Ethylene-l-hexene

A comparative study ethylene/l-hexene copolymerization with [t-BuNSiMe2Flu]TiMe2 catalyst via various activators... 

Table 1. Rraadts of polymerization of ethylene/l-hexene poljmerization with catalyst U...

According to the ethylene consumption rate profile for ethylene/l-hexene copolymerization in figure 1, it indicated that deactivation of active species occurred in the borate system. On the... 

In subsequent investigation by the authors (1) other high-activity monocyclo-pentadienyl complexes were prepared, (I), and used in the preparation of polyethylene and poly(ethylene-l-hexene). 

Polymer "B" is an ethylene-l-hexene copolymer by design. A flow activation energy of 9.6 kcal/mol suggests that long chain branching may be present. The C-13 NMR spectrum, however, is complicated by the presence of butyl branches as in the case of... 

The most relevant E/O co-polymerization reports with rzmzz-Cp-amido titanium complexes include ethylene/1-butene,537,538 ethylene/l-hexene,539,540 and ethylene/l-octene.91,442,454,456,457,464,506,541 Ethylene/4-methyl-l-pen-tene co-polymerizations have been reported as well.457,542 The thermal and physical properties of the octene co-polymers produced with ansa-G -amido titanium complexes have been studied.543-546 The importance of the activator has been pointed out in many instances.91,108... 

Since quantitation is crucial in many polymer analyses, it is important to obtain data with T l and NOE in mind. Highly flexible polymers undergoing rapid segmental motion typically give narrow l c lines. Often these carbons can have Tj s of several seconds and full or nearly full NOE. Other, more rigid polymers may exhibit broad lines and little NOE. In the case of ethylene-l-hexene copolymer there is considerable NOE for the 1-hexene portion (Figure 2). Relative peak areas can produce good concentrations only if and NOE are properly considered. ... 

Relaxation Time and Nuclear Overhauser Effects. It is well known that for 90° pulse angles, a pulse spacing of 5 x Ti will ensure that 99% of rf excited nuclei will be fully relaxed between pulses (14). Such pulse spacings will ensure reliable quantitative results and are recommended although it is possible to obtain quantitatively reliable results with lower pulse angles. The following relaxation time (Ti) data was obtained for a 97/3 ethylene-l-hexene copolymer ... 

Relative Peak Heights and Integrated Areas from 50.3 MHz 13c NMR Spectra of a 97/3 Ethylene-l-Hexene Copolymer Utilizing Different Pulse Angles and Pulse Spacings. 

Figure 5 A 50.3 MHz 13c NMR Spectrum of an 83/17 Ethylene-l-Hexene Copolymer at 125°C and 15% by Weight in 1,2,4-Trichlorobenzene...

Figure 7 Run Number Versus Density for a Series of Ethylene-l-Butene, Ethylene-l-Hexene and Ethylene-l-Octene Copolymers...

One final area for discussion is the use of NMR for the determination of polymer number average molecular weights. End group resonances were clearly visible in the 13c NMR spectrum of the ethylene-l-hexene copolymer in Figure 3. An opportunity to determine polymer degrees of polymerization or number average molecular weights should not be overlooked. 

Figure 10 Run Number Versus Tensile Strength at Yield for a Few Ethylene-l-Hexene and Ethylene-l-Butene Copolymers...

Polymer (B) ethylene/l-hexene copolymer 1999KIN, 2001DOE... 

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