(II) ethylene polymerization catalysts

Reaction of salts of the 2,5-disubstituted amino-p-benzoquinone bridging ligand (la-e) with trans-bis(triphenylphosphane)phenylnickel(II) chloride results in the binuclear complexes 2a-e, which show high activities for ethylene polymerization without any cocatalysts. High-molecular-weight, moderately branched polyethylene of broad molecular-weight distribution was obtained.

Reactive compatibilization of polyamide 6 with isocyanate functionalized ethylene-propylene copolymer

Reactive compatibilization of ethylene-propylene copolymer functionalized with allyl (3-isocyanato-4-tolyl) carbamate (TAI) isocyanate (EPM-g-TAI) and polyamide 6 (PA6) was investigated in this paper, FTIR analysis revealed the evidence of a chemical reaction between the end groups of PA6 and EPM-g-TAI. Thermal, rheological, morphological, and mechanical properties of the resultant system were examined, DSC analysis indicated that the crystallization of PA6 in Pa6/EPM-g-TAI blends was inhibited, due to the chemical reaction that occurs at the interface of PA6 and EPM-g-TAI. Rheological measurement showed that complex viscosity and storage modulus of PA6/EPM-g-TAI were both dramatically enhanced compared to those of PA6/EPM at the same blending composition. After examining the morphology of both blending systems, smaller particile sizes, more homogeneous distribution of domains and improved interfacial adhesion between matrix and domains were observed in the compatibilized system. Mechanical properties such as tensile strength. Young's modulus, flexural strength and modulus, as well as notched and un-notched impact strength of PA6/EPM-g-TAI blends were also found to improve gradually with increasing the content of grafted TAI.

A hydroxyphenyloxadiazole lithium complex as a highly efficient blue emitter and interface material in organic light-emitting diodes

We synthesized a hydroxyphenyloxadiazole lithium complex (LiOXD) as a blue light-emitting and electron injection/transport material to be used in double-layer organic electroluminescent devices. Devices with the concise configuration of ITO/TPD/LiOXD/Al showed bright blue EL emission centered at 468 nm with a maximum luminance of 2900 cd m(-2). A current efficiency of 3.9 cd A(-1) and power efficiency of 1.1 lm W-1 were obtained. LiOXD was also examined as an interface material. The efficiency of an ITO/NPB/Alq(3)/Al device increased considerably when LiOXD was inserted between Alq(3) and aluminium. The improvement of the device characteristics with LiOXD approached that observed with the dielectric LiF salt.

[H2N (C2H4)(2)NH2](4) (H3O) [(PMo2Mo6V4O40)-Mo-V-V-VI-O-IV ((VO)-O-IV)(2)] center dot H2O: A new highly reduced, bicapped pseudo-Keggin vanadylpoly-molybdophosphate

A new vandylpolymolybdophosphate, [H2N(C2H4)(2)NH2](4)-(H3O)[(PMo2Mo6V4O40)-Mo-V-V-VI-O-IV((VO)-O-IV)(2)].H2O, was hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV-vis, XPS, ESR spectra, mid singe crystal X-ray diffraction analysis. The compound contains an unusual highly reduced pseudo-Keggin type polyoxoanion with nine negative charges and exhibits an interesting phosphorus-centered alternate layer arrangement of molybdenum and vanadium oxides.

Study on highly ordered luminescent Langmuir-Blodgett films of heteropolytung state complexes containing lanthanide

Luminescent thin films of heteropolytungstate complexes containing lanthanide (europium or samarium) were successfully fabricated by the Langmuir-Blodgett (LB) technique. The pressure-area isotherm of the monolayer of dimethyldioctadecylammonium. bromide (DODA) is modified rather markedly when the subphase contains the complex of Na9EuW10O36 or Na9SmW10O36. The above results indicate that the monolayer of DODA has a strong interaction with the polyanions of EuW10O369-. (or SmW10O369-). X-ray photoelectron spectra and fluorescent spectra verify that europium and tungsten atoms are 36 36 incorporated into the LB films. Ultraviolet (UV), fluorescent spectra and low-angle X-ray diffraction experiments demonstrate that these LB films have a well-defined lamellar structure. The LB film containing EuW10O369- can give off strong fluorescence 16 on UV irradiation. The characteristic emission behaviors of europium ions in LB films and in the powder of Na9EuW10O369- are discussed. It is found that the intensity ratio of the D-5(0)-F-7(2) transition to the D-5(0)-->F-7(1) transition in LB film is quite different from that in the powder of Na9EuW10O36. The difference of the ratio indicates that the site symmetry of europiurn is distorted in LB film, which is probably due to the strong electrostatic interactions between DODA and polyanions.

Colloid chemical approach to nanoelectrode ensembles with highly controllable active area fraction

A novel "bottom-up" approach to highly controllable nanoelectrode ensembles (NEEs) has been developed using colloidal nanoparticle self-assembly techniques. Ibis solution-based strategy allows flexible control over nanoelectrode size, shape, and interspacing of the as-prepared NEEs. Atomic force microscopy (AFM) was proved to be a powerful tool to monitor the NEE topography, which yields parameters that can be used to calculate the fractional nanoelectrode area of the NEEs. AFM, ac impedance, and cyclic voltammetry studies demonstrate that most of nanoelectrodes on the NEEs (at least by 9-min self-assembly) are not diffusionally isolated under conventional ac frequency range and scan rates. As a result, the NEEs behave as "nanoelectrode-patch" assemblies. Besides, the as-prepared NEEs by different self-assembling times show an adjustable sensitivity to heterogeneous electron-transfer kinetics, which may be helpful to sensor applications. Like these NEEs constructed by other techniques, the present NEEs prepared by chemical self-assembly also exhibit the enhancement of electroanalytical detection limit consistent with NEE theory prediction.