Lignin«based fillers

As it can be observed, the thermal decomposition for the starch-lignin based fillers composite materials can be divided into three individual stages moisture... 

Delignified cellulose is used as a commercial WPC filler in only one form, namely as a constituent of Biodac , in GeoDeck deck boards. It is delignified by virtue of chemical treatment of wood pulp for papermaking applications. All other cellulose-based fillers for WPC, such as wood flour, sawdust, and rice hulls, are natural materials, containing cellulose, hemicellulose, and lignin. 

Panthapulakkal and Sain [10] reported better interfacial bonding between wheat straw fibers to HOPE compared to corncob and corn stalk fibers. They attributed this to more-lignin type and carbon rich hydrophobic surface of wheat straws compared to the other agro-based fillers. They observed higher percentage of silica on the wheat straw fiber surface than the other fibers. 

Hatakeyama T, Izuta Y, Hirose S, Hatakeyama H (2002) Phase transitions of lignin-based polycaprolactones and their polyurethane derivatives. Polymer 43 177-1182 Hatakeyama H, Tanamachi N, Matsumura H, Hirose S, Hatakeyama T (2005) Biobased polyurethane composite foams with inorganic fillers studied by thermogravimetry. Thermochim Acta 431 155-160... 

Fillers are relatively inert materials that usually add bulk but when well chosen, they can enhance physical and chemical properties. Many natural and synthetic materials are used as fillers today. These include polysaccharides (cellulosics), lignin, carbon-based materials, glass, and other inorganic materials. 

Organic Extenders. Organic extenders are primarily of two types (1) fillers derived from organic materials and (2) low-cost, naturally occurring or synthetic resins. Of the first type, wood flour, shell flour, and other cellulosic fillers are the most common. They also provide a margin of mechanical property reinforcement because of their relatively high aspect ratio. Of the resinous types these are petroleum-based derivatives as well as soluble lignin and scrap synthetic resins. 

Classification of fillers can also be based on ttreir chemical form [28,29] as shown in Table 1.4. Organic fillers fall within the subcategory of cellulosics, lignins, proteins and s)mthetics. On the other hand, inorganic fillers include carbonates, oxides, silicates, sulfates, carbon, metal powders and so on. 

Proposed polysaccharide-derived materials as biodegradable fillers include a variety of starches, cellulose, lignin, sawdust, casein, mannitol, lactose, and other materials. These fillers have been tried in compositions of as much as 80% in a wide range of synthetic resins, including PE, PP, PS, ethylene-acrylic acid copolymers, PVC, and vinyl alcohol copolymers. Often additional additives such as fatty acids and processing aids are incorporated to improve the biodegradability of the finished product. Starch-based polymers are discussed further in Chapter 3 of this handbook. 

Kosikova, B., Osvald, A., and Krajcovicova, J. (2007) Role of lignin filler in stabilization of natural mbber-based composites. J. ApjA. Polym. Sci., 103, 1226-1231. 

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