Thermogravimetric analysis of anningre tannin resin

Abstract

Three formulations of aningre tannin resins containing in order the paraformaldehyde powder, hexamethylenetetramine and aqueous glyoxal as hardeners were developed. Their thermogravimetric analysis have shown that they begin to decompose respectively from 135°C, 145°C and 140°C. About 24%, 40% and 39 % solid residues of their initial masses exist at the end of the analysis. Thermomechanical analysis has shown that the formulation containing paraformaldehyde powder as hardener has the best rigidity and the worst contains the hexamethylenetetramine. All formulations have different thermal degradation, differences were more significant between 400 and 900°C.The decomposition of hardeners become more significant from 400°C.

Development of Quebracho (Schinopsis balansae) Tannin-Based Thermoset Resins

“…The first one (25-130 • C) characterizes mainly loss of water absorbed and traces of volatile compounds such as CO and CO 2 . The second region (135-600 • C) is typical of the degradation of later chains of the tannin and decomposition of hardeners, with the cleavage of C-C bonds forming CH 4 , CO, or CO 2 [34,35]. In particular, two main events occur for a tannin degradation: the first, at around 260 • C, corresponds to decarboxylation, and the other one at, around 600 • C, corresponds to oxidation of high-carbon residues [36].…”

“…In particular, two main events occur for a tannin degradation: the first, at around 260 °C, corresponds to decarboxylation, and the other one at, around 600 °C, corresponds to oxidation of high-carbon residues [36]. The last region between 600 and 800 °C is characterized by the decomposition of natural structures of tannins, in particular involving the disruption of the polyphenolic structure (rings A and B) [35]. Overall, it can be observed that the thermal degradation of the quebracho cured polymers is similar for all hardeners and presents a constant degradation pattern involving an acceleration between 250 and 300 °C for all polymers.…”

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“…The two previous solutions were mixed in a 50:50 ratio and about 0.5 to 1 µl of this mixture was placed on the sample holder. The sample holder was then introduced in the spectrometer (Aixima Performance, Shimadzu UK, Manchester, UK) after evaporation of the solvent for a few minutes in the open air [15].…”

“…Several tannins have been characterized in order to see their effectiveness in the development of wood adhesives. [4,[13][14][15][16][17]].…”

“…42% of the national area, with 300 available species, 80 of which are exploited by forestry companies, producing more than 1.2 million tons of residues each year [18]. Studies to enhance the tannin production of certain species of Cameroonian forests have been carried out for use as an adhesive in board manufacture [7,15] and in pharmaceuticals [19][20][21]. Despite the potentially abundant supply in the tropical forests of the Gulf of Guinea, studies to detect and develop tannin production remains a vague area that deserves special attention.…”