A new type of disorder affecting the dielectric properties of long-chain esters

The dielectric properties of a series of long-chain esters have been investigated in the solid state. Like other long-chain molecules containing 20 or more carbon atoms, most of the ester molecules showed evidence of hindered molecular rotation about their long axes in the crystal lattice. It was also found that higher dielectric constants resulted when the samples were rapidly frozen than when they were allowed to solidify gradually, the effect being more pronounced as the chain length was increased. In order to explain this behavior, it has been assumed that the esters may crystallize in an ordered lattice in which the dipoles are in a plane, or in a longitudinally disordered lattice in which some at the chains are reversed. In the latter case, the dipoles may or may not form two planes, depending upon the position of, the polar group in the chain. It has also been assumed that the degree of longitudinal disorder increases with increase in freezing rate. Once frozen in, however, it remains fixed until the sample is remelted.