NODAX

Noda, L, Satkowski, M.M., Dowrey, A.E. and Marcott, C. 2004. Polymer alloys of nodax copolymers and poly(lactic acid). Macromolecular Bioscience 4 269-275. 

BAK, Bioceta, Biomax, Bionelle, Biopol, Cortec, CPLA, Easter Bio, Ecoflex, Mater-Bi, Metabolix, Nature Works PLA, Nodax, PEC (polyester carbonate), PLA, Sky Green BDP... 

Noda I, Lindsey SB, Caraway D (eds) (2010) Nodax class PHA copolymers their properties and applications. In Microbiology monographs, vol 14. Springer, Heidelberg, pp 237-255... 

Figure 7.2. Chemical structures of poly-3-hydroxybutyrate (PHB A), PHB-co-3-hydroxyvalerate (PHB/V B), PHB-co-4-hydroxybutyrate (PHB/4HB C), Medium-chain-length polyhydroxyalkanoate (mcZ-PHA D), NODAX (E). Note The Rx side chain is generally composed of a straight chain aliphatic hydrocarbon from 3 to 11 carbons in length (mc/-PI IA) or 3, 5,7 or 9 carbons in length (NODAX ).

There were a number of efforts to commercialise PHA, notably by ICI in the 1980s and early 1990s, and by Monsanto in the mid 1990s. However, these attempts were largely unsuccessful due to the high cost and very limited processability and properties. In recent years, these deficiencies have been largely overcome most notably by Metabolix and by Procter Gamble s Nodax business unit, which both specialise in PHA materials development. 

PHA biodegradable polymers are still largely at the development stage of market development, although there a few commercial applications available. The main candidates for commercialisation are Biopol PHBV, being developed by Metabolix, and Nodax PHBH, marketed by Procter Gamble. 

Procter Gamble is the other leading pioneer on the field of PHA biodegradable polymers. The Nodax biopolymers are based on the copolymer PHBH, a copolymer polyester of 3-hydroxybutyric and 3-hydroxyhexanoic acid. The higher the 3-hydroxyhexanoic acid comonomer component, the more flexible... 

Nodax C4/C6 is said to be a natural fit for injection moulding and extrusion of sheet or film. The polymer has mechanical properties similar to a polyolefin and surface properties much like PET, including high receptivity to printing inks and dyes. Adhesion to LDPE and PP is good enough to avoid tie layers in multi-layer structures. Nodax s oxygen barrier property approaches that of EVOH. 

In summary, the most important properties of Nodax polymers according to P G are its anaerobic and aerobic degradability, hydrolytic stability, good odour and oxygen barrier, surface properties are ideal for printing, wide range of tailored mechanical properties and excellent miscibility with other resins to further optimise properties. 

Procter Gamble claim potential applications for their Nodax polymers are as follows ... 

Nodax has the benefit of degradation in septic systems, which offer possibilities for application in feminine hygiene products such as wipes and tampon applicators. These flushable products may exist in the form of paper coatings, fibres, films and foams. 

Nodax properties are suitable for short life applications include medical surgical garments and disposable wipes and also some long life applications include automotive upholstery and carpet, where there is growing industry interest in use of degradable materials. 

The thermal and surface properties of Nodax offer potential for binding of nonwovens such as PET Nodax could be applied in either a solid particulate or latex form to thermally bonded nonwovens. Nodax could also provide high wet strength to tissue and other papers, while at the same time preserving aesthetics and disposal options. 

Nodax combination of odour barrier, hydrolytic stability and compostability characteristics offer potential as compostable paper or plastic bags as well as agricultural film. 

The combination of odour barrier, sealability and printability provides potential for Nodax in flexible packaging. Nodax is a soft and pliable, yet reasonably transparent polyester resin. Polyester films have better printability because of their higher surface energy. For example, a thin layer of PET is often reverse-printed and then laminated over polypropylene. Nodax can substitute for both the polypropylene and polyester layers, since it can be converted like a polypropylene film and is already printable. 

