Sectorization of n-paraffin crystals

Abstract

Orthorhombic monolamellar crystals of n-alkanes with chain length ≥ nC₄₄H₉₀ are found by diffraction contrast electron microscopy to be partitioned into four distinct {110} sectors, just like corrugated polyethylene lamellae. Although images of metal-shadowed crystals do not show gross corrugations, electron diffraction measurements also indicate the different orientations of each sector. Since such a crystal property has been attributed to the presence of chain-end folds, which are clearly absent in these chain-extended crystals, a new explanation for this morphology, perhaps based on preferred high-temperature oblique polymorphs, must be formulated.