Influence of Evaporation Drying on the Porous Properties of Carbon/Carbon Composite Xerogels.

Kriangsak Kraiwattanawong,Noriaki Sano,Hajime Tamon

doi:10.3390/polym13162631

Kriangsak Kraiwattanawong, Noriaki Sano + Show 1 more

Open Access

https://doi.org/10.3390/polym13162631

Copy DOI

Abstract

Carbon/carbon (C/C) composite xerogels dried by evaporation were prepared in this study to observe the change of their porous properties and their morphology by nitrogen sorption apparatus and a scanning electron microscope. Resorcinol and formaldehyde (RF) sols as a matrix phase and cotton fibers (CF) as a dispersed phase were mixed and gelated to be CF/RF composite hydrogels. The composite hydrogels were exchanged by t-butanol (TBA), dried by evaporation at 50 °C, and carbonized at 1000 °C to become the C/C composite xerogels. The results show that the CF addition does not decrease the mesoporous properties of the C/C composite xerogels. Moreover, the CF addition can alleviate the pore shrinkage, and it can maintain the mesopore structure. The mesopore size and the micropore size of C/C composites are insignificantly changed because the CF addition and the solvent exchange using TBA may suppress the pore shrinkage despite the gas-liquid interface existing during the evaporation drying.

Highlights

Organic aerogels and carbon aerogels have a high BET surface area (SBET) and large mesopore volumes (Vmes)
The microstructures of carbon cryogels, the carbon xerogels, and the C/C composite xerogels are observed, and the scanning electron microscope (SEM) images are presented in Figures 1 and 2
The carbon structure of carbon cryogels, carbon xerogels, and the C/C composite xerogels consist of nanoparticles forming the mesopores

Summary

Introduction

Organic aerogels and carbon aerogels have a high BET surface area (SBET) and large mesopore volumes (Vmes) They can be prepared by the sol-gel polymerization of resorcinol with formaldehyde (RF), followed by supercritical drying with carbon dioxide and carbonization under inert gas [1,2,3,4,5,6,7,8]. Their pore structure can be controlled by changing the amounts of reactants, catalysts, and water [6]. Freeze drying is an inexpensive method, but it needs an expensive high vacuum pump and deep chiller

Objectives

Results

Conclusion