Partially biodegradable polymers

ARV 99] Arvanitoyannis I.S., Totally and partially biodegradable polymer blends based on natural and synthetic macromolecules preparation, physical properties, and potential as food packaging materials , Journal of Macromolecular Science - Reviews in Macromolecular Chemistry Physics, vol. C39, no. 2, pp. 205-271, 1999. 

Is it possible to transfer a synthetic non-biodegradable polymer to a partially biodegradable polymer If so, how may this be done ... 

Czigany T, Morlin B, Mezey Z. Interfacial adhesion in fully and partially biodegradable polymer composites examined with microdroplet test and acoustic emission. Compos Interfaces 2007 14 869-878. 

Poly(HA) can be biodegraded to water and carbon dioxide or methane by a large variety of ubiquitous microorganisms present in many ecosystems (Fig. 1). This fairly easy bio degradability came as a surprise given the inertness of the water-insoluble, hydrophobic, and (partially) crystalline polymers. 

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... 

The properties of polymers are not only determined by their primary chemical structure but also by secondary structural elements. This is also tme for the process of biodegradation. In a first step, the secondary structures of the polymer, e.g., crystals in a partially crystalline polymer, have to be dissolved during the degradation process and temporarily flexible chains formed. 

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. 

During the search for efficient and ecologically justified waste-management concepts, the use of biodegradable polymer materials was repeatedly made a political demand. Next to the arguments of a partial solution to the waste-disposal problem by natural degradation, the conservation of the petrochemical resources, the reduction of C02-emission, and the use of renewable resources are a point of discussion. 

Cellulose blends with synthetic polymers also constitute an example of biodegradable polymer blends. Miscibility of cellulose with polyvinylpyrrolidone [Masson and Manley, 1991a], poly(4-vinyl pyridine) [Mason and Manley, 1991b], PAN [Nishio et al, 1987], PVAL [Nishio and Manley, 1988], and polyethyleneoxide (PEG) [Nishio et al., 1989] have been reported. Starch blends with commodity polymers have been commercialized as a low cost method to promote partial environmental degradability. While a defi-... 

The control of biodegradation rate is of critical importance for many applications of degradable polymers. Amorphous polyesters absorb water and hydrolyse much more rapidly than crystalline materials. Consequently, in partially crystalline polymers, hydrolysis occurs initially in the amorphous phase and continues more slowly in the crystalline phase. This selective degradation leads to an increase in crystallinity by chemicrystallisation. A very similar selective abiotic oxidation process occurs in the semi-crystalline polyolefins which fragment rapidly due to failure at the crystallite boundaries. 

Poly(8-caprolactone) (PCL), on the other hand, is a semi-ciystaUine biodegradable polymer. This material is commonly used as plasticizer. The P(3HB)/ PCL blend exhibited partial miscibility, however, the elongation at break was increased about 81 % in comparison with pure P(3HB) [43]. 

Table 2.1 Influence of starch/EAA ratio and of partial replacement of EAA with PE or PVOH on the tensile strength and elongation of starch/EAA films [83, 87], (Reproduced with permission from C. Bastioli, Handbook of Biodegradable Polymers, 2005. 2005, Smithers Rapra.)...

It is difficult to make a distinct classification of biodegradable polymers. Many authors have classified them according to their origin as natural or synthetic polymers. Both of these are subdivided into different classes based on the main linkages present in their structure. Thus completely biodegradable natural polymer subclasses include polysaccharides, polypeptides, polyesters, lipids, natural rubber and natural composites (wood). Partially biodegradable synthetic polymer subclasses include polyesters, polyur eas, polyurethanes, polyamides, poly( vinyl alcohol) and poly (ethylene glycol). 

It is environmentally important to perform a life cycle assessment analysis, not only for non-biodegradable polymers but also for partially biodegradable or even completely biodegradable polymers. Life cycle analysis (LCA) is a tool which helps in understanding the environmental impact associated with the products, processes and activities throughout the life of a polymer. The life cycle of vegetable oil-based polymers is shown in Rg. 2.6. Thus a complete LCA would include three separate but interrelated components, an inventory analysis, an impact analysis and an improvement analysis. 

As in petroleum-based polymers, most of the biodegradable polymer-based blends also show partial miscibility within their blends. In the miscibility perspective, this heterogeneous nature makes biodegradable polymer blends comparable with particulate-filled and fiber-reinforced polymer... 

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