Preparation of a foam using tannin-glyoxal-furfuryl alcohol copolycondensation resin

LIU Bowen;LI Xuehui;ZHOU Yunxia;ZHOU Zhaoling;ZHOU Xiaojian;ZHANG Jun;DU Guanben;Key Laboratory of Wood Adhesives and Glued Products of Yunnan Province,Southwest Forestry University;

tannin resin;;glyoxal;;furfuryl alcohol;;biomass foam;;compressive strength

In order to develop a non-toxic and degradable foam using biomass materials to replace non-renewable foam materials, in this study, glyoxal was used to replace formaldehyde, cross-linked with tannin and furfuryl alcohol under acidic conditions, and Tween 80 was used as an emulsifier. A biomass tannin-furfuryl alcohol-glyoxal thermosetting(TFG) foam with similar properties to phenolic resin foam was prepared and the preparation process of TFG foam was explained. Through its density, compressive strength, water absorption, thermal conductivity and thermal conductivity, the reanalysis test characterized its physical properties, and a scanning electron microscope was used to observe the internal pore structure of the foam. The experimental results showed that the glyoxal can undergo an aldol condensation reaction with furfuryl alcohol to form a group —C—O—C—, creating a stable chemical structure, and the internal morphology test of the foam showed that the use of glyoxal as the cross-linker, the foam material of the joint agent had a uniform distribution of cells and more dense cells without cracks and collapses. The test results of foam apparent density showed that the density of TFG foam met the requirements of lightweight foam. The thermogravimetric analysis and thermal conductivity tests showed that, because the number of benzene rings connected to —OH in the tannin structure was much greater than that of phenol, the carbon content was high, and it contained more heteroepoxy atoms, so the heat resistance of tannin-based foam was better than that of phenolic foam at 300 ℃. The thermal conductivity test showed that the TFG foam prepared by replacing formaldehyde with glyoxal as a cross-linking agent had good thermal insulation performance. In addition, the Fourier infrared spectroscopy analysis showed that the glyoxal can replace formaldehyde to cross-link with tannin and furfuryl alcohol to form a macromolecular structure, so that TFG foam had a complex chemical network. After the foam was cured, its structure would help improve mechanical properties and reduce the degree of pulverization. The mechanical performance test showed that, because glyoxal can cross-link with tannin and furfuryl alcohol to produce a strong network structure, there were large amounts of triangular skeleton structures between the cells, so it had good mechanical properties, and the mechanical properties were better than phenolic resin foam. In summary, the performance of TFG foam is better than that of phenolic resin foam, with an advantage of “non-toxic”, which is conducive to the industrial production and practical utilization.