Isolation of Cellulose Nanowhiskers from Kenaf Fiber - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 188

Chapter 17
isolation of Cellulose Nanowhiskers from Kenaf
Fiber
Hanieh Kargarzadeh, SitiYasmine, Z. Z., Ishak Ahmad,
and Ibrahim Abdullah
iNtroduCtioN
Recently, there has been wide interest in producing nanocellulose from natural fiber
to replace the synthetic fiber. This phenomenon is caused by the urge and awareness
from the society towards the green environment. Furthermore, the excitement is due
to the extraordinary properties of the materials because of the nanosize effect of the
reinforcement.
Natural fibers usually consist of cellulose, hemicelluloses, lignin, pectin, and waxy
materials. It has good mechanical properties and can compete the strength and mod-
ulus of the synthetic fiber (Mallick, 1988; Mohd. Sapuan, 1999). Unlike synthetic
fiber, natural fiber has more advantages such as low density, lightless, non-toxic, non-
abrasive, biodegradable, high flexibility level, good dynamic mechanical, electrical
and thermal properties to compared with other commercial fibers and available as
abundant nature materials in large quantity which makes the interest for the researcher
to replace the synthetic fiber (Bondeson and Oksman, 2007; Fahmy and Mobarak,
2008; Franco and Gonzalez et al., 2005; Kentaro et al., 2007; Roohani et al., 2008;
Seydibeyoğlu and Oksman, 2008; Sun Young Lee et al., 2009).
Kenaf or Hibiscus cannabinus is a plant that belongs to the Malvaceae family. In
Malaysia, kenaf is cultivated for its fiber due to the good weather, and the support and
encouragement from the government to replace the tobacco plantation. This plant has
a single, straight, and branchless stalk. Kenaf stalk is made up of a core and an outer
fibrous bark surrounding the core. The fiber derived from the outer fibrous bark is also
known as bast fiber. Kenaf bast fiber has superior flexural strength combined with its
excellent tensile strength that makes it the material of choice for a wide range of ex-
truded, molded and non-woven products.
Cellulose is the main component in natural fiber which this linear semi crystallite
polysaccharide is built up of repeating unit of D-glucopyranose that consist three hy-
droxyl groups. The diameter of this fibril is ranged from 5 till 10 nm, meanwhile, the
length depends on source from which the cellulose is obtained (Xue Li et al., 2007;
Yousef Habibi et al., 2008). Extraction of cellulose from the natural fiber and applied
as filler in nano range sized has find its place not just among the researcher but also to
the industry sector.
One way to obtain cellulose whiskers is by acid hydrolysis where the cellulose is
exposed to sulfuric acid for a controlled period of time and temperature. This process