Polyethylene from propylene

Tracer studies have been used in an attempt to determine the nature of the ends of the chain but these were as unsatisfactory as for propylene. Feldman and Perry (83) used triterated methanol to react the polyethylene from a titanium tetrachloridetrialkylaluminum catalyst. They found a continual increase in the number of polymeric chain ends which react with the tritium. This agrees with the results of Roha and Beears (84) who showed the very rapid exchange of alkyls which took place when ethylene was grown on a Ziegler catalyst in the presence of excess alkylaluminum chloride. In these experiments only an extremely small... 

Steam cracking of various petroleum fractions is gaining widespread use for the production of olefins. These olefins are produced essentially for use as feed stock for numerous petrochemical processes, but the by-product butylenes and propylenes are sometimes used as feed stock for aviation and motor alkylation units. Ethylene is the most important of the olefins produced from this type of cracking, and propylene is second in importance. These two olefins are normally charged to either alkylation or polymerization units for the production of petrochemicals or petrochemical intermediates. Polyethylene and propylene dimers, trimers, tetramers, and penta-mers are some of the more important polymers produced, while ethybenzene, dodecylbenzene, cumene, diisopropylbenzene, and alkylated... 

Bottles made of plastic materials are better avoided for storage, since the solvent is capable of leaching a plasticizer out from the bottle. For rapid transfer, however, polyethylene or -propylene pipettes, measuring cylinders, etc. can be used with apparently no detrimental effects. 

A block copolymer system of PVC and polyethylene -co-propylene) (EPM) resulting from ultrasonic irradiation, has been investigated (248). 

Ethylene for polymerization to the most widely used polymer can be made by the dehydration of ethanol from fermentation (12.1).6 The ethanol used need not be anhydrous. Dehydration of 20% aqueous ethanol over HZSM-5 zeolite gave 76-83% ethylene, 2% ethane, 6.6% propylene, 2% propane, 4% butenes, and 3% /3-butane.7 Presumably, the paraffins could be dehydrogenated catalyti-cally after separation from the olefins.8 Ethylene can be dimerized to 1-butene with a nickel catalyst.9 It can be trimerized to 1-hexene with a chromium catalyst with 95% selectivity at 70% conversion.10 Ethylene is often copolymerized with 1-hexene to produce linear low-density polyethylene. Brookhart and co-workers have developed iron, cobalt, nickel, and palladium dimine catalysts that produce similar branched polyethylene from ethylene alone.11 Mixed higher olefins can be made by reaction of ethylene with triethylaluminum or by the Shell higher olefins process, which employs a nickel phosphine catalyst. 

Nevertheless, in addition to syntheses by Marvel and Mayo, one of my classmates. Dr. Grant Baily working with L.S. Reid produced low molecular weight polyethylene by passing ethylene over a nickel oxide/silica-alumina catalyst. These investigators also made solid polypropylene from propylene via the same route in 1945. Chemists at Shell... 

Wunderlich et al. have also reported the preparation and sepeiration of extended chain crystals of polyethylene from the melt at 510 K and 500 MN m" and separating them by etching with fuming nitric acid. The product was, of course, an a,(o-dicarboxylic acid with a molecular length of about 900 —CH — units. Cavello et have grown crystals of random isotactic copolymers of propylene and but-l-ene from isoamyl acetate solution. By comparison with melt-crystallized materials they concluded that both morphologies, and hence crystallizations, were fundamentally identical, and that the co-monomer unit co-crystallizes. There is a depression of the melting point over that of the homopolymer and a eutectic is observed at 48% butene content. 

Figure 6.2 Example of appearance of multi-modality during thermal degradation in water of polyethylene oxide - propylene oxide - ethylene oxide. Reproduced with permission from S. Karlsson, Polymer News, 2002, Ll, 305. 2002, Gordon...

It should be noted that the formation of the filler structural lattice in thermoplastics can also affect the viscoelastic properties (143). The viscoelastic properties of and PMMA filled with aerosil and glass fiber have been examined in (149) in which the role of the filler and polymer nature was demonstrated as well as their interaction in response to those properties. The dynamic properties of filled polyethylene, poly-propylene, and of a number of other polymers have been investigated in (72) where they are treated from the point of view of changes in the molecular mobility. A nundier of other reports on those problems have been published (145-148). The principal findings of these studies confirm our concepts related to effects of molecular mobility on the viscoelastic properties. However, in contrast to the studies of filled resins, the filled thermoplastics were examined only by the use of common... 

Another subclass of substituted amides that is of great commercial value is the ethoxylated amides. They can be synthesized from alkanolamides by chain extending with ethylene or propylene oxide or by ethoxylation directly from the primary amide (46—48). It was originally beheved that the stepwise addition of ethylene oxide (EO) would produce the monoethano1 amide and then the diethanolamide when sufficient ethylene oxide was added (49), but it has been discovered that only one hydrogen of the amide is substituted with ethylene oxide (50—53). As is typical of most ethylene oxide adducts, a wide distribution of polyethylene oxide chain length is seen as more EO is added. A catalyst is necessary to add ethylene oxide or propylene oxide to a primary or an ethoxylated amide or to ethoxylate a diethoxy alkanolamide synthesized from diethanolamine (54). 

Natural mbber comes generally from southeast Asia. Synthetic mbbers are produced from monomers obtained from the cracking and refining of petroleum (qv). The most common monomers are styrene, butadiene, isobutylene, isoprene, ethylene, propylene, and acrylonitrile. There are numerous others for specialty elastomers which include acryUcs, chlorosulfonated polyethylene, chlorinated polyethylene, epichlorohydrin, ethylene—acryUc, ethylene octene mbber, ethylene—propylene mbber, fluoroelastomers, polynorbomene, polysulftdes, siUcone, thermoplastic elastomers, urethanes, and ethylene—vinyl acetate. 

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