Abstract
During the down-stream processing of an undiluted epoxy resin, water contamination, e.g. due to the failure of a tube of a heat exchanger, can introduce the risk of an unwanted hydrolysis reaction, followed by a cross- linking reaction. The latter, despite not being inherently dangerous, can lead to a dramatic increase of viscosity and the subsequent loss of agitation, bringing the resin in pseudo-adiabatic conditions and limiting the possibilities of intervention. Depending on the type of resin, the heat released by these reactions and the opening of epoxy rings can remain confined in the core of the mass and accumulate, triggering product decomposition: this may represent a significant hazard, potentially leading to high temperature carbonisation, gas release, overpressure with potential for vessel burst and/or release of toxic substances.
Thermal Safety investigations were carried out to characterise the hydrolysis, crosslinking and decomposition reactions after water contamination, assessing different types of remediation actions that the plant may take to solve the situation. In particular, vacuum distillation of water has been identified as the most straightforward method to remove instability and normalise the situation.
However, the reactive behaviour of the mass can be significantly different depending on the conditions in which the distillation is carried out, and it is found that early cross-linking may happen during the distillation if no solvent is added, before the water is actually removed.
In the undesirable situation where contaminated resin waste is generated on site, product characterisation and aging testing can determine how to safely manage it during storage and transportation to a third party for destruction.
