The fire performance of phenolic foam is exceptional. It exhibits very low flame spread with negligible smoke emission and a very low level of toxic gas emission. Thus it is recognized as an exceptional FST [Fire, Smoke, low Toxicity material] for thermal insulation. The precursor to phenolic foam is a phenol formaldehyde resin known as resole and prepared by reaction of phenol with formaldehyde under basic conditions. A renewable aromatic material available in extremely large quantities from the paper pulping operations of softwood or hardwoods is lignin. A favorable oxidative degradation process of lignin yields low molecular weight phenolic materials and facilitates co-reaction during the reaction of phenol with formaldehyde into a lignin modified phenolic resole resin. The resulting lignin modified phenolic resole resin containing 20% oxidative degraded lignin was transformed into phenolic foam whose foam characteristics were similar to conventional phenolic foam in thermal conductivity and limiting oxygen index but exhibited better compressive strength that the conventional phenolic foam.
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