Delayed-onset Polymer Cross-linking using Functional Nitroxyls
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Authors
Hyslop, David
Date
2012-06-11
Type
thesis
Language
eng
Keyword
tempo , crosslink , polyethylene , cross-link , cure , delayed action , dicumyl peroxide , radical , nitroxyl , scorch
Alternative Title
Abstract
New polymer cure chemistry is described, wherein the onset of free radical cross-linking is delayed without compromising cure yields. The addition of an acrylate-functionalized nitroxyl, 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl (AOTEMPO), to a peroxide-cure formulation quenches free radical activity during the initial stages of the cross-linking process, trapping alkyl radicals as alkoxyamines that bear acrylate functionality. Polymer cross-linking by macro-radical combination is suppressed until all nitroxyl is consumed, at which point radical oligomerization of polymer-bound acrylate groups generates the desired covalent network. As a result, cross-link density losses incurred during radical trapping are recovered during the oligomerization phase of the process. The effectiveness of this approach is demonstrated for a range of polymers, peroxide initiators, reaction temperatures and reagent loadings. Furthermore, AOTEMPO formulations are compared directly to other delayed-onset additives that are used in commercial practice.
Description
Thesis (Master, Chemical Engineering) -- Queen's University, 2012-06-11 10:09:20.848
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