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Introduction
Electron irradiation of deaerated monomeric or oligomeric acrylates leads to polymerization
and crosslinking. The concentration of acrylic double bonds decreases and a stable
crosslinked network is formed. But in the dose range between 20 and 50 kGy, which is
usually needed to cure the acrylate formulation, a low amount of unreacted monomer, remains
detectable. In some cases post irradiation polymerization and crosslinking are observed to
proceed at rising temperature. Moreover, the cured acrylates are not completely unsoluble. A
few percent of solubles are present at high curing doses.
For practical use a variety of. test methods has been developed to examine the quality of a
cured coating e.g., rub and scratch resistance,pendulum hardness, determiation of gloss,
shrinkage, flexibility, odour or weatherability. However, the "degree of cure" is not a well
defined quantity.
In this study we report on the characterization of the degree of cure of ER cured model
formulations as function of the applied dose. Different analytical methods such as GC, HPLC,
FTIR; DSC, GC-MS and IMS were used to gain information about the content of double
bonds, extractables; gel fraction; radiolysis products and post cure effects. Summarizing the
results obtained from these different analytical techniques, the degree of cure of an acrylate
coating can be characterized in a more fundamental way.
