A set of new chromium(III) [Cr(III)] complexes based on the tridentate ligand HC(Pz)2Py (Pz = pyrazole; Py = pyridine) and its derivatives were prepared, characterized, and evaluated for ethylene polymerization/oligomerization. X-ray single-crystal analyses of the Cr(III) complexes showed tridentate coordination on the fac-octahedral Cr sphere. Upon activation with methylaluminoxane (MAO), the ...

EEthylene polymerization catalysts became available in an enormous variety. The challenge in this research is to find catalysts that are able to connect ethylene molecules in such a way that not only linear chains are produced but variations like branched materials that possess very interesting mechanical properties like linear low density polyethylene (LLDPE). In this contribution, three diffe...

The slurry polymerization of ethylene was studied by employing a (TiCl4/Mg(OEt)2/TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, Mv, were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and Mv were achieved at 60 °C. The concentrat...

This study demonstrates the preparation, structure, and properties of polymer-impregnated wood (PIW) based on novel Muchelia macclurei wood through the in-situ polymerization of vinyl and functional monomers. Mixed monomers of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EGDMA) (2:1 molar ratio) were effectively vacuum/pressure impregnated into the cellular structure of the f...

Hydrosilane-B(C6F5)3 adducts were found to activate zirconocene dihalides and generate ternary catalytic systems possessing moderate to high activity in ethylene polymerization to high density polyethylene (HDPE). The activation efficacy of the adducts increased with increasing hydride donor ability and decreased with steric crowding of the particular hydrosilane used. NMR investigation of the ...

We give a detailed account on the enzymatic synthesis of RNA conjugates by T7 RNA polymerase using modified initiator nucleotides during transcription. Following two different routes, ternary conjugates of guanosine-5'-monophosphate, poly(ethylene glycol), and anthracene were synthesized via phosphoramidite intermediates and characterized by a variety of spectroscopic techniques. Up to a degree...

A new heterogeneous catalyst for CO(2) activation was identified in the Cr(II)/SiO(2) Phillips catalyst, one of the most important catalysts used industrially for olefin polymerization. Interestingly, it was found that Cr(II)/SiO(2) strongly activates CO(2) already at room temperature, making it available for chemicals synthesis. A preliminary attempt in this direction was done by following the...

Ethylene-propylene-diene rubbers (EPDM) are one of the most important polyolefin materials widely commercialized and used in various industries recent years. The production EPDM is based solely on catalytic coordination polymerization processes. development new catalysts processes for synthesis has expanded range products their manufacturing terms energy efficiency, processability, environmenta...

in this study, the slurry polymerization of ethylene over ticl4/mgcl2/alet3 was obtained. firstly, to obtain the optimum value of [al]/[ti], the effect of [al]/[ti] on polymerization rate and catalyst yield was studied. also, the effect of catalyst content on yielding, crystallization, melting point and density of product were obtained. to determine the order of reaction, the monomer pressure w...