DYNAMIC MECHANICAL BEHAVIOR OF IRRADIATED POLYETHYLENE

Journal Article · Wed Oct 01 04:00:00 EDT 1958 · Journal of Applied Physics (U.S.)

DOI:https://doi.org/10.1063/1.1722960· OSTI ID:4303822

Deeley, C W; Sauer, J A; Woodward, A E

Samples of a ''high-density'' polyethylene (p = 0.984 g/ cc) irradiated in a nuclear reactor to thermal neutron doses as high as 2.9 x 10/sup 18/ nvt aad of''low-density'' polyethylene (p = 0.915 g/cc) subjected to gamma-ray bombardment from a Co/sup 60/ source up to a dosage of 1 x 10/sup 9/ rep have been investigated by dynamic mechanical methods from 80 to 450/DEK at audio- frequencies. Degrees of cross-linking were estimated from the observed changes in resonance frequency at temperatures where the specimens were ''rubber-llke.'' Densities and x-ray crystallinities at 25 deg C were also measured. For the pile- irradiated ''high-density'' polyethylene the gamma peak found around 185 deg K shows a marked increase in height and area at dosages above 10 nvt. The a peak at about 390 deg K decreases markedly upon receiving a thermal neutron dose of 0.8 x 10 nvt. For her changes in this absorption with higher dosages are obscured by the appearance of a BETA peak around 330 deg K which is almost absent in the unirradiated material; the appearance of the BETA region is attributed to the creation of branch points and cross-link points in the essentially linear polymer by the irradiation. The irradiated ''low-density'' specimens exhibit three damping peaks. Over the dosage range studied the gamma peak (185 deg K) increases in height and area, the BETA peak (270 deg K) shifts to higher temperatures, and the a peak (360 deg K) shifts to lower temperaturss with increasing dose. The cross-linking degree is not proportional to dose and to the highest dosages studied, there is very little, if any, reduction in x-ray crystallinity. (auth)

• Research Organization: Pennsylvania State Univ., University Park
• Sponsoring Organization: USDOE
• NSA Number: NSA-12-016992
• OSTI ID: 4303822
• Journal Information: Journal of Applied Physics (U.S.), Journal Name: Journal of Applied Physics (U.S.) Vol. Vol: 29; ISSN JAPIA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

BONDING
CHEMISTRY
COBALT 60
DENSITY
FREQUENCY
GAMMA RADIATION
IRRADIATION
LATTICES
MECHANICAL PROPERTIES
NEUTRON BEAMS
POLYETHYLENES
RADIATION DOSES
TEMPERATURE
X RADIATION