This review discusses the effect of nanocellulose or lignocellulosic fibers introduced in starch films. A concise comparison in the mechanical and water absorption properties of the nanocellulose-reinforced starch originated from different plant species was made. It was found that most of these studies prefer solution casting as popular fabrication technique. Studies found nanocellulose generates positive results on mechanical and water uptake properties. The increment in tensile strength was reported between 1.08 to slightly higher than 2-fold while water uptake was decreased between 1.14 to 1.19-fold. In addition, the fibers also serves well as a reinforcement material for starch matric although not as competent as nanocellulose. Discussion on improvement in mechanical, water uptake, thermal, and biodegradation of lignocellulosic fiber-reinforced starch was presented in this chapter. This review also emphasizes potential uses of nanocellulose reinforced starch composite as a smart food packaging and bio-carrier in bio-delivery system where it contributes considerably to a better life.
TopIntroduction
Bio-composite complete the return of material used and energetic value back to the nature cycles when its production appropriately taking into account sustainable energy and chemical consumption starts from selection of raw materials, processing, service life of the product, up to waste management procedure (Vilaplana, Strömberg, & Karlsson, 2010). These efforts are important due to the fact that uncontrolled industrial development had imposed negative impact on the planet we live in. Some experts argue earth geology has been switched to a new geological era known as Anthropocene, where environmental equilibrium enjoyed by the earth and many lives inside it for as long as 10000 years were disturbed by - mostly human activity (Crutzen, 2002). Although the industrial revolution has led to economic prosperity and rise in living standard, but it also at the same time has imposed industrial pollution cost whenever earth's fragile nature is compromised. Therefore, in dealing with this issue, a concept inspired by the nature has been introduced to be infused into business management which is known as cradle-to-cradle concept (McDonough, Braungart, Anastas, & Zimmerman, 2003). This concept will give unimaginable benefit if material and energetic products and processes successfully optimized.
One of the many commercialized bio-composites is bio-composite made from cellulosic plant fiber. Driven by the increase in the price of timber resources, concern for the environment, competition and the availability of new sources of fiber neither from agricultural biomass nor wood residue, all these has led to increased demand for cellulosic bio-composite. Cellulosic bio-composite can be divided into two categories, namely fabricated from wood or non-wood resources. Both of them are made up by cellulose chains which are linear polysaccharides consist of 10,000 glucopyranose units (in woody plant) linked together by β-1-4-linkages, depicted by Figure 1.
Figure 1.
Chemical structure of cellulose; the arrows point to the cellobiose molecule which is the basic unit of cellulose (Habibi, Lucia, & Rojas, 2010)
These linear polymers align together to produce elementary fibril that further pack into microfibrils which are in turn assembled into fibers. The microfibrils range between 2 to 20 nm in diameter and length up to micrometer in size; they consist of alternating crystalline and amorphous domain. Crystalline domain is where cellulose chains are arranged in highly ordered while amorphous domain consist disordered cellulose chains (Moon, Martini, Nairn, Simonsen, & Youngblood, 2011). Table 1 demonstrated some example of wood and non-wood based cellulosic bio-composites for different properties and applications where the improvement on certain properties of polymeric materials has been recorded.