Practical Applications of Biodegradable Polymers

Polyvinyl alcohol can form complexes with many components, and so it can detoxify organisms. It is apphed in low-molecular-weight form - below 15 000- and is voided from the organism through the kidney. In addition, it is also used as a polymer carrier for plant protection (herbicides and pesticides) [44], 

The biodegradable polymers are used in three main areas medical, agricultural, and goods packaging. Intensive research in these fields has resulted in the development of commercial products. Because of their high specialization and greater unit values, medical appHcations have developed more rapidly than the others. 

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Poly(a-ester)s, the most expansively studied class of biodegradable polymer, contain aliphatic ester linkages in their backbone which can be cleaved hydrolytically. It is reported that mere aliphatic polyesters with practically small aliphatic chains between ester bonds can decompose over the time needed for the majority of the biomedical applications. Poly(a-ester)s demonstrate enormous diversity and synthetic flexibility and, depending on the monomeric units, can be synthesized from a variety of monomers via condensation polymerization and ring-opening routes [19]. Poly(glycolic acid) and the stereoisomers of poly(lactic acid) are the most expansively investigated poly(a-ester)s polymers. 

The extremely active academical and industrial research focused on the use of biodegradable polymers for agricultural applications has induced the introduction of several products to the market. These products based on biodegradable materials are supposed to be applied as mulching films, green houses sheets, laminates, and containers in agricultural practices and for application such as soil structurization and controlled release of chemicals such as fertilizers and herbicides. 

Degradable polymers destined for composting should, therefore, be modelled on the behaviour of lignin as far as possible [12]. Oxo-biodegradable polyolefins, particularly the polyolefins and polystyrene, have been shown to be particularly suitable for this application. They cannot, because of their chemical structures, ultimately produce any products other than carbon dioxide and water. The practical applications of these materials are the main focus of this Chapter and composting standards for degradable polyolefins will be discussed in Section 9. 

Applications in the Natural Environment. Considerable attention has been focused on degradable plastics especially in the natural environment. Depolymerization has a number of practical applications, including degradable plastics. In particular, the applications of biodegradable plastics have been extensively reviewed as the desirable polymer waste management (68-70). The depolymerization in the environment occurs by two distinct mechanisms... 

Poly(butylene succinate) (PBS) is an important member of biodegradable aliphatic polyester family. PBS and related copolymers have shown considerable promise for uses as environmentally biodegradable thermoplastics, as well as bioabsorbable/biocompatible medical materials (/). In both cases, practical applications require that the polymer possess a high molecular weight (M >20,000) so that it can have useful mechanical properties. 

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