ɛ-caprolactone and pentaerythritol derived oligomer for rigid polyurethane foams preparation

Copolymerization of pentaerythritol with five equivalents of ɛ-caprolactone leads to tetra-functional branched oligomer terminated with hydroxyl groups. The product was characterized by elemental analysis, IR and NMR spectroscopy, gel permeation chromatography and physical methods to determine viscosity, density and surface tension. The oligomer was then used to obtain rigid polyurethane foam. The foam was characterized by physicochemical methods to determine: apparent density, water uptake, polymerization shrinkage, heat conductance coefficient, thermal stability, compression strength and biodegradation. The foam obtained from this oligomer have the properties similar to classic rigid polyurethane foams but enhanced thermal resistance. It can stand long time heating at 175°C, while its compression strength increases upon thermal exposure. The foam and oligomer are biodegradable; the oligomer is fully decomposed within 28 days in soil, while the foam obtained from it is in the same conditions degradable up to 28% of initial mass.