Characterization and Preparation of Furanic-Glyoxal Foams

Abstract

Synthetic foams have become an essential industrial product for a great variety of applications. Furfuryl alcohol, as a biomass chemical, was reacted with glyoxal at room temperature to prepare furanic-glyoxal rigid foams, and p-toluenesulfonic acid was used as a catalyst to initiate the reaction. Foams with different molar ratios (furfuryl alcohol/glyoxal) were prepared in this work, and uniform cells foams have been obtained. Their compression resistance, 24-h water absorption, density, and other basic properties were tested. Scanning electron microscopy (SEM) was used to observe the cellular morphology of the foams prepared, thermogravimetric analysis (TGA) helped to understand their thermal and combustion properties, and FTIR and Matrix Assisted Laser Desorption Ionisation Time of Flight (MALDI ToF) mass spectroscopy to explain the structure of the resulting foams to clarify the reactions occurring during foaming. The results show that the compression resistance of furanic-glyoxal foams declined as the furfuryl alcohol/glyoxal ratio decreases also. SEM observations revealed that foams with open-cell were obtained when furfuryl alcohol was added in greater amounts, and more closed cell structures were formed as the proportion of glyoxal increased. TGA results showed that the initial ignition temperature of furanic-glyoxal foams is ~200 °C higher than that of wood, and the smaller comprehensive combustion index S (about 0.15 × 10−7 (%2 K−3 min−2)) indicates that the foam burns slowly and has poor flammability, that is, it is not easy to burn.

Ambient Temperature Self-Blowing Tannin-Humins Biofoams

“…The initial exploratory series was composed of the following formulations: FA + glyoxal control, thus an only furanic foam without tannin [ 32 ] FA + glyoxal + humins: 2.5 g humins + 9 g FA + 11.4 g glyoxal + 4 g olive powder + 3.6 g p-TSA+ 1.5 DE (foaming agent); thus, a mixed furfuryl alcohol-humins. An only furanic foam.…”

Recent Developments in Biobased Foams and Foam Composites for Construction Applications

“…Numerous studies investigated the replacement of the phenolic fraction with tannins for the production of BPF foams [124,125,140,[193][194][195][196][197][198][199][200][201][202][203] and adhesives [196,[204][205][206][207][208][209][210][211]. However, limited research has focused on replacing the formaldehyde fraction with compounds like glyoxal [34,212,213], hydroxymethylfurfural (HMF) or furfural [8,26].…”

Effect of the pH value of tannin extracts on properties of classic tannin foams

“…2,4 Compared to those foams derived from formaldehyde, glyoxal-based ones already reached more homogeneous porous structures and similar (sometimes higher) performances. 10,13…”

“…Currently, polyurethane, polystyrene, polyvinyl chloride, and synthetic phenolic are the main rigid foams produced from oil derivatives and have been applied for agriculture, transports, packaging, and construction sectors. 4,12,13 These oil-based foams could be replaced by tannin-based ones. [14][15][16][17][18] In addition to adjustable density and highly low thermal conductivity, rigid tannin-based foams have a high flame spread resistance and do not emit harmful gases.…”

“…2,4 Compared to those foams derived from formaldehyde, glyoxal-based ones already reached more homogeneous porous structures and similar (sometimes higher) performances. 10,13 The pH values of both the liquid polymer phase and tannin extract may significantly affect the final performance and potential uses of rigid tannin-furanic foams. 23 Most foams have been produced in strongly acidic conditions, 2,11,14,[26][27] although some studies dealt with tannin foams risen in alkaline conditions.…”