Cellulose Fiber Reinforced Poly(lactic acid) (PLA) Composites - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 172

Chapter 16
Cellulose Fiber reinforced Poly(lactic acid) (Pla)
Composites
Nina Graupner and J ö rg M ü ssig
iNtroduCtioN
The demand for environmentally friendly products based on renewable raw materials
has increased in the last years. Examples of biodegradable materials include natural
fiber reinforced biopolymers (Anonymous, 2007; Avella et al., 2009; Bhardwaj and
Mohanty, 2007; Bledzki et al., 2009; Bodros et al., 2007; Cheung et al., 2009;
Nampoothiri et al., 2010). As an alternative to natural fibers, man-made fibers based
on renewable resources can be used as reinforcement. The advantage of the man-made
over the natural fibers is their reproducible quality; a disadvantage is the higher price
in comparison to for example bast fibers. An example of a man-made cellulose fiber
is lyocell which is regenerated from 100% wood cellulose in the NMMO process us-
ing an organic solvent N-methyl-morpholine-N-oxyde. The NMMO process is based
on the ability of amino oxide to dissolve cellulose under specific conditions. The cel-
lulose can be regenerated out of these solutions and the fibers are produced by a wet
fiber formation process (Albrecht et al., 1997). Lyocell fibers display special force
elongation characteristics. They combine a high tensile strength and a high elongation
at break in one fiber which is an advantage for the production of composites which
must display high tensile and impact strength at the same time. A typical force-elon-
gation curve of lyocell fibers in comparison to kenaf (bast fiber) and cotton (seed hair
fiber) is shown in Figure 1.
Figure 1. Force-elongation characteristics of kenaf, cotton and lyocell fibers.