Search

Homo- and copolymers of propylene and 1-decene were synthesized by controlled chain-walking (co)polymerization using phenyl substituted &alpha, diimine nickel complexes activated with modified methylaluminoxane (MMAO). This catalytic system was found to polymerize propylene in a living fashion to furnish high molecular weight ethylene-propylene (EP) copolymers. The copolymerizations proceeded to give high molecular weight P/1-decene copolymers with narrow molecular weight distribution (Mw/Mn &asymp, 1.2), which indicated a living nature of copolymerization at room temperature. The random copolymerization results indicated the possibility of precise branched structure control, depending on the polymerization temperature and time.

A promising production route for a high-quality base stock for lubricants is the oligomerization of high molecular-weight olefins in a high energy efficiency system. Oligomerization of 1-decene (C10) was conducted in a microwave-assisted system over a HY zeolite catalyst at different reaction temperatures and times. Higher reaction temperature resulted in increasing formation of dimers and trimers. The oligomerization reaction yielded 80% conversion, 54.2% dimer product, 22.3% trimer product and 3.4% heavier product at 483 K for a reaction time of 3 h. The best fit kinetic model for the dimerization reaction was formulated from an assumption of no vacant reaction sites. For the trimerization reaction, a molecule of dimer (C20) formed on the active site, interacted with a molecule of 1-decene in the bulk solution to form a molecule of trimer (C30). Apparent activation energies for the dimerization and trimerization reactions were 70.8 ± 0.8 and 83.6 ± 0.9 kJ/mol, respectively. The C13-NMR spectrum indicated that the oligomer product contained a significant portion of highly branched hydrocarbons, causing a substantial reduction in the viscosity index compared to conventional poly-alpha olefin lubricant (PAO).

The focus of this paper is to establish a lumped kinetic scheme for secondary reactions of tar produced from pyrolysis of plastics or polymer-based wastes. Notably, the focus is not on the detailed yield of all reaction intermediates and products but on the propensity to form soot. Based on the assumption that that primary tar from pyrolysis of plastic wastes is mostly formed by aliphatics which can undergo progressive aromatization to polycyclic aromatic hydrocarbons (PAHs) and soot, a reaction network with 198 species and 6307 reactions proposed by Ranzi and coworkers was lumped into a very simple five reaction mechanism. The lumped kinetic model has been used to predict PAHs and soot formation in different conditions and proved to be a good alternative to comprehensive kinetic models up for relatively low temperature and short residence times (of up to 1 min at 1200 K, up to 1 s at 1400 K). At higher temperature/longer residence times, the simplified model still provides reasonable qualitative trends but the amount of PAHs and soot is underestimated. The timescale of aromatization under inert conditions appears similar for all the alkanes and alkenes examined and also the yields in main reaction products seem to scale well with the number of carbon and hydrogen atoms of the parent alkane/alkene. Evolution of the young aliphatic tar into large aromatics is prevented as long as gaseous oxygen being available for oxidation. The lumped kinetic model has been used to highlight the effect of different modes of oxygen feeding and of incomplete mixing of fuel and oxygen on the formation of PAH and soot.

Polymerizations of 1-decene (DC), 1-dodecene (DD), and 1-tetradecene (TD) by Cp*TiMe2(O-2,6-iPr2C6H3) (1)&ndash, [Ph3C][B(C6F5)4] (borate) catalyst have been explored in the presence of Al cocatalyst. The polymerizations of DC and DD, in n-hexane containing a mixture of AliBu3 and Al(n-C8H17)3, proceeded with high catalytic activities in a quasi-living manner, affording high molecular weight polymers (activity 4120&ndash, 5860 kg-poly(DC)/mol-Ti&middot, h, Mn for poly(DC) = 7.04&ndash, 7.82 &times, 105, after 20 min at &minus, 30 &deg, C). The PDI (Mw/Mn) values in the resultant polymers decreased upon increasing the ratio of Al(n-C8H17)3/AliBu3 with decreasing the activities at &minus, C. The PDI values also became low when these polymerizations were conducted at low temperatures (&minus, 40 or &minus, 50 &deg, C), high molecular weight poly(DD) with low PDI (Mn = 5.26 &times, 105, Mw/Mn = 1.16) was obtained at &minus, C. The TD polymerization using 1&ndash, borate&ndash, AliBu3 catalyst (conducted in n-hexane at &minus, C) afforded ultrahigh molecular weight poly(TD) (Mn = 1.02 &times, 106, Mw/Mn = 1.38), and the PDI values also decreased with increasing the Al(n-C8H17)3/AliBu3 ratio.

We synthesized polyethylene (PE), poly(ethylene-co-1-decene), poly(ethylene-co-p-methylstyrene) and poly(ethylene-ter-1-decene-ter-p-methystyrene) using a rac-Et(Ind)2ZrCl2 metallocene catalyst and a methylaluminoxane cocatalyst system. The materials were characterized using nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. We compared and studied the kinetics, thermal properties and mechanical ones of these polymers. Tg was related to the amorphous phase of the polymers, whereas the tensile strength and storage modulus (E’) were related to the crystalline phase. We also found that PE has the highest crystallinity through differential scanning calorimetry and wide-angle X-ray scattering analysis. The polymerization rates of poly(ethylene-co-1-decene) and poly(ethylene-ter-1-decene-ter-p-methystyrene) were always higher than that of polyethylene.