Observation by 13C n.m.r. of H-crosslinks and methyl end groups due to main-chain scission in ethylene-propylene copolymers after γ-irradiation

O'Donnell J.H. and Whittaker A.K. (1992) Observation by 13C n.m.r. of H-crosslinks and methyl end groups due to main-chain scission in ethylene-propylene copolymers after γ-irradiation. Polymer, 33 1: 62-67. doi:10.1016/0032-3861(92)90560-J


Author O'Donnell J.H.
Whittaker A.K.
Title Observation by 13C n.m.r. of H-crosslinks and methyl end groups due to main-chain scission in ethylene-propylene copolymers after γ-irradiation
Journal name Polymer   Check publisher's open access policy
ISSN 0032-3861
Publication date 1992-01-01
Sub-type Article (original research)
DOI 10.1016/0032-3861(92)90560-J
Volume 33
Issue 1
Start page 62
End page 67
Total pages 6
Subject 1605 Policy and Administration
2507 Polymers and Plastics
Abstract High resolution 13C n.m.r. spectra were obtained from two ethylene-propylene copolymers containing 23% (EP23) and 36% (EP36) propylene swollen with CDCl3 after γ-irradiation, although the line widths increased and the intensities of the original resonances decreased with increasing radiation dose. A resonance at 42 ppm after low doses (0.02-0.14 MGy) was attributed to methine carbons in H-crosslinks. New resonances at 11.3, 14.1, 14.5, 22.7 and 23.1 ppm were assigned to methyl and methylene groups on various chain-end structures arising from main chain scission, and yields (G values) were derived for doses up to 2 MGy. G (scission) values of 0.16 and 0.37 for EP23 and EP36, respectively, were in good agreement with values derived previously from soluble fraction measurements and from solid-state n.m.r. spectra after much higher radiation doses. The proportions of different chain-end structures suggested that scission was favoured by a factor of 1.6 at C-C bonds adjacent to the methyl substituents compared with other main-chain C-C bonds.
Keyword crosslinks
ethylene-propylene
n.m.r.
radiation
scission
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Scopus Import - Archived
 
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