Civil Engineering Reference
In-Depth Information
11.6.1
Acetylation
Kim
et al.
[158] reported that cellulose was partially acetylated to modify its physical
properties while preserving the microi brillar morphology in which material proper-
ties were crucially inl uenced by the degree of acetyl substitution [42]. According to
Ifuku
et al.
[159], transparency and hygroscopicity of cellulose/acrylic resin composite
materials were improved and reduced by acetylation, respectively, though the compos-
ites exhibited an optimum degree of substitution and were reduced in properties with
excessive acetylation. A study by Nogi
et al.
[160] found that acetylation improved the
thermal degradation resistance of cellulosic i bers. h e ef ect of biological exposure
(Figure 11.20) upon the properties of acetylated and surface-treated plant i ber-based
polyester composites was studied by Abdul Khalil and Ismail [161]. It was found that
acetylation exhibited superior bioresistance followed by silane, as well as cast resin
and glass i ber composites, in soil tests up to 12 months exposure. In other research
of Abdul Khalil
et al.
[162] , modii ed i bers were shown to have a smoother surface
compared to the unmodii ed ones, which was believed to be a factor in improving the
i ber-matrix adhesion.
11.6.2
Silylation
Isopropyl dimethylchlorosilane was used by Goussé
et al.
[163] for surface silylation
of cellulose microi brils resulting from the homogenization of parenchymal cell walls.
h ese authors claimed that microi brils retained their morphology under mild silylation
Figure 11.20
SEM micrographs of unmodii ed EFB composite: (A) severe degradation of unmodii ed
EFB, (B) acetylated EFB composite and (C) slight degradation of acetylated EFB composite (D) [161].
