Linear low-density polyethylene is a semicrystalline ethylene copolymer in which short alkyl branches are introduced by copolymerising ethylene with an alpha-olefin, keeping the chain backbone essentially linear [1]. Branch content and branch length set the crystallinity, since the branches are excluded from the lamellae and act as defects that thin the crystals and lower the melting range [2]. The result is a density between that of low-density polyethylene, which carries long-chain branching, and high-density polyethylene, which is nearly unbranched, with a stiffness that falls as branch density rises [3]. Its melt rheology reflects the absence of long-chain branching, so the flow activation energy is lower than in a branched homopolymer of the same molar mass [2].
- ethylene copolymer
- short-chain branching
- semicrystalline polymer
- alpha-olefin
- lamellar crystal
Synthesis and properties of polymers·Polymers and Plastics·Materials Science·Physical Sciences
References
- Wagner, M.H.; Analysis of time-dependent non-linear stress-growth data for shear and elongational flow of a low-density branched polyethylene melt. Rheologica Acta 1976, 15, 136-142, 10.1007/bf01517505.
- Hotta, S.; Paul, D.; Nanocomposites formed from linear low density polyethylene and organoclays. Polymer 2004, 45, 7639-7654, 10.1016/j.polymer.2004.08.059.
- Galland, G.B.; de Souza, R.F.; Mauler, R.S.; Nunes, F.F.; 13C NMR Determination of the Composition of Linear Low-Density Polyethylene Obtained with [η3-Methallyl-nickel-diimine]PF6 Complex. Macromolecules 1999, 32, 1620-1625, 10.1021/ma981669h.