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
✍ Scribed by Ernestina Dubini-Paglia; Antonella Castelli; Pier Luigi Beltrame; Alberto Seves; Bruno Marcandalli
- Publisher
- John Wiley and Sons
- Year
- 1995
- Tongue
- English
- Weight
- 522 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0021-8995
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✦ Synopsis
The aging of bacterial polyester poly(~(-)3-hydroxybutyrate) has been studied by coloring it with 4-diethylamino-4'-methoxyazobenzene and determining the reduction in isomerization rate 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(ethy1ene 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 TB value measured by calorimetric analysis. The kinetics and rate coefficients of aging were determined a t 30°C for the examined polymers. Aging in the copolymer poly(hydroxybutyrate-hydroxyvalerate) was also investigated. 0 1995 John Wiley & Sons, Inc.