The comparative solid state 13C CPMAS NMR spectra
of cornstarch, mimosa tannin, UF, cornstarch–UF
(10:90 w/w) and cornstarch–mimosa tannin–UF
(10:4:86 w/w) resins are shown in Fig. 5. The spectral
feature of cornstarch–mimosa tannin–UF (10:4:86 w/w)
resin are quite similar to those of cornstarch, mimosa
tannin and UF. With the present result, it is not possible
to ascertain if there interactions between mimosa tannin
and UFresin. Used method would be not definite enough to
identify chemical reactions between mimosa tannin and
UF resin. When small amounts of mimosa tannin are
added to a cornstarch–UF (10:90 w/w) resin, a reaction
takes place immediately, at ambient temperature, giving a
soft mass easily dissolved by fast stirring and the addition
of small amounts of water. Using MS, Pizzi [12] showed
that the –CH2OH groups of the UF resin react with resorcinolic A-rings of the flavonoid units while forming a methylene bridges (Fig. 6).
The comparative solid state 13C CPMAS NMR spectraof cornstarch, mimosa tannin, UF, cornstarch–UF(10:90 w/w) and cornstarch–mimosa tannin–UF(10:4:86 w/w) resins are shown in Fig. 5. The spectralfeature of cornstarch–mimosa tannin–UF (10:4:86 w/w)resin are quite similar to those of cornstarch, mimosatannin and UF. With the present result, it is not possibleto ascertain if there interactions between mimosa tanninand UFresin. Used method would be not definite enough toidentify chemical reactions between mimosa tannin andUF resin. When small amounts of mimosa tannin areadded to a cornstarch–UF (10:90 w/w) resin, a reactiontakes place immediately, at ambient temperature, giving asoft mass easily dissolved by fast stirring and the additionof small amounts of water. Using MS, Pizzi [12] showedthat the –CH2OH groups of the UF resin react with resorcinolic A-rings of the flavonoid units while forming a methylene bridges (Fig. 6).
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