Biodegradable Polymers Blends

B iodegradability Biodegradable blends Biodegradable polymers Biomedical IPN... 

He, W, Yong, T., Teo, W.E., Ma, Z.W. and Ramakrishna, S. 2005a. Fabrication and endo-theliahzation of coUagen-blended biodegradable polymer nanofibers Potential vascular graft for blood vessel tissue engineering. Tissue Ens. 11 1575-1588. 

He, W., T. Yong, W. E. Teo, Z. Ma, and S. Ramakrishna (2005b). Fabrication and endotheliahzation of coUagen-blended biodegradable polymer nanofibers potential vascular graft for blood vessel tissue engineering. Tissue Engineering 11(9-10) 1574-1588. 

Many research efforts in laboratories and companies have been invested on blending biodegradable polymers in order to substitute nonbiodegradable polymers. 

Thermosetting polymer blends Biodegradable polymer blends... 

Biodegradable polymers and plastics are readily divided into three broad classifications (/) natural, (2) synthetic, and (J) modified natural. These classes may be further subdivided for ease of discussion, as follows (/) natural polymers (2) synthetic polymers may have carbon chain backbones or heteroatom chain backbones and (J) modified natural may be blends and grafts or involve chemical modifications, oxidation, esterification, etc. 

Polymer blends, particularly olefins with biodegradable polymers, are gaining popularity as an approach to degradable packaging plastics. The materials are at best only partially biodegraded, but will lose form and bulk as the plastic disintegrates. This may be sufficient in landfill as volume diminishes, leaving room... 

Other uses of blends include controlled rate of fertilizer release(77) based on ethylene/vinyl acetate/carbon monoxide polymers which is U.V. sensitive, polyolefin blends with any biodegradable polymers,(78) and polyolefins blended with metals and autoxidizable substrates. (79) Doane and co-workers(80) at the U.S.D.A. have used grafted starches in many applications, including soil stabilization. 

Biodegradable plastics have been used on an industrial scale since the end of the 1990s when BASF launched Ecoflex . This is a fossil-based, man-made polyester but yet is completely biodegradable due to its chemical structure. This structure is also the reason why Ecoflex combines excellent mechanical properties with the good processability of synthetic thermoplastics. Ecoflex is the preferred blend partner for bio-based and biodegradable polymers, which typically do not exhibit good mechanics and processability for film applications by themselves. Ecoflex therefore is a synthetic polymer that enables the extensive use of renewable raw materials (e.g., starch). 

No clear data are given to indicate that these blending partner polymers have a supporting effect on the PVA biodegradability in the resulting composite material. 

Sua J-E, Yuanb XY et al (2010) Properties stability and biodegradation behaviors of soy protein isolate/poly(vinyl alcohol) blend films. Polym Degrad Stab 95 1226-1237... 

Boesel, L. F., Mano, J. F., Elvira, C., San Roman, J., Reis, R. L. (2003). Hydrogels and hydrophilic partially degradable bone cements based on biodegradable blends incorporating starch. In E. Chiellini (Ed.), Biodegradable Polymers and Plastics. Kluwer Academic, Dordrecht. 

Blending, Grafting and Copolymerisation with Biodegradable Polymers and Additives... 

There is also US research interest in using pectin in polymer applications. Pectin is a complex plant cell wall heteropolysaccharide (based on galactose, rhamnose, arabinose and xylose) that can be blended with synthetic polyvinyl alcohol (PVA) to produce biodegradable polymers with a wider range of properties than those of starch-based polymers alone. The new pectin/PVA biodegradable polymer should be capable of replacing conventional PVA applications in blow-moulded, extruded, film and injection-moulded applications. 

A particular mention goes to Mater-Bi, produced by Novamont, who have revolutionised starch-based biomaterials for two decades. The commercial success of this biodegradable and biocompostable plastic relies on two main factors the scale economy that allows the reduction of costs, and the diversity of formulations to develop different end products (plastic bags, tableware, toys, etc.). More than 210 references in Chemical Abstracts are available on this (registered) keyword, and the number of patents related to different formulations and developments is also impressive. Mater-Bi can be essentially described as a blend of starch with a small amount of other biodegradable polymers and additives. The actual compositions are still known only by a very few people. 

Product development and improvement has a crucial role to play in the further development of the biodegradable polymers market. These include development of more reliable and lower cost raw materials for manufacture of biodegradable polymers, improvement in performance properties vis-a-vis standard thermoplastics, improvement in processing performance and development of new polymers and blends. 

In 2003, the average price of starch blends was around 3.0-5.0 per kg. In 2005, the average price range of starch blends was down to 1.5-3.5 per kg. PLA is now being sold at prices between 1.37-2.75 per kg compared to a price range of 3.0-3.5 per kg three years ago, and is now almost price competitive with PET. The average cost of an aliphatic aromatic co-polyester has fallen from 3.5-4.0 per kg in 2003 to 2.75-3.65 per kg in 2005. Prices are expected to fall further for all biodegradable polymer types over time as production volumes increase and unit costs fall. 

Starch based biodegradable polymers (including modified starch blends)... 

Meanwhile, Fujitsu and Toray Industries have developed the first large-scale notebook computer housing based on polylactic acid biodegradable polymers. The housing is moulded of a specially developed PLA/polycarbonate blend that provide the required heat and flame resistance. 

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

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