Nano, micro, and bulk structures in atactic polystyrene-syndiotactic polystyrene blends obtained in situ in presence of the CpTiCl3/SiO2/MAO catalysts (Cp-cyclopentadienyl, MAO-methylaluminoxane).

CpTiCl3/SiO2/MAO (Cp=cyclopentadienyl, MAO - methylaluminoxane) catalysts, where the Al:Ti varies from 20:1 to 500:1, were used in styrene polymerization. Atactic - syndiotactic polystyrene blends (aPS-sPS) were obtained in situ, the morphology of which was investigated by means of scanning electron microscopy. The blends morphology changed according to the kind of catalytic centers: cationic and syndiotactic on the catalyst surface, which create individually atactic or syndiotactic polystyrenes forming specific blends containing nano or micro-forms: when the Al:Ti ranges from 50:1 and to 100:1 in the blends, there occur nano-sPS particles 40-120 nm in size, if the Al:Ti≥300:1, the filament of δ-sPS polymorph, is produced where the filament size ranged from 30 to 10 nm.

Hexene-1 isomerization on NaNp/CpTiCl3/Al2O3SiO2 (Np-naphthenide; Cp-cyclopentadienyl) system.

NaNp/CpTiCl(3)/Al(2)O(3)SiO(2) (Cp=cyclopentadienyl; Np=napthenide anion) systems are new catalysts active in the C=C hexene-1 bond isomerization reaction. Their activity depends on amount of titanium[III] hydride surface complexes and the support Lewis acidity. As results showed, all these properties are a function of the Al(2)O(3)-SiO(2) gels composition.

Toluene and chlorobenzene dinitration over solid H3PO4/MoO3/SiO2 catalyst.

A new catalyst, H(3)PO(4)/MoO(3)/SiO(2), was prepared by modification of MoO(3)/SiO(2) using phosphoric acid. The characterization of the catalyst was performed using Infrared and Raman Spectroscopy, potentiometric titration and nitrogen adsorption-desorption methods. Molybdenum oxides were identified along with phosphomolybdic acid and polymolybdates on the modified surface.

Homo-polymerization of alpha-olefins and co-polymerization of higher alpha-olefins with ethylene in the presence of CpTiCl2(OC6H4X-p)/MAO catalysts (X = CH3, Cl).

Cyclopentadienyl-titanium complexes containing -OC6H4X ligands (X = Cl,CH3) activated with methylaluminoxane (MAO) were used in the homo-polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-butene, and 1-hexene, and also in co-polymerization of ethylene with the alpha-olefins mentioned. The -X substituents exhibit different electron donor-acceptor properties, which is described by Hammett's factor (sigma). The chlorine atom is electron acceptor, while the methyl group is electron donor.

Study on the NaNp/CpTiCl3/Al2O3-SiO2 system.

CpTiCl(3)/Al(2)O(3)-SiO(2)/NaNp (Cp=cyclopentadienyl, Np=naphthenide anion) system was obtained by a reduction of cyclopentadienyl titanium[IV] complexes supported on alumina-silica gels with sodium naphthenide in dinitrogen or argon atmospheres. The yield of the reduction reactions and the yield of dinitrogen fixation by the systems reduced in dinitrogen depend on the kind of phases which are present on alumina-silica gel surfaces according to their composition. On hydrolysis the nitrogen titanium complexes obtained liberated ammonia.

Study on the NaNp/Al2O3-SiO2 system.

Sodium naphthenide (NaNp) deposited on aluminosilicate gels yields systems that exhibit signals in EPR spectra, the multiplicity, g values, and intensities of which depend on the gel composition. The symmetrical singlets (I) of a g(1) value of 2.00 were assigned to the complexed naphthalene anion radicals on the centers occurring on the surfaces of the alumina and silica phases of the gels studied.

Isolation and identification of diisopropylnaphthalene isomers in the alkylation products of naphthalene.

GC analysis of diisopropylnaphthalene (DIPN) isomers is presented. Naphthalene was repeatedly alkylated with propylene over an amorphous aluminosilicate catalyst under different preparation conditions, and then pure isomers or at least DIPN fractions enriched in individual isomers were isolated from the alkylates and analysed using GC-MS, IR and NMR techniques. Eight of the ten possible isomers appeared in the chromatograms; seven of them (1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 2,6- and 2,7-) were separated and identified, while the eighth one was indirectly proved to be 2,3-DIPN.

Biomedical engineering programme of the European Community.

The objective of this article is to inform readers of the European Community's programme of work on medical engineering research. An outline of the history of the European Community and its research programme is given. More specific information is then included on the current programme of work and, finally, an Appendix is given naming the national delegates to whom comments can be addressed and from whom further information can be obtained.