Phenolic foam prepared by lignin from a steam-explosion derived biorefinery of corn stalk

Abstract:

To increase the integral economic effectiveness, biorefineries of lignocellulosic materials should not only apply carbohydrates hydrolyzed from cellulose and hemicellulose but also used lignin We used steam-exploded corn stalk as raw materials and optimized the temperature and alkali concentration in the lignin extraction process to obtain lignin liquor with higher yield and purity. Then the concentrated lignin liquor was used directly to substitute phenol for phenolic foam preparation and the performances of phenolic foam were characterized by microscopic structure analysis, FTIR, compression strength and thermal conductivity detection. The results indicate that, when steam-exploded corn stalk was extracted at 120 ℃ for 2 h by 1% NaOH with a solid to liquid ratio of 1:10, the extraction yield of lignin was 79.67%. The phenolic foam prepared by the concentrated lignin liquor showed higher apparent density and the compression strength with the increasing substitution rate of lignin liquor. However, there were not significant differences of thermal conductivity and flame retardant properties by the addition of lignin, which meant that the phenolic foam substituted by lignin liquor was approved for commercial application. This study, which uses alkali-extracted lignin liquor directly for phenolic foam preparation, provides a relatively simple way for utilization of lignin and finally increases the overall commercial operability of a lignocellulosic biorefinery derived by steam explosion.