One-Pack Epoxy Foaming with CO<sub>2</sub> as Latent
Blowing Agent
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Abstract
In this work, we have successfully
developed a novel approach to
epoxy foaming using CO<sub>2</sub> as the latent blowing agent. The
active amine groups of a commercially available curing agent for epoxy
resin are blocked by CO<sub>2</sub> to obtain ammonium carbamate.
The prepared ammonium carbamate can be decomposed by heating. Above
100 °C, CO<sub>2</sub> is released from the amine groups and
acts as the blowing agent, while the amine compound is used as the
curing agent and cures the epoxy resin. The ammonium carbamate combines
the functionalities of latent blowing agent and curing agent. The
one-pack epoxy foaming formulation has good storage stability under
ambient conditions. The thermoset epoxy foams prepared from the one-pack
formulation have low density, good mechanical properties, and thermal
stability, competitive with the epoxy foams prepared by other methods.
This novel approach is simple, environmentally benign, and cost-effective,
which represents a promising direction in the development of epoxy
foaming technologies