Marie-Christine Lagel

Alkaline Tannin Rigid Foams

Condensed fl avonoid tannin foams were obtained under alkaline conditions. This entailed the elimination of furfuryl alcohol from these formulations, as under alkaline conditions, foam preparation could not rely on the heat generated by the self-condensation of furfuryl alcohol, which occurs only under strongly acidic conditions. The approach used to formulate the alkaline foam was: (i) the total elimination of furfuryl alcohol from the formulation, (ii) coupled with the use of an aldehyde hardener different from formaldehyde (for environmental reasons) and (iii) the application of moderate heat to allow foaming. These were not tannin/ furanic foams as their acid-curing counterparts, but tannin only foams. The open cell foams were evaluated for bulk density, compressive strength, thermal conductivity and fi re resistance. Their characteristics were similar to the acid-curing tannin/furanic foams.

Matrix-Assisted Laser Desorption-Ionization Time of Flight (MALDI-TOF) Mass Spectrometry of Phenol-Formaldehyde-Chestnut Tannin Resins

Natural hydrolysable chestnut tannin extracts used to partially substitute phenol in Phenol-Formaldehyde (PF) resins for phenolic rigid foams were analysed by matrix-assisted desorption ionization time of flight (MALDI-TOF) mass spectrometry. PF only, chestnut only and PF-chestnut copolymerised oligomer types and distribution were determined. MALDI-TOF analyses of a PF control resin (with the same molar ratio) and of chestnut tannin extracts were performed in order to identify the peaks of molecular weights corresponding to copolymers of chestnut tannins with phenol and formaldehyde.

Development and Characterisation of Phenolic Foams with Phenol-Formaldehyde-Chestnut Tannins Resin

With the depletion of fossil resources, tannin extracts can be a natural alternative to some synthetic products. Hydrolysable chestnut tannin extracts have been used to partially replace phenol in PF resins for phenolic rigid foams. Phenol-formaldehyde-chestnut tannin (PFT) phenolic foams were initially made from copolymerized PFT resins of different molar ratio. The PFT foams so prepared were tested for thermal conductivity, these being slightly worse than that of pure PF foams; and for mechanical and water absorption, these two properties being better than those of pure PF foams. Indeed, PF resins represent an important part of synthetic resins. They are used in different fields of application such as in phenolic foams or for the preparation of particleboard. So it is important to work on the possibility of going green with these resins.

Characterization of Merbau Wood Extract Used as an Adhesive in Glued Laminated Lumber

Abstract Polyphenolic chemical compounds were extracted from merbau (Intsia spp.) wood with an aqueous medium at a 1:4 ratio (wt/wt) heated to 80°C for 3 hours. The extracted compounds were characterized by matrix assisted laser desorption ionization time of flight spectrometry and included oligomers with up to six repeating flavonoid units, with resorcinol being the dominant compound paired with a minor amount of catechin units. The extract had a Stiasny number of 92.4 percent. The extract was combined with formaldehyde to produce a resin that was used to manufacture five-layer glued laminated lumber using four wood species, namely, pangsor (Ficus callosa), mindi (Melia azedarach), pine (Pinus merkusii), and mangium (Acacia mangium). The modulus of rupture and shear strength of mangium glued laminated lumber met the requirements of the Japanese standard (“Japanese Agricultural Standard for Structural Glued Laminated Timber,” 2003), and all products had a low formaldehyde emission.