Starch-Based Materials on the Market

Thermoplastic starch can also be blended with polyolefins [131 ]. In this case about 50% of thermoplastically processable starch is mixed with 40% of polyethylene and 10% of ethyl acrylate-maleic anhydride copolymer. During this mixing process an esterification reaction takes place between the maleic anydride groups in the copolymer and the free hydroxyl groups in starch. 

Other studies have been performed on polyamide/high amylose [73,132,133] and acrylic copolymers/high amylose starch systems [73, 133, 134]. The problem of partial biodegradability and a too high sensitivity to humidity persists. 

Starch/cellulose derivative systems are also reported in other publications [126, 130, 135,136], particularly, cellulose butyrate/starch blends in presence of glycerine and epoxidized soybean oil [135]. 

The combination of starch with a soluble polymer such as polyvinyl alcohol (PVOH) and/or polyalkylene glycols has been widely considered since 1970 [137]. In recent years the system, thermoplastic starch/PVOH has been mainly studied for producing starch-based loose fillers as a substitute for expanded polystyrene [138-144]. As an example, Altieri and Lacourse developed a technology based on hydroxypropylated high amylose starch containing small amounts of PVOH for improving foam resiliency and density [138-142]. In this case loose fillers were produced directly by a twin screw extruder. 

The two leading producers of starch-based biodegradable polymers are Novamont, with Mater-Bi, and Warner-Lambert s Novon Products Group. 

The largest share in terms of volume corresponds to the starch-based plastic market. The main applications are compost bags, shopping bags, loose-fill packaging and mulch films. 

Plantic Technologies Ltd is an Australian research company that offers products for thermoforming based on hydroxypropylated nongenetically modified high amylose corn starch. Its production capacity is of 7500 ton/year [134]. 

BIOP Biopolymer Technologies Ag entered the market with a starch-based material containing an additive consisting of a vinyl-alcohol/vinyl-acetate copolymer [135]. The material is sold under the Biopar trademark. 

Cardia Bioplastics Ltd (Australia) in 2008 acquired the resins business established in 2002 as Biograde Limited. Their Product Development Centre and manufacturing plant is in Nanjing, China. Cardia Bioplastics Ltd commercializes a biomaterial obtained mixing starch and biodegradable polyesters in the presence of a transesterification catalyst [136]. 

After more than 20 years of research and development, starch-based materials have achieved specific in-use performances and can replace traditional plastics in different application sectors. They are able to offer original solutions both from the technical and the environmental point of view. 

In 2003 the market of destructurised and complexed starch-based bioplastics accounted for about 30000 tons/year, 75% of which was for packaging applications and included soluble foams for industrial packaging and films for bags and sacks. The market share of these products accounted for about 70% of the global market of bioplastics [174]. 

Leading producers with well established products in the market are Novamont, National Starch (main Novamont partner and licensee in the sector of loose-fills and of foamed sheets), and Biotec. Following the recent start-up of its third line dedicated to the production of Mater-Bi film grades in Terni, Novamont s internal production capacity is of 20000 tons/year. The total capacity, including the network of licensees in the sector of loose fills, is of about 35000 tons/year. The technology for the production of starch-based loose fills is licensed together with National Starch and Chemical Co. 

The wide patent portfolio of Novamont covers the technologies of complexed starch developed by Novamont and of destructurised starch developed by Warner-Lambert and acquired by Novamont in 1997 after the exit of Warner-Lambert from the market in 1993. Moreover, in August 2001, Novamont acquired the film technology of Biotec which included an exclusive license of the Biotec s patents on TPPS in the sector of film [174]. 

Biotec, the German company which acquired in 1994 the patents of Flimtera, was acquired by Essem Kashoggi Industries (EKI) in 1998. Biotec, after the sale of the film business to Novamont in 2000 offers materials for food serviceware (cutlery, plates, cups) and for pharmaceutical applications under the Bioplast trademark. Its production capacity is of 2000 tons/year. 

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This chapter reviews the main results obtained in the fields of starch-filled plastics and thermoplastic starch, paying particular attention to the concepts of gelatinization, destructurization, extrusion cooking, and the use of com-plexed starch in specific synthetic polymers. Aspects such as processability, the physicochemical and physicomechanical properties and the biodegradation behaviour of starch-based materials on the market are briefly considered. 

Commercial water-resistant starch based bioplastics are produced by using fine molecular blends of biodegradable synthetic polymers and starch. These materials are made with gelatinised starch (up to 60-85%) and hydrophilic synthetic polymers (e.g. ethylene vinyl alcohol copolymer) or hydrophobic synthetic polymers (e.g. polyeaprolactone or Ecoflex ) and compatibility agents (Fritz et al., 1994). The most important starch based material on the market is proposed by Novamont as Mater-Bi . 

