Molecular Structure, Crystallization and Morphology of Very Low Density Polyethylene (VLDPE)
The heterogeneous ethylene/l-octene copolymer studied crystallizes from 120 to −60 °C and melts from −60 to 130 °C, as shown by DSC measurements. At −60 °C, the enthalpy-based weight crystallinity is 37 %, and at 23 °C it amounts to 25 %. The results of fractionation experiments strongly suggest that the heterogeneity is intermolecular in nature and that VLDPE is actually a reactor blend of molecules ranging from the uncrystallizable type to the HDPE type. The morphology, as investigated by electron microscopy, confirms this conclusion. It is characterized by regions of highly different crystallinity, ranging from structureless regions to compact semi-crystalline domains, and by lamellar crystallites of varying size.
KeywordsHeating Curf Heat Curf Heat Capacity Curve Ethylene Copolymer Appreciable Portion
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- 1.Mathot, V.B.F. and Pijpers, M.F.J., Structure and crystallization of homogeneous and heterogeneous ethylene copolymers including very low density polyethylenes. In Integration of Fundamental Polymer Science and Technology, Proceedings of International Discussion Meeting, Rolduc Abbey, Netherlands, April 26–30, 1987. Elsevier Applied Science Publishers Ltd, London, 1988, pp. 381–4.Google Scholar
- 2.Barham, P.J., Hill, M.J., Keller, A. and Rosney, C.C.A. These Proceedings.Google Scholar