Development of Dispersion and Length-evaluation Methods of Vapor-grown Carbon Fiber

Abstract

We have investigated the effect of dissolving organic polymers on the dispersion of VGCF (vapor-grown carbon fiber) TM in various organic solvents through optical microscope observation. VGCFTM as received had aggregated structure with particle shapes having a broad diameter distribution. We have used tetrahydrofran (THF), dimethylformamid (DMF), benzene (BZ), and dichloromethane (DCM) as organic solvents, and polycarbonate (PC), polystyrene (PS), and polymethylmethacrylate (PMMA) as organic polymers. After stirring VGCFTM in each organic solvent, most VGCFTM was remained as the aggregated particle structure which had similar structure as received. However, it was found that VGCFTM aggregated particles disappeared and were dispersed individually by dissolving organic polymers in the solvents after stirring for 30min. We have discussed the correlation between the polymer structures and the dispersion of VGCFTM. Furthermore, several drops of THF/PC solution containing individually dispersed VGCFTM, which was the best composition in the series of experiments which used four solvents and three polymers, was put on a cover glass, and THF was removed by spin coating, resulting in PC/VGCFTM thin film on the cover glass. PC was decomposed by heat treatment, and only dispersed VGCFTM whose both ends were clearly observed on the cover glass were finally obtained. Through measuring the length of VGCFTM by SEM with the help of an image analysis soft ware, the exact averaged length was determined.