Starch is isolated from plant sources by various methods (Ratnayake and Jackson, 2003 Zobel, 1992). The method of starch isolation depends on the nature and composition of the raw material source. Most food starches are isolated and purified on a commercial scale and then used as ingredients by food manufacturers. Commercial food starches are generally classified based on both botanical origin and functionality. With the increasing availability of modified starches prepared for specific food applications, starch manufacturers tend to emphasize and market starch with a secondary focus on botanical source. In fact, for food... 

Starch is still quite widely used as an adhesive in our modern, high tech world. Its adhesive properties are developed differently for different products, and starch-based adhesive is used in a large variety of applications. From the standpoint of its being a renewable resource, a reliable performer, and a low-cost raw material, starch would seem to be an adhesive ingredient on the market for a long time into the future. 

It is also important to mention materials with high starch content, or based exclusively on starch. The main examples of this family of products are expanded TPS compositions such as those patented hy the National Starch Chemical Investment Corp [78] used in replacement of expanded polystyrene. This was one of the first commercial TPSs placed on the market and is still sold today in growing quantities. Its success is due, not only to the replacement of a synthetic polymer hy a hiodegradahle one, hut also to its good performance and because its production cost is lower than that of expanded polystyrene. 

Biodegradability does not depend on the origin of the raw materials but on the chemical structure. Thus, materials from renewable as well as from synthetic resources are on the market. While cellophane, starch and polyhydroxybutyrate have existed on the market for many years, newer developments include poly (L-lactide) as well as numerous fossil based biodegradable polymers, e.g. copolyesters. 

It follows a short description of starch-based materials (Table 1) and polyesters (Table 2) That are either already on the market or at an advanced development stage. 

The results obtained in the field of thermoplastic starch in combination with polymers or copolymers of vinyl alcohol with aliphatic polyesters and copolyesters in terms of biodegradation kinetics, mechanical properties and reduced sensitivity to humidity make these materials ready for a real industrial development starting from film and foam applications. The present global market is around 12000 tons/year. Main producers are Novamont with Mater-Bi trade-mark, ENPAC and National Starch. The tensile properties of films made of two Novamont s Mater-Bi grades are reported in Table 3, in comparison to these of low density polyethylene (LDPE). Figs. 6-7 show applications of Mater-Bi starch-based materials now on the market. 

Today, biodegradable biopolymers are available on the market, at different levels of development, and are mainly carbohydrate-based materials. Starch can be physically modified and used alone or in combination with other polymers, or it can be used as a substrate for the fermentation and production of polyhydroxyalkanoates or lactic acid, is then transformed into polylactic acid through standard polymerisation processes. An alternative option is represented by vegetable oil-based polymers. 

Over the last 25 years a number of biopolymeric materials entered the market place that are based on renewable resources and are compostable. Especially cellulose, starch, sugar, vegetable oils and their secondary products, as well as some lignins and proteins are renewable resources that have been used as base components for bio-based and biodegradable biopolymers. 

Polylactide (PLA) and thermoplastic starch-(TPS) are two of the most promising biobased materials currently available on the market. The expected rise in the cost of petroleum-based commodities in the next decades opens bright perspective for these materials. Their biodegradability and compostability is also seen as an asset in applications that are difficult to recycle. 

The biodegradable polymer available in the market today in largest amounts is PEA. PEA is a melt-processible thermoplastic polymer based completely on renewable resources. The manufacture of PEA includes one fermentation step followed by several chemical transformations. The typical annually renewable raw material source is com starch, which is broken down to unrefined dextrose. This sugar is then subjected to a fermentative transformation to lactic acid (LA). Direct polycondensation of LA is possible, but usually LA is first chemically converted to lactide, a cyclic dimer of LA, via a PLA prepolymer. Finally, after purification, lactide is subjected to a ring-opening polymerization to yield PLA [13-17]. 

The emergence of TPS with tunable properties, by using continuous reactive extrusion, can lead starch to a new position in the market of thermoplastic materials based on renewable resources with functional properties such as biodegradabitly. 

The book is organized in several chapters and deals with the most important biopolymer classes like the different polysaccharides (starch, cellulose, chitin), lignin, proteins and (polyhydroxy alkanoates) as raw materials for bio-based plastics, as well as with materials derived from bio-based monomers like lipids, poly(lactic acid), polyesters, polyamides and polyolefines. Additional chapters on general topics - the market and availability of renewable raw materials, the importance of bio-based content and the aspect of biodegradability - provide important information related to all bio-based polymer classes. 

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