Polyethylene, preparation

Antioxidants. The 1,2-dihydroquinolines have been used in a variety of ways as antioxidants (qv). For example, l,2-dihydro-2,2,4-trimethylquinoline along with its 6-decyl [81045-48-9] and 6-ethoxy [91-53-2] derivatives have been used as antio2onants (qv) and stabilizers (68). A polymer [26780-96-1] of l,2-dihydro-2,2,4-trimethylquinoline is used in resins, copolymers, lubricant oils, and synthetic fibers (69). These same compounds react with aldehydes and the products are useful as food antioxidants (70). A cross-linked polyethylene prepared with peroxides and other monomers in the presence of l,2-dihydro-6-ethoxyquinoline produces polymers with a chemically bonded antioxidant (71). 

Fig. 11 Molecular weight (Mn) and molecular weight distribution, M IM, of polyethylene prepared with 17 using DEZ as CSA as a function of polymer yield...

In addition to these studies on the branched polyethylene, fractions of linear polyethylene prepared by large-scale gel-permeation chromatography are being characterized for certification in the near future. These should be useful for gel-permeation chromatography calibration. We also expect them to be particularly valuable in dilute solution, crystallization, and rheological studies. 

The crystallinity of polyethylene prepared by coordination polymerization can be decreased in a controlled fashion by the addition of a small amount of another alkene, such as 1-pentene. Show the structure of the resulting polymer and explain why its crystallinity is reduced. 

Weibullian/sine function is introduced. Applications of this method to polyethylenes prepared by various conditions successfully explain the morphology and physical properties. Crystallisation mechanism of nylon 46 by high-resolution NMR in the solid state is also introduced. 

Measurement of the molecular mass distribution of polyethylene prepared on... 

An essential difference is observed for the chain transfer with hydrogen in the polymerization on bulk TiClj (the chain transfer is 0.5th order with respect to [Hj]) and on catalysts supported on MgClj (first — order chain transfer with respect to [Hj]). This difference leads to higher values of the melt index of polyethylene prepared on the TiClyMgClj catalyst in the presence of H in comparison with non-supported titanium chloride catalysts... 

The two types of active centres, were confirmed in that the first peak, which is found in the zone of low molecular weights in the MWD curve, for polyethylene prepared with (CjH5)2TiCl2—A1(C2H5)2C1, pratically coincides with the position of the single peak obtained with the blue complex -Al(C2H5)2Cl catalytic system. A similar... 

Taylor and Tung reached the same conclusions for polyethylene prepared with TiCl4—Al(i-C.jH,)3, Keii for polypropylene prepared with MgClj-supported... 

Meyer and Reichert found that, for polyethylene prepared at 80 °C with the highly active Mg(OCjH5)2—TiCl and AlRj catalytic system, the MWD is practically independent of conversion and of both catalyst and polymer particle size, yet it broadens with an increase in catalyst concentration. 

Wang, W.-J. Kharchenkob, S. Miglerb, K. Zhu, S. Triple-detector GPC characterization and processing behavior of long-chain-branched polyethylene prepared by solution polymerization with constrained geometry catalyst. Polymer 2004, 45 (19), 6495-6505. 

In a similar way, n-butyl acrylate was copolymerized by ATRP with methacrylate macromonomers containing highly branched polyethylene prepared by Pd-catalyzed living ethylene polymerization. The observed reactivity ratios depend on the molecular weight and concentration of the macromonomer. The resulting graft copolymers showed microphase separation by AFM [304]. 

Fig. 1. Illustrative molecular weight distributions of polyethylene prepared by soluble vanadium and heterogeneous titanium catalysts...

Fio. 17. The molecular weight distribution of high-density polyethylenes prepared by soluble and insoluble catalysts. The difference in molecular weight distribution is indicated by the difference in slope of the lines. 

A maleated ester of low density polyethylene, prepared by the reaction of LDPE and dibutyl maleate in solution, was blended with TPS by reactive extrusion. Mechanical properties of the blends were similar to those of the LDPE due to the compatibilization of these dissimilar components [75]. 

Previous measurements of diffusion in polyethylene (37, 38) have found a diffusion coefficient decreasing with increasing crystallinity. These results were explained by assuming an increased tortuosity with increased crystallinity. These investigators have compared samples of polyethylene prepared by different manufacturers under different conditions. For their samples the increase in crystallinity may be the result of more crystallites of a smaller size, increasing both the tortuosity and the chain immobilization factor. 

Noninterfering anions covalently bound to polymers have been prepared by the AIBN-initiated copolymerization of styrene with trialkylammonium 4-styryltris(pentafluorophenyl)borate (Scheme 30). High-density polyethylene prepared from Cp2ZrCl2— Al(i-Bu)3 and this activator shows no signs of reactor fouling in a slurry polymerization. "... 

J. Schauer and L. Brozova. Heterogeneous ion-exchange membranes based on sulfonatedpoly(l,4-phenylene sulfide) and linear polyethylene Preparation, oxidation stability, methanol permeability and electrochemical properties. J. Membr. Set, 250(1-2) 151-157, March 2005. 

Polyethylene prepared in this way may have as many as 20 to 30 short branches per 10,000 caibon atoms in the chain and one or two long-chain branches per molecule, due to backbiting ... 

A Japanese patent issued to Watanabe and Okamoto [301] describes preparation and illustrates an iron containing catalyst for polyethylene preparation. It is shown here as an illustration ... 

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