[gamma]-radiation-induced changes in the chemical and physical structure of poly(ethylene terephthalate)
Poly(ethylene terephthalate) (PET) film was irradiated with [gamma]-rays in air at doses from 0 to 620 Mrad, and at the rate of 0l8 to 1.0 Mrad/hr. Radiation-induced physical structure changes were studied by DMA and DSC measurements. Tensile properties were measured to find interrelationships with chemical and physical structure changes. Below 100 Mrad, PET shows little change in NMR and IR spectra. Fluorescence emission spectra, however, show the presence and increase of monohydroxy-substituted phenylene groups. This hydroxylation appears to stabilize the polymer. The phenylene group in PET also contributes to radiation-resistance. The amorphous-crystalline interfaces impede the penetration of oxygen and slow the oxidative chain scission. Between 100 and 215 Mrad, UV studies reveal that the rates of reaction begin to change rapidly. Chain scission appears to take place first in the interspherulitic amorphous regions and then in the intraspherulitic (interlamella) regions. [gamma]-Radiation-induced oxidative degradation shows aspects of both photolysis and of thermooxidative degradation (proton and carbon-13 NMR, and IR studies). It was concluded that the crystalline phase breaks down in to smaller crystallites, and these smaller crystallites grow in size by acting as nucleating sites. Tensile measurements show that throughout the range of irradiation studied the tensile strength at break and the percent elongation decrease. The tensile strength decreases uniformly and the percent elongation exhibits a more rapid decrease above 100 Mrad. The results of this study lead to the conclusion that [gamma]-radiation-induced oxidative degradation of PET involves products that are seen in both photolysis and thermooxidation.
- Research Organization:
- Massachusetts Univ., Lowell, MA (United States)
- OSTI ID:
- 5089836
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
POLYETHYLENES
CHEMICAL RADIATION EFFECTS
PHYSICAL RADIATION EFFECTS
TEREPHTHALIC ACID
GAMMA RADIATION
OXIDATION
TENSILE PROPERTIES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DICARBOXYLIC ACIDS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MECHANICAL PROPERTIES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
RADIATION EFFECTS
RADIATIONS
360605* - Materials- Radiation Effects