The rectangular crystal packing of methyl-branched paraffins in their orthorhombic forms is studied systematically by electron diffraction to show that, irrespective of branch position on the chain, a close interaction of chain double rows occurs, placing the branch in the space between two chain ends. If the chain branches occur near the ends, the structure can slowly rearrange into a true bilayer. If the branch occurs near the center, then there are a large number of intermediate "nematocrystalline" disordered forms that are possible before the final ordered layered packing.
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