Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
40, Number 4, April, pp. 181-186
Polymer-Additive Extraction via Pressurized Fluids and Organic
Solvents of Variously Cross-Linked Poly(methylmethacrylates)
N. Nazem and L.T. Taylor
Department of Chemistry, Virginia Tech, Blacksburg, VA 24061-0212
Variously cross-linked poly(methylmethacrylates) (PMMAs) are
synthesized with three additives incorporated at theoretically 1000 µg
of the additive per gram of prepared polymer. The additives are Irganox 1010,
Irganox 1076, and Irgafos 168. The in-house synthesized polyacrylates
are then subjected to supercritical fluid extraction (SFE) to determine if additive
recovery is a function of percent cross-linking. Although considerable work
in this regard has been performed with non-cross-linked polyolefins, the literature
is lacking regarding polyacrylates. Some additive degradation apparently occurs
during the synthesis, as judged by the increased complexity of the extract high-performance
liquid chromatographic trace and the low percent recoveries observed especially
for the Irganoxes. For low polymer cross-linking (1%), it appears that both
PMMA synthetic reproducibility and readily observed polymer swelling during
SFE are serious issues that adversely affect additive percent recovery and precision
of results. Higher percent cross-linking yields more consistent analytical data
than low percent cross-linking, even though the amount of additive extracted
in all PMMA samples (regardless of cross-linking percentage) is essentially
the same whether the extraction is via SFE or liquidsolid extraction with
methylene chloride. Results for comparably cross-linked poly(ethylmethacrylate)
and poly(butylmethacrylate) are similar to PMMA.
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