Preparation and properties of carbon foam by direct pyrolysis of ally novolak-modified bismaleimide resin

•Ally novolak-modified bismaleimide resin is a suitable carbon foam precursor.•Carbon foam can be prepared by direct pyrolysis of the resin at ambient pressure.•The carbon foam has a uniform and well-developed pore structure.•The carbon foam has a high specific strength as well as a low thermal conductivity.

Carbon foam was prepared by direct pyrolysis of ally novolak (AN)-modified bismaleimide (BMI) resin at ambient pressure. Pyrolysis behavior of the AN-modified BMI (AMB) resins was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, influences of AN/BMI mass ratio on the structures and properties of the resulting carbon foams were studied. Results show that the AMB resin possesses self-foaming characteristics at high temperatures. The carbon foams have well-developed pore structures with relatively uniform pore sizes; their bulk density, thermal conductivity and compressive strength increase with a decrease in AN/BMI mass ratio. When the AN/BMI mass ratio is 1:1.1, the bulk density, thermal conductivity and compressive strength of the carbon foam arrive at 0.43 g/cm3, 1.02 W/mK and 6.4 MPa, respectively.