An investigation of the structures and molecular dynamics of natural waxes. II. Carnauba wax

Abstract

For pt.I see ibid., vol.21, p.1421 (1988). Structural aspects and the molecular dynamics of carnauba wax are reported. X-ray diffraction results show that it crystallises in an orthorhombic unit cell. DSC and proton spin-lattice measurements as a function of temperature revealed a premelting solid-solid transition at 335 K. The percentage of carbon atoms in methyl and methylene groups is approximately 12% less than in beeswax, whereas it has a much higher ester and carbonyl content. The average chain length in carnauba wax is 50 carbon atoms. Spin-spin relaxation measurements revealed that the reorientational-translational motion of the chains is much more hindered than in beeswax. The motional parameters associated with the reorientations of the methyl groups have been isolated and compared with these parameters for similar motions in Fischer-Tropsch waxes and beeswax. Spin-lattice relaxation measurements in the rotation frame showed that the activation energy for the dangling motion of the chain ends is approximately 20% higher than in beeswax. The liquid content of the wax has also been determined as a function of temperature by employing a simple pulse technique.