Molecular weight distributions of irradiated siloxane-based elastomers: A complementary study by statistical modeling and multiple quantum nuclear magnetic resonance

Journal Article · Sun May 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3587169· OSTI ID:21560238

Dinh, L N; Mayer, B P; Maiti, A; Chinn, S C; Maxwell, R S ^[1]

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1. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

The statistical methodology of population balance (PB) has been applied in order to predict the effects of cross-linking and chain-scissioning induced by ionizing radiation on the distribution of molecular weight between cross-links (MWBC) of a siloxane-based elastomer. Effective molecular weight distributions were extracted from the quantification of residual dipolar couplings via multiple quantum nuclear magnetic resonance (MQ-NMR) measurements and are taken to reflect actual MWBC distributions. The PB methodology is then applied to the unirradiated MWBC distribution and considers both chain-scissioning and the possibility of the formation of three types of cross-links: random recombination of scissioned-chain ends (end-linking), random covalent bonds of free radicals on scissioned-chain ends (Y-cross-linking), and the formation of random cross-links from free radicals on side groups (H-cross-linking). The qualitative agreement between the statistical modeling approach and the NMR data confirms that it is possible to predict trends for the evolution of the distribution of MWBC of polymers under irradiation. The approach described herein can also discern heterogeneities in radiation effects in different structural motifs in the polymer network.

• OSTI ID: 21560238
• Journal Information: Journal of Applied Physics, Vol. 109, Issue 9; Other Information: DOI: 10.1063/1.3587169; (c) 2011 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CHEMICAL BONDS
CROSS-LINKING
DISTRIBUTION
ELASTOMERS
EVOLUTION
IONIZING RADIATIONS
IRRADIATION
MOLECULAR WEIGHT
NUCLEAR MAGNETIC RESONANCE
RANDOMNESS
RECOMBINATION
SILOXANES
SIMULATION
CHEMICAL REACTIONS
MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
POLYMERIZATION
POLYMERS
RADIATIONS
RESONANCE