Tannin

“A tannin (a.k.a. vegetable tannin, i.e. a type of biomolecule, as opposed to modern synthetic tannin) is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids. The astringency from the tannins is what causes the dry and puckery feeling in the mouth following the consumption of unripened fruit or red wine.[1]Likewise, the destruction or modification of tannins with time plays an important role in the ripening of fruit and the aging of wine.”

“Tannins have molecular weights ranging from 500 to over 3,000 (gallic acid esters) and up to 20,000 (proanthocyanidins). Tannins are incompatible with alkalis, gelatin, heavy metals, iron, lime water, metallic salts, strong oxidizing agents and zinc sulfate, since they form complexes and precipitate in aqueous solution.”

(Wikipedia, Tannin, 4/27/2011)

Natural Polymers
NR /Tannin IPN
Polymers /Resins
Tannin Nanocomposites