A comparison of the dielectric dispersion behavior of corn amylose and amylopectin acetates

The dielectric constants and loss factors of disks of corn amylose and amylopectin triacetates, unplasticized and plasticized with 15% by weight of dioctyl phthalate, dimethyl phthalate, and diphenyl were measured at ten frequencies throughout the range 102 to 105 c.p.s. over the temperature interval of −78 to 80°C. A two‐terminal dielectric cell constructed from stainless steel and Teflon is described which may be thermostated by direct immersion into liquid baths. The values of ΔE*, ΔS*, and ΔF* for the dielectric relaxation processes occurring in each of the eight systems were calculated from the variation with frequency of the temperature at which the maximum values of the loss factors are found. The similarities and differences which are present in the dielectric dispersion data are discussed in terms of the molecular structures of amylose and amylopectin acetates, and possible mechanisms are suggested to explain the observed behavior.