Low density linear polyethylene LDLPE

Low density linear polyethylene (LDLPE), 20 201. See also Linear low density polyethylene (LLDPE)... 

M.A. Smith, E.A. Benham, C.M. Didier, M.P. McDaniel, J. Ratzlaff, W.M. Whitte, in Novel Low-density Linear Polyethylene (LDLPE) Made Via the Phillips Process, MAACK Conference, Zurich, Switzerland, 1993, Oct. 5. 

The development of bifunctional catalysts for specific catalytic sequences of reactions in which the product of the first reaction can serve as substrate for the second is of great importance. There are many examples of such reactions. They are, for instance, the monomer-isomerizing polymerization of heptene-2, heptene-3 and 4-methyl-2-pentene and the combination of propene disproportionation with oligomerization, etc. Bifunctional catalysts are most widely used for ethylene copolymerization with a-butene in situ in the production of so-called low-density linear polyethylene (LDLPE). All general methods for LDLPE production are based on incorporation into a PE backbone of short-chain branches, which can be made by catalytic copolymerization of ethylene with a-olefins C3-C10. A macromolecnlar ligand offers wide possibilities of joining the different types of active site in the same matrix (see also Section 12.5.2). 

When comonomers are introduced, this destroys chemical regularity of chain units. It thereby reduces or even eliminates crystallinity, depending on the comonomer content. An illustration which is also important in applications is provided by ethylene copolymers. If propene is introduced into polyethylene, the level of crystallinity is reduced (therefore also diminishing its modulus and density). This is because it limits the possibilities for a crystalline structure to those sequences made up of (CH2)i units. A whole family of new compounds, called Low Density Linear PolyEthylenes (LDLPE), was developed during the 1980s. Ethylene/propene (50/50) copolymers form amorphous compounds which are used as elastomers (EPDM). 

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See also in sourсe #XX -- [ ]

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