Search results for "SUPPORTS"
showing 6 items of 26 documents
Titanium (IV) chloride complexes with salen ligands supported on magnesium carrier: Synthesis and use in ethylene polymerization
2009
The magnesium support with the formula MgCl 2 (THF) 0.32 (Et 2 AlCl) 0.36 was used for immobilization of salen complexes of titanium [Ti(salen)Cl 2 , Ti(salen(O-Me) 2 )Cl 2 ]. The effects of the catalyst composition (i.e. type of titanium complex and type of activator), polymerization temperature, polymerization time, and the effect of comonomer (1-octene) on the activity of the obtained supported catalysts, on the polymer characteristics (molecular weight, molecular weight distribution, melting point), and on the polymer morphology were studied. The findings were compared to those obtained for corresponding unsupported systems. Catalysts immobilization results in considerable changes in ca…
ICT for external use in Croatian four- and five-star hotels
2016
The Purpose – The objective of the paper is to examine the implementation of advanced technology and promotional supports in hotel companies and to compare their performance in four- and five-star hotels. More specifically, ICT for external use are analysed, i.e. customer relationship management (CRM), communication with customers, promotional supports, and online order receptions. Design/Methodology/Approach – The empirical research took place in 38 upscale (26 four and 12 five-star) hotels located in Croatia, in the regions of Dalmatia, Istria, and Kvarner, and in the city of Zagreb. The data were collected through a structured questionnaire administered mainly during personal interviews …
A supported titanium postmetallocene catalyst: Effect of selected conditions on ethylene polymerization
2011
Ethylene polymerization with a titanium complex [N,N-ethylenebis(3-methoxysalicylideneiminato)titanium dichloride] immobilized on the magnesium support with the formula MgCl2(THF)0.32(Et2AlCl)0.36 was studied. In particular, the effects of polymerization temperature, monomer pressure, and polymerization time on the activity of the catalyst and on the polyethylene properties (molecular weight and its distribution, melting point, crystallinity, and bulk density) were evaluated. The findings of investigations prove that the studied supported titanium catalyst is highly active in ethylene polymerization, and its activity increases with increasing temperature and monomer pressure. Moreover, stab…
Vanadium complex with tetradentate [O,N,N,O] ligand supported on magnesium type carrier for ethylene homopolymerization and copolymerization
2010
Immobilization of 1,2‐cyclohexylenebis(5‐chlorosalicylideneiminato)vanadium dichloride on the magnesium support obtained in the reaction of MgCl2·3.4EtOH with Et2AlCl gives a highly active precursor for ethylene homopolymerization and its copolymerization with 1‐octene. This catalyst exhibits the highest activity in conjunction with MAO, but it is also highly active with AlMe3 as a cocatalyst. On the other hand, when combined with chlorinated alkylaluminum compounds, Et2AlCl and EtAlCl2, it gives traces of polyethylene. Moreover, its catalytic activity is strongly affected by the reaction temperature: it increased with rising polymerization temperature from 20 °C to 60 °C. The kinetic curve…
Ethylene polymerization with FI complexes having novel phenoxy‐imine ligands: Effect of metal type and complex immobilization
2011
A series of bis(phenoxy‐imine) vanadium and zirconium complexes with different types of R3 substituents at the nitrogen atom, where R3 = phenyl, naphthyl, or anthryl, was synthesized and investigated in ethylene polymerization. Moreover, the catalytic performance was verified for three supported catalysts, which had been obtained by immobilization of bis[N‐(salicylidene)‐1‐naphthylaminato]M(IV) dichloride complexes (M = V, Zr, or Ti) on the magnesium carrier MgCl2(THF)2/Et2AlCl. Catalytic performance of both supported and homogeneous catalysts was verified in conjunction with methylaluminoxane (MAO) or with alkylaluminium compounds (EtnAlCl3−n, n = 1–3). The activity of FI vanadium and zirc…
The (im)possible success of disadvantaged students. Reflections on education, migration and social change
2019
The paper focuses on the ?unexpected pathways? of successful students with an immigrant background: these biographical routes, that seems socially impossible, raise theoretical issues around the individual-society, actor-structure relationship. Disadvantaged students who succeed represent a sociological challenge in the attempt to understand atypical situations and to identify the institutional processes and the structural opportunities that facilitate them, reducing ethnic inequalities in education. This framework is the starting point of the Su.Per. project (Success in educational pathways of students with immigrant background), based on the collection of written autobiographies of 65 imm…