Page 328 - Handbook of Properties of Textile and Technical Fibres

302 Handbook of Properties of Textile and Technical Fibres

used in aerospace and automotive industries (Chowdhury et al., 2006). In recent years,
the use of plant fibers to replace conventional fibers as reinforcement in polymer com-
posites has gained popularity in many industrial applications due to increasing envi-
ronmental and ecological issues (Assarar et al., 2011; Bodros et al., 2007). The
fibers extracted from plants have been used for thousands of years; they are naturally
available resources, popular among users who are highly health conscious, and these
fibers are considered as valuable raw materials for many applications (Palanikumar
et al., 2016). Flax, hemp, jute, sisal, and bamboo are the most popular reinforcement
materials for biocomposites because they are cost-effective, have low density with
high specific strength and stiffness, and are readily available (Corrales et al., 2007;
Herrerafranco and Valadezgonzalez, 2005). Nevertheless, plant fibers also possess
some negative characteristics, i.e., they are highly hydrophilic and their properties
are strongly dependent on the climate, location, and weather; so it is difficult to predict
their respective material properties (Di Bella et al., 2010). Plant fibers also have a com-
plex structure, consisting of cellulose, hemicelluloses, pectin, lignin, and other compo-
nents (Bos et al., 2004). These fibers as composite reinforcement are not considered
only in the form of monofilament configurations (Van de Weyenberg et al., 2003).
The properties of hemp, jute, banana, kenaf, rami, and sisal fibers are presented in
Table 9.1.

9.2 Plant growth and harvesting techniques

The plants providing useful reinforcing fibers are usually well adapted to a wide range
of soil types; however, they are best grown in well-drained sandy loam fertile sites,
warm tropical or subtropical climate without undue rains and wind, hence they are ver-
satile plants. The plant’s sensitivity to frost is an important consideration when select-
ing a suitable site. It is important to plant into a fine, well-prepared seedbed to provide
good seed-to-soil contact for germination. The crop is grown in dense strands to limit
branching and promote the development of fibers in the main stem. Major fiber plants
are commercially cultivated in more than 20 countries; however, more than 95% of
total production is from China, India, Thailand, Pakistan, Indonesia, Japan, Vietnam,
and Malaysia (Ashori et al., 2006; Mambelli and Grandi, 1995). It was noticed that
50% reduction in stem growth as compared with the well-watered crop, and it can
be determined both by lower development of the crop awning and by the low effi-
ciency of utilization of intercepted light (Mambelli and Grandi, 1995). The bark con-
tent of the stem varied in relation to crop age and genotype and increased with time.
Cellulose content in the bark was affected by harvest date, ranging from 54% to
56% at early harvest and midharvest to 61.6% at the latest harvest, and by irrigation,
which favored a similar increase. Positive relationships (between 0.64 and 0.74) were
found between growth traits (total and stem dry yield, stem height, and basal stem
diameter) and cellulose accumulated in the bark. For animal bedding material made
of plant core, an important aspect of this application is the high moisture absorption
capacity of the material (Lips et al., 2009). To produce enough biomass of high quality