Biomedical Engineering Reference
In-Depth Information
10
Cellulose Nanocrystals in Polymer
Matrices
John Simonsen and Youssef Habibi
10.1
Introduction
Polymer composites have been with us since Leo Baekeland put wood flour in phenol-
formaldehyde resin and invented 'Bakelite' in 1907 (Rosen 1993). Since then we have
seen many improvements in composite technology, and the latest in this string of develop-
ments is polymer nanocomposites. While polymer nanocomposites are not new, e.g. car-
bon black in automobile tires is a nanocomposite and has been with us for approximately
100 years (Kohjiya
et al
. 2005), they have received increasing attention from researchers
over the past
20 years and many new developments have resulted (Koo 2006).
While the use of cellulose nanocrystals (CNXLs) has been studied by a number of
researchers, mostly from the natural products community, for the past several years,
CNXL-filled polymer composites still represent only a tiny fraction of the research effort
being expended in the general area of polymer nanocomposites. This research has been
recently reviewed by several authors (Azizi Samir
et al
. 2005a; Dufresne 2006; Kamel
2007; Dufresne 2008). In this chapter, we will focus primarily on summarizing the
results obtained to date on a few polymer systems, carboxymethyl cellulose, poly(vinyl
alcohol) and polysulfone, with an added look at transport properties.
∼
10.2
Background on CNXL Material Science
Cellulose is the largest volume polymer on earth. It is contained in virtually all plants and
is produced by certain bacteria and small sea animals. Regardless of its source, cellulose
is a semi-crystalline high molecular weight homopolymer of
β
-1,4 linked anhydroglucose
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