Page 346 - Biodegradable Polyesters

324 13 Biodegradable Polyester-Based Blends and Composites

applications, which include automobile applications, packaging, and construc-
tional applications. One of the key area of application of these composites is
in the automotive industry because of their green material initiative combined
with a range of specific properties of natural fiber polymer composites that meet
the criteria for several automotive parts. For specific consideration, a material
upgrade in the door panels of the Mercedes-Benz E-class vehicle model was
performed with flax/sisal fiber-mat-embedded epoxy resin composite because of
its desired mechanical properties [15]. In addition, it led to a noteworthy weight
reduction of 20% in the door panels without compromising vehicle safety [16]. It
is noteworthy that Rieter Automotive won the JEC Composites Award 2005 for
producing natural fiber reinforced thermoplastic composites for an under-floor
module with incorporated aerodynamic, acoustic, and thermal functions [17].
Natural fibers such as coir, hemp, flax, bamboo, and sisal can also be combined
with synthetic fibers, predominantly E-glass, to produce required tensile strength,
elastic modulus, and elongation at failure. E-glass fibers serve as a reference
because of their extensive use in composite technology with many industrial
applications [18]. Consequently, to demonstrate the performance of a new type of
natural fiber composites for industrial use, comparison of properties with E-glass
fiber as the reference is often carried out.

13.2.3
Synthetic Fiber Reinforcements

®
The commonly used synthetic fiber reinforcements are aramid, Nomex ,nylon,
®
and Kevlar fibers [19]. The research and development in the fields of synthetic
fiber reinforced composites led to the development of aramid fibers. Further
research led to the invention of meta and para-aramids [20]. Para and meta refer
to the positions of the carboxylic and amine groups on the monomer ring. Nomex
[21] was produced in the early 1960s and its excellent thermal, chemical, and
radiation resistance [22, 23] led to extensive use in defensive clothing, insulation,
and as a substitute for asbestos [24]. Additional researches with this meta-aramid
(Nomex) led to the fiber recognized as Kevlar [25]. Kevlar is a para-aramid fiber
[26]. It was produced and trademarked by DuPont and became commercially
accessible in 1973. In the last two decades, the worldwide production and use of
aramids has been growing steadily.
Initially, Kevlar was used in car tires as reinforcement for the elastomeric matrix
(rubber); however, nowadays the most widely known application of Kevlar/epoxy
is in body armor [27]. Other uses include fireproof suits for firefighters, gloves, and
helmets [28]. Their high strength-to-weight ratio makes them more suitable for
use as reinforcement, for example, in composite materials primarily where flexure
properties are important, such as aircraft wings [29].
The cost of fiber reinforcement in composites is estimated to decrease con-
siderably with improved market share and demand. On the other hand, there
are applications even today where FRP reinforcements are expensive, such
as in aerospace applications. In the case of FRP composites, environmental