Synthesis and characterization of butadiene-1,3 and octene-1 copolymer prepared by a Ziegler-Natta catalyst based on neodymium
The aim of this work is to evaluate the influence of octene-1 incorporation in the polybutadiene chain on the polymerization reaction and polymer characteristics. Thus, copolymerization of butadiene-1,3 with octene-1 using a Ziegler-Natta ternary catalyst based on neodymium was performed. The weight ratios of butadiene-1,3/α-olefin 100/0, 99/1, 97/3, 95/5, 90/10, 80/20 and 70/30 were evaluated. The copolymers were characterized by size exclusion chromatography (SEC), infrared spectroscopy (FTIR) and thermogravimetric analysis (TG). The results showed that the degradation temperature (Tmax) was not affected by the addition of alpha-olefin, while the thermal behavior has undergone significant changes. The polymer microstructure was not influenced by the increasing of octene-1 content. However, a tendency to molecular mass increase was observed with the increasing of octene-1 content. It was also observed a trend in reduction of the polymerization conversion as the octene-1 content increased.
Copolymerization of ethylene and 1-hexene with Et(Ind)2ZrCl2 in hexane
Abstract Copolymerizations of ethylene and 1-hexene were carried out in hexane at 60°C by using ethylenebis(indenyl)zirconium dichloride as catalyst and methylaluminoxane (MAO) as cocatalyst in presence of triisobutylaluminum (TIBA). The influence of the alkylaluminum concentration and AlTOTAL/Zr molar ratio on the catalyst activity and comonomer incorporation are evaluated. Increasing the TIBA concentration, the MAO solubility augments in the polymerization milieu, as well as the catalyst activity and the comonomer incorporation. Increasing the AlTOTAL/Zr molar ratio, catalyst activity becomes higher, while comonomer incorporation remained constant at around 8 wt% for molar ratios between 0 and 5000. For AlTOTAL/Zr molar ratios higher than 5,000 comonomer incorporation increased gradually. Under the same experimental conditions dimethylsilylbis(indenyl)zirconium dichloride showed higher thermal stability and led to higher comonomer incorporation.
Resource Allocation In R&D Departments
AbstractThis paper examines the problem of allocating funds within research and development organizations, where several departments and multiple research areas must be considered. Furthermore, impacts arising from budget shifts must be measured in terms of various factors or criteria that may be qualitative or quantitative. Using a particular research and development organization, Ontario Hydro, as a backdrop, we develop a framework for evaluating budget changes when (a) multiple criteria, (b) multiple opinions, and (c) qualitative factors are involved. A three stage procedure for budget allocation is proposed. In the first stage, management responses regarding the perceived impacts of budget changes are combined to arrive at a consensus. In stage two, the multiple criteria consensus values are used to derive an overall impact rating for each proposed budget shift pertaining to each of a set of research areas. Finally, in stage three an optimal subset of budget shifts is chosen from the set of all possib...