Ball-milling Promoted Chemical Bonding between Cellulose and Plastics - Ball Milling Towards Green Synthesis: Applications, Projects, Challenges - page 233

(f)

1733 1717

(e)

(d)

1735

1719

1737
1 721 1713

(c)

(b)

(a)

1792

1713

1860 1830 1800 1770 1740 1710 1680

Wavenumber/cm -1

Figure 9.22 IR spectra of MPE (a), dried MPE (b), UMCom (c), MCMix (d), dried

MCMix (e), and MCCom (f).
Reprinted from ref. 41.

extensive formation of ester bonds between FC and MPE, which is quite
different from melt-mixing. It is remarkable that such mechanochemical
esterification proceeds even between high-crystalline cellulose and MPE in a
solid state by ball milling, as confirmed by the results of the MCMix sample.
Ball milling of FC changes drastically its crystalline state into an amorphous
one, as clearly shown in Figure 9.23, and this indicates that crystalline FC is
so activated as to generate a great number of free OH groups on the surfaces
of fine particles of amorphous cellulose. Of special interest, the ball-milled
FC, even if melt-mixed with MPP, can generate ester bonds with MPP. 42
From the aforementioned results, we can describe a mechanism for the
mechanochemical compounding of crystalline cellulose with MPE by ball
milling: (1) activation of cellulose to yield free OH groups and (2) reaction of
resultant free OH groups with MA grafts of MPE to generate ester bonds. The
activation of cellulose is essential for the compounding of crystalline cellu-
lose with MPE through ester bonds. Accordingly, such esterification can
proceed extensively by ball milling cellulose and MPE or even by ball milling
only cellulose in advance to melt-mixing with MPE, only if cellulose particles
have a number of free OH groups on the surfaces.