Page 342 - Handbook of Properties of Textile and Technical Fibres

Hemp, jute, banana, kenaf, ramie, sisal fibers 315

made of the surface modification of plant fiber by Mohanty et al. (2001). The perfor-
mance of the resulting biocomposites was also studied. The tensile properties of the
hemp fiber are given in Table 9.1. The stressestrain curve obtained by tensile tests
had a similar trend to that of jute fibers. The large variation of tensile properties be-
comes evident from these studies and is found with plant fibers, and this is unavoidable
as there are several factors that are uncontrollable in a large-scale setup (Nishino,
2004). The tensile properties of the hemp fibers were studied based on the age of
the plant and testing parameters (Pickering et al., 2007). It was found that a fully
matured plant had better tensile strength than the partly matured plant; it was also
found that the testing parameter and gauge length affected the tensile strength of the
hemp fiber (Pickering et al., 2007). The renowned automotive company, Bayerische
Motoren Werke (BMW), makes car parts out of hemp fiberereinforced composites
(Kandachar and Brouwer, 2001). A detailed review of hemp fiber and its composites
was carried out by Shahzad (2012).
Several authors propose different tensile properties of sisal fibers, and this variation
can be expected in plant fibers. The sisal fibers are used as reinforcements in thermoset
and thermoplastic matrices like the other plant fibers; and the mechanical, thermal,
viscoelastic, dielectric, water absorption, and morphological properties of the compos-
ites have been published (Bakare et al., 2010; Costa and d’Almeida, 1999; Joseph
et al., 1993, 2003; Rong et al., 2002; Chand and Joshi, 1994; Chand and Hashmi,
1993; Megiatto Jr. et al., 2009). Li et al. (2006) have evaluated and correlated the
compressive strength, flexural strength, toughness, specific gravity, and water absorp-
tion rate of hemp fiberereinforced composites with different compositions. The water
uptake and the linear specific gravity of the composites are gradually reduced by add-
ing the hemp fiber to a concrete matrix. They have observed that the fiber content by
weight is the important factor that affects the compressive and flexural strength of
hemp fiberereinforced composites. Hemp fiber has superior reinforcement properties
while increasing tensile properties and toughness in an alkali environment (Wang,
2002; Wang et al., 2001). Jute fibers absorb most water among the bast fibers. It is
one of the most studied fibers for reinforcements: epoxy composites (Mishra et al.,
2000), poly lactic acid composites (Khondker et al., 2006), polyester amide compos-
ites (Mohanty et al., 2000b), phenolic composites (Singh et al., 2000; Razera and Frol-
lini, 2004), etc. Water uptake and morphological analysis of the jute fibers were carried
out (Razera and Frollini, 2004). Fiber length dependence on impact strength in jute-
based composites was studied by Razera and Frollini (2004). There was more than
500% growth in use of jute fibers for car door panels from the year 1996e99 (from
4000 to 21,000 tons) (Lewington, 2003). A detailed review of jute fibers and its com-
posites was carried out by Mohanty and Misra (1995).

9.6.3 Morphological properties

Morphological analysis is very common among plant fiber composites’ research so as
to study interfacial adhesion, pores, fiber pull-out, etc. Evaluation of fiber pull-out was
studied in detail by Sydenstricker et al. (2003). Oksman et al. (2002) studied scanning
electron microscopy images of sisaleepoxy composites. Fig. 9.3 shows the typical