Characterization Of Carbon Foam Research Articles

Preparation and characterization of carbon foams derived from cyanate esters and cyanate/epoxy copolymers

The aim of this study was to obtain carbon foams (CFs) of various pore structure and high mechanical strength using a simple and efficient method to fabricate carbonization products from bisphenol A-based cyanate ester and their copolymer with low-molecular diglycidyl ether of bisphenol A. The physical–chemical characteristics, surface structure and thermal stability of cured cyanate and cyanate/epoxy matrices as well as the CFs were investigated by vibrational Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The relation between the physical–chemical properties of carbon materials obtained and the chemical composition of polymer precursor, and the conditions of their production were determined. The results showed that CF with the pore size of 50–200 μm could be directly prepared by carbonization of the polymer matrix at ambient pressure.

Preparation and characterization of carbon foams from cyanate ester mixtures

Carbon foams were prepared by direct pyrolysis of cyanate ester (CE) resins from the mixtures of phenol novolac cyanate ester (PNCE) and bisphenol A cyanate ester (BACE) at ambient pressure. Pyrolysis behaviors of the CE resins were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, influences of PNCE/BACE mass ratio on the characteristics of the resultant carbon foams were studied. Results show that the CE resin possesses better thermal stability with increasing PNCE/BACE mass ratio, whereas its self-foaming performance becomes worse during pyrolysis. The addition of PNCE to BACE leads to an increase in the bulk density of the resultant carbon foam but a decrease in both its porosity and open cell. Moreover, the compressive strength of the carbon foam increases with an increase in the PNCE/BACE. When the PNCE/BACE mass ratio varies from 0 to 0.75, the compressive strength of the carbon foam prepared increases from 3.25 to 9.6MPa.

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

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 21.27MPa when the additive amount of CMA is 7wt%.