The effect of radiation-induced cross-linking on the relaxation of taut tie molecules during annealing of drawn LDPE

Journal Article · Fri Feb 05 00:00:00 EST 1993 · Journal of Applied Polymer Science; (United States)

OSTI ID:6783805

Yan, Rong Jiang; Luo, Yunxia; Jiang, Bingzheng ^[1]

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1. Changchun Inst. of Applied Chemistry (China)

Shrinkage, retractive stress, and infrared dichroism of the drawn low-density polyethylene (LDPE) as-drawn and irradiated by [sup 60]Co-ray have been measured under different annealing conditions. The shrinkage and the disorientation of the irradiated sample was undergone more rapidly than that of unirradiated one as the temperature was continuously increased, surpassing a certain value, and a higher degree of shrinkage and disorientation was achieved finally for the irradiated sample when the samples were annealed with free ends. For the samples heated isothermally with fixed ends, the retractive stress went through a maximum and then attenuated to a limited value, and the degree of such a stress attenuation for the unirradiated sample was much more than that for the irradiated sample. These results show that the taut tie molecules (TTMs) in drawn PE can relax by the pulling of chain segments out of crystal blocks that they anchored in at elevated temperatures higher than the [alpha] transition and also by the displacing of microfibrils if the samples were annealed with free ends. The cross-links produced by irradiation prohibit the former process. It was further observed that the dependence of the average extinction coefficient of the band at 2,016 cm[sup [minus]1] on that of the band at 1,894 cm[sup [minus]1] is related to irradiation and annealing conditions, which has also been explained by the relaxation of TTMs and the function of irradiation-induced cross-linking on the relaxation.

• OSTI ID: 6783805
• Journal Information: Journal of Applied Polymer Science; (United States), Vol. 47:5; ISSN 0021-8995
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
POLYETHYLENES
RADIATION EFFECTS
ANNEALING
COBALT 60
CROSS-LINKING
MOLECULES
STRESS RELAXATION
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL REACTIONS
COBALT ISOTOPES
HEAT TREATMENTS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERIZATION
POLYMERS
POLYOLEFINS
RADIOISOTOPES
RELAXATION
YEARS LIVING RADIOISOT
400600* - Radiation Chemistry