Preparation of polybenzoxazine foam and its transformation to carbon foam

An organic foam derived from a new type of phenolic resin, namely polybenzoxazine, was successfully prepared with a noncomplex and economical foaming method by using azodicarbonamide (AZD) as a foaming agent. The influence of foam density on the physical and mechanical properties of the foams was studied. All resulting polybenzoxazine foams and carbon foams exhibit a tailorable uniform microstructure. Polybenzoxazine foams showed a density in the range of 273–407 kg/m³, and a compressive strength and a compressive modulus in the range of 5.2–12.4 MPa and 268–681 MPa, respectively. The foam density not only affects the physical and mechanical properties, but also affects the deformation response of the foam. In addition, the polybenzoxazine foam was further transformed into carbon foam by carbonization at 800 °C under an inert atmosphere, and its properties were examined.