Molecular weight distribution from hexane

Some by-product polyethylene waxes have been recently introduced. The feedstock for these materials are mixtures of low molecular weight polyethylene fractions and solvent, generaHy hexane, produced in making polyethylene plastic resin. The solvent is stripped from the mixture, and the residual material offered as polyethylene wax. The products generaHy have a wider molecular weight distribution than the polyethylene waxes synthesised directly, and are offered to markets able to tolerate that characteristic. Some of the by-product polyethylene waxes are distHled under vacuum to obtain a narrower molecular weight distribution. 

Living polymerization with the nickel catalyst enables the block copolymerization of alkoxyallenes [128]. The block copolymers from methoxyal-lene, ethoxyallene, butoxyallene, f-butoxyallene, and phenylallene have narrow molecular weight distributions regardless of the order of the addition of the two monomers. The copolymerization of hydrophilic diethylene glycol allenyl methyl ether and hydrophobic hexyloxyallene forms an amphiphilic block copolymer which is soluble in both water and hexane (Eq. 30). 

The system becomes increasingly complex as the molecular weight rises. Figure 7a and 7b show the distributions of small alkenes and radicals from the decomposition, at 1,040 K, of the series of l-methyl-4-alkyl-cyc/o-hexanes vs. the carbon number (from 1,4-dimethyl-cyclohexane up to l-methyl-4-heptyl-cyclohexane). 

The distribution of the products obtained from this reaction depends upon the reaction temperature (Fig. 5.2-2) and differs from other polyethylene recycling reactions in that aromatics and alkenes are not formed in significant concentrations. Another significant difference is that this ionic liquid reaction occurs at temperatures as low as 90 °C, whereas conventional catalytic reactions require much higher temperatures, typically 300-1000 °C [90j. A patent filed under the Secretary of State for Defence (UK) has reported a similar cracking reaction for lower molecular weight hydrocarbons in chloroaluminate(iii) ionic liquids [91]. An example is the cracking of hexane to products like propene and isobutene (Scheme 5.2-40). The reaction was... 

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