An investigation of the structures and molecular dynamics of natural waxes. I. Beeswax

Abstract

A detailed NMR investigation, supported by DSC and X-ray diffraction measurements, of the combwax of the African bee apis mellifera adansonii is reported. Proton spin-lattice relaxation times in the laboratory and rotating frames, as well as the proton spin-spin relaxation time, have been measured as a function of temperature (333 K>T>110 K). The liquid content of the wax has also been determined as a function of temperature by employing a simple pulse technique. The motional parameters associated with the reorientations of the methyl groups and the chains have been isolated and compared with these parameters for similar motions in Fischer-Tropsch waxes. The T1 rho results revealed a minimum which is associated with the dangling motion of chain ends in the amorphous zone of the wax. The relaxation results strongly suggest that beeswax is branched to a much higher degree than Fischer-Tropsch waxes, including oxidised waxes. The high-resolution 13C spectrum of beeswax in the solid state shows that it resembles oxidised Fischer-Tropsch hard wax closely. The major difference is that a higher percentage of carbon atoms are involved in ester groups in beeswax. Oxidised hard wax contains a higher fraction of carbon atoms with double carbon-carbon bonds. The average chain length in beeswax, determined by ebullioscopic methods, is 40 carbon atoms.