THERMAL CIS-TRANS ISOMERIZATION OF 4-DIETHYLAMINO-4'-METHOXYAZOBENZENE IN POLY(D(-)3-HYDROXYBUTYRATE) AND ITS HYDROXYVALERATE COPOLYMER AS A PROBE FOR CHARACTERIZING THEIR AGING

摘要

The aging of bacterial polyester poly(D(-)3-hydroxybutyrate) has been studied by coloring it with 4-diethylamino-4'-methoxyazobenzene and determining the reduction in isomerization fate of the dye with aging, such a reduction being a measure of the loss in polymer sequential mobility that is responsible for the considered phenomenon. A preliminary test carried out on poly (ethylene terephthalate) colored with 4-diethylaminoazobenzene proved the isomerization of the dispersed dye to be a sound probe for determining the aging process. In the case of the bacterial polyester, the aging process appeared even above the polymer T-g value measured by calorimetric analysis. The kinetics and rate coefficients of aging were determined at 30 degrees C for the examined polymers. Aging in the copolymer poly(hydroxybutyrate-hydroxyvalerate) was also investigated. (C) 1995 John Wiley and Sons, Inc. [References: 28]