Preparation and characterization of carbon foams with high mechanical strength using modified coal tar pitches

• The chemical composition and softening point of pitches could be adjusted by cinnamaldehyde (CMA) and boric acid.
• The chemical composition and softening point of pitches have a significantly effect on the foam structure of obtained carbon foams.
• It is an effective way to improve the mechanical strength of carbon foam using pitches obtained after modification with CMA and boric acid.

Carbon foams with high mechanical strength were prepared using coal tar pitches modified with cinnamaldehyde (CMA) and boric acid, via pretreatment, foaming and carbonization process. The properties of modified pitches, pretreatment pitches and resultant carbon foams were studied by Fourier transform infrared spectroscopy (FTIR), optical microscope, thermogravimetry analyzer, X-ray diffractometer (XRD), scanning electron microscope (SEM) and universal testing machine, respectively. Results show that the chemical composition and softening points of pitches are adjusted by modification with different amount of CMA, as well as the morphology and properties of pretreatment pitches. The relation between the properties of modified coal tar pitches and the structure of resultant carbon foams is also investigated. Investigation indicates that the composition and softening point of pitches have a significant impact on the morphology and properties of resultant carbon foams. Moreover, the mechanical strength of carbon foam is also improved via modification of pitches and the highest mechanical strength reaches to 21.27 MPa when the additive amount of CMA is 7 wt%.