The results of experimental investigations of poly(butylene terephthalate)-
dimerized fatty acid (PBT-DEA) elastomers using dilatometric measurements,
dielectric spectroscopy as well as ultrasonics are presented. Relaxation pr
operties of the polymers are characterized in relation to the degree of cry
stallization of the hard segments. The variation of the polymer properties
with temperature has been ascribed to two relaxation processes glass transi
tion (alpha-relaxation) and second order (beta-transition) of the soft phas
e of elastomers.