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Tannin-Based Copolymer Resins: Synthesis and Characterization by Solid State 13C NMR and FT-IR Spectroscopy
Full text linkIn recent years, the interest for bio-sources is rising exponentially and tannins extracts are one of the most interesting, easily-available, phenolic building blocks. The condensed tannins or proanthocyanidins are already known for their polymerization chemistry, which is the basis for several natural-based materials (e.g., adhesives, foams). In the present work we aim to observe the behavior of the extract of Acacia Mimosa (Acacia mearnsii) when reacted with several possible co-monomers at different relative amount, pH and temperature conditions. The more insoluble copolymers obtained with formaldehyde, hexamine, glyoxal, maleic anhydride, furfural and furfuryl alcohol were analyzed through solid state 13C NMR (Nuclear magnetic resonance) and FT-IR (Fourier Transform-Infrared) spectroscopy. The 13C NMR afforded the opportunity to detect: (i) aromatic substitutions and consequent poly-condensations for the majority of the hardeners studied; (ii) acylation for the maleic anhydride and also some; (iii) Diels–Alder arrangements for the furanic co-monomers; the FT-IR spectroscopy suggested that the formaldehyde and hexamine copolymers present a higher cross-linking degree
Middle infrared (ATR FT-MIR) characterization of industrial tannin extracts
No full textIn the present paper a detailed investigation of the molecular vibrations of eight industrial tannin powder extracts is presented. The ATR FT-MIR spectra observed in the spectral window between 1800 and 600cm-1 allow specific band profiles to be identified which are typical for the various hydroxyl-aromatic molecules that constitute the tannin extracts. Hence, it was possible to rapidly discriminate the two main families of tannin. The "hydrolysable" tannins show intense absorptions in the region of the CO at around 1700cm-1 and also two major "single" bands at around 1315 and 1180 to be assigned to aromatic C-O. Conversely, the flavonoids of the "condensed" tannins present an overall structured profile especially in the region between 1400 and 1100cm-1. Spectra of tannin extract with intermediate profiles were also registered and chemometric tools such as the principal components and cluster analysis showed a noticeable potential for determining the nature of the extracts
Segnalazioni floristiche italiane: (909), Astragalus penduliflorus Lam., specie nuova per il Lazio e per l’Italia peninsulare.
No full textContribution to floristic knowledge of Middle Latina Valley (Lazio - Central Apennines)
Full text linkIn this paper the Authors show the preliminary results of a floristic research on the Latina Valley in Lazio Region. This research was carried out in the period 2009-2011. Amongst the about 500 species recorded, 50 entities are to be considered rare for the Latium region. In particular for the following taxa: Isoëetes duriei, I. hystrix, I. velata, Exaculum pusillum, Cicendia filiformis, Radiola linoides, Bellevalia trifoliata this paper represents their first record for inland zones since at present they were known for coastal areas only
Notulae alla checklist della flora vascolare italiana 11. 1803. Alchemilla cinerea Buser
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Hydrophobic tannin foams
No full textIndependently, from the formulation and the production method, tannin foams have always a strong affinity for water. Applying a surface heat treatment with infrared beams, it was possible to significantly decrease the water absorption of these materials. In particular, it was observed that treating the foam surface for 60 s with 12.8 or 16.0 kW m-2 IR beam energies, the drop absorption time increased up to 10 times. Similar effect was observed also when lower energies were applied for longer exposures. The spectroscopy investigation of the surface has highlighted a decreasing of hydroxyl group and an increase of aromatic character because of the partial carbonisation of the material, which explains the improved hydrophobicity
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