In this study, a mathematical model for the time evolution of molecular weight distribution (MWD) was developed. This temporal is based on well-known Ziegler–Natta polymerization mechanism and reaction kinetics by parametric solving related differential equations. However, due to generality reactions involved, can be extended other type catalysts, such as metallocenes, Phillips, etc. The superi...

Although Ziegler–Natta (ZN) catalysts play a major role in the polyolefin market, true understanding of their properties at molecular level is still missing. In particular, there lack knowledge on electronic Ti sites. Theoretical calculations predict that electron density sites precatalysts correlates with activation energy for olefin insertion Ti-alkyl bond generated these after by Al-alkyls. ...

Ab initio SCF-LCAO-MO all-electron calculations have been performed for the catalyzed reaction, related to the Ziegler-Natta polymerization process TiCl.·Al(CH3)3+C2H. -+TiCl •. Al(CH3h·C3H7. The energy of the Ti-Al--ethylene complex during the reaction pathway is associated to the following processes: First, the ethylene coordinates to the catalyst complex and subsequently it reacts with the m...

In the previous studies, the several halocarbons (HC) were tested as promoters for a Ti-based Ziegler-Natta (ZN) catalyst at different polymerization conditions. The Results showed that chloro cyclohexane has the best operation in catalyst activity, polymer particle size growth, hydrogen responsibility and wax reduction too. For the first time in this study, the effect of Al/Ti ratio on the opt...

Aluminum, the third most abundant element on the earth’s crust, occurs predominantly in oxidic and silicatic minerals. It was first obtained in a pure elemental form by F. Wöhler in 1827 by the reduction of AlCl3 with elemental potassium. In 1859 W. Hallwachs and S. Schafarik synthesized the first organoaluminum compound Et3Al2I3 from elemental Al and EtI, but it took almost 100 years before K....

Modeling and Simulation of an Emulsion Copolymerization Process Sabrina Copelli*, Mario Dente, Marco Derudi, Giulia Bozzano, Vincenzo Torretta Università degli Studi dell’Insubria Dip. di Scienza e Alta Tecnologia Via G.B. Vico 46 21100 Varese Italy b Politecnico di Milano Dip. di Chimica, Materiali e Ingegneria Chimica “G. Natta”P.za Leonardo da Vinci 20133 Milano Italy sabrina.copelli@uninsub...

We have been engaged in a search for coordination catalysts for the copolymerization of polar monomers (such as vinyl chloride and vinyl acetate) with ethylene. We have been investigating complexes of late transition metals with heterocyclic ligands. In this report we describe the synthesis of a symmetrical bis-thiadiazole. We have characterized one of the intermediates using single crystal X-r...

A method for the determination of Ti and V using inductively coupled plasma atomic emission spectrometry (ICP OES) in Ziegler-Natta polymerization catalysts is proposed. The concentrations of both Ti and V are efficiently determined after catalyst acid digestion with a mixture of HNO3 + HCl + HF and heating (160 degrees C for 6 h) or with 10% (v/v) H2SO4 and heating (160 degrees C for 6 h) or w...