Nodax properties of barrier, heat and dielectric sealability, and printability offer potential as lidding or tub stock for thermoformed articles. 

Nodax coating can also be applied to foodservice articles such as cups, plates, and placemats. When it comes to disposal, Nodax is complimentary with composting of food waste. Its fast anaerobic degradability means these materials can be disposed of in marine or other low oxygen environments. The ideal market opportunities are found in closed loop environments such as theme park landfills, cruise and navy ships. 

There are growing opportunities for polymer-based synthetic papers for labels where the printability and reduced environmental impact of Nodax polymers could play a role. 

Nodax has superior biocompatibility compared to other bioresorbable plastics, which makes the material suitable for some medical applications such as drug release, bone regeneration, and nerve guidance. 

Nodax can be blended with other biodegradable polymers such as polylactic acid and thermoplastic starch for improved processing performance. 

PHB producers expect continued progress in fermentation processes and identification of lower cost feedstock to provide more reasonable material costs for niche markets. Longer term, crop-based production has potential to drive PHB costs to more competitive levels from improved productivity. P G for example, is investigating the manufacture of Nodax by plant-grown methods. The supplier states that this method could reduce Nodax prices to between 1.0-2.0 per kg. 

In 2004, Procter Gamble formed a joint development agreement with Japan s Kaneka Corporation for the commercialisation of Nodax biodegradable polymers. The companies will develop cost-effective ways of producing Nodax through fermentation and make the polymer easier to process so it can be used in a wider range of applications. 

K.M. Schreck, M.A. Hillmyer, Block copolymers and melt blends of polylactide with Nodax microbial polyesters preparation and mechanical properties, J. Biotechnol. 132 (3) (2007) 287-295. 

Copolymers of scl and mcl PHA possess useful and flexible mechanical properties they are the preferred materials for application development. A successful example is the PHBHHx that was produced on an industrial scale (Chen 2009b). US-based Procter Gamble has trademarked scl and mcl PHA copolymers of C and Cg-Cj2 as Nodax (Noda et al. 2009). 

Mittendorf V, Robertson EJ, Leech RM, Krtiger N, Steinbtichel A, Poirier Y (1998) Synthesis of medium-chain-length polyhydroxyalkanoates in Arabidopsis thaliana using intermediates of peroxisomal fatty acid P-oxidation. Proc Natl Acad Sci USA 95 13397-13402 Noda I, Lindsey SB, Caraway D (2009) Nodax class PHA copolymers their properties and applications. Microbiol Monogr. doi 10.1007/978-3-642-03287-5 10 Pederson EN, McChalicher CWJ, Srienc F (2006) Bacterial synthesis of PHA block copolymers. Biomacromolecules 7 1904-1911... 

Fig. 3 Packaging products made from poly[( )-3-hydroxybutyrate-co-(i )-3-hydroxyhexanoate] (Nodax ) (photos from Isao Noda of P G, USA)...

Nodax Class PHA Copolymers Their Properties and Applications... 

The general molecular stracture of the so-called Nodax class PHA copolymers is a random copolymer of predominantly (l )-3-hydroxybutyrate (3HB) and other (R)-3-hydroxyalkanoate (3HA) comonomer units, as shown schematically in Fig. 1. The secondary 3HA comonomer units must have side groups consisting of at least... 

Fig. 1 Molecular structure of Nodax class polyhydroxyalkanoate (PHA) copolymer. The value of X is between 2 and 50%...

The motivation behind the molecular design of Nodax class PHA copolymers closely follows that of the well-known industrial polyolefin linear low density polyethylene (LLDPE). LLDPE is a random copolymer of ethylene with a small amount of a-olefin units, such as 1-butene or 1-hexene, which will result in the formation of the polymer chain structure with mcl alkyl side group branches. In a similar manner, one can envision the possibility of creating a polymer structure of LLDPE with a PHA backbone having short alkyl side chains, as depicted in Fig. 2. 

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