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Biodegradable Materials

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From 04/08/2015  to 4/19/2012

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Biodegradable Materials: Applications

Biodegradable Polyesters

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Notes  (5 entries)

1. Description

 “Biodegradation or biotic degradation or biotic decomposition is the chemical dissolution of materials by bacteria or other biological means. The term is often used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation) and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements. Organic material can be degraded aerobically with oxygen, or anaerobically, without oxygen. A term related to biodegradation is biomineralisation, in which organic matter is converted into minerals. Biosurfactant, an extracellular surfactant secreted by microorganisms, enhances the biodegradation process.”

Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms. Some microorganisms have a naturally occurring, microbial catabolic diversity to degrade, transform or accumulate a huge range of compounds including hydrocarbons (e.g. oil), polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), pharmaceutical substances, radionuclides and metals. Major methodological breakthroughs in microbial biodegradation have enabled detailed genomic, metagenomic, proteomic, bioinformatic and other high-throughput analyses of environmentally relevant microorganisms providing unprecedented insights into key biodegradative pathways and the ability of microorganisms to adapt to changing environmental conditions.  Products that contain biodegradable matter and non-biodegradable matter are often marketed as biodegradable.”

(Wikipedia, Biodegradation, 4/23/2012)

2. Applications

“Biodegradable polymers have found use in a wide variety of applications ranging from trash bags that decompose in landfills to implantable medical devices that biodegrade in the body.  Most of these applications require that such polymers have adequate physical properties and stability to provide for suitable handling and utility prior to being subjected to end use conditions that promote biodegradation.  Further, it is often preferable that these same polymers rapidly or controllably biodegrade once subjected to such end use conditions.  In addition, it is often desired that biodegradable polymers used for implantable medical devices be converted under physiological conditions to materials that do not irritate or harm the surrounding tissue.  Many biodegradable polymers known in the art lack the combination of physical and/or chemical properties desired to meet the needs for specific applications.”

 [Zhang, Lyu and Schley, US Patent 8,129,477 (3/6/2012)]

3. Natural Materials

“Biodegradable materials originating from a natural source, for example Type I collagen, hyaluronic acid derivatives, polysaccharides and chitosan, have been used in various medical applications. These biomaterials have some disadvantages e.g. the properties of natural polymers are difficult to control; they may have batch to batch variations, and they are generally more expensive than synthetic materials. Also, biodegradable material of natural sources, especially of animal origin, is not preferred to be used, because of the biological hazards associated with its use. Synthetic materials usually do not suffer from these disadvantages.” [Hissink et al, US Patent 8,187,2254 (5/29/2012)]

4.Properties

“Conventional biodegradable plastics are insufficient in properties such as heat resistance and the like as compared with general plastics, in some cases. Therefore, for the purpose of improving the properties of a biodegradable plastic, such as heat resistance and the like, Japanese Patent Application Laid-Open (JP-A) No. 6-192375 suggests a technology in which polycaprolactone is cross-linked with an isocyanate, and the heat resistance of a biodegradable plastic is improved by introducing a cross-linked structure of a covalent bond.

In the above-mentioned conventional technology, the heat resistance and the like of a biodegradable plastic are improved by a cross-linked structure, however, there are a possibility of decrease in flowability in heat melting, a possibility of insufficient moldability, and a possibility of decrease in biodegradability. Particularly, in the case of a highly cross-linked biodegradable plastic, when this is once molded, it behaves as if a thermosetting resin, and even if this is to be recovered and recycled, sufficient heat melting is not attained in second and later moldings, leading to difficult recycling, in some cases.

[Inoue, Yamashiro and Iji, US Patent 8,258,254 (9/4/2012)]

5. Biodegradable Polycarbonates

Biodegradable polymers are badly needed in an environmentally sensitive world, weary of growing landfills and atmospheric pollution.  Polycarbonates are very useful but are not biodegradable nor renewable.  In addition, using CO2 as a raw material, removes a warming gas from the atmosphere and is desirable.  

Jeong et al produced a polycarbonate by copolymerizing an epoxy with CO2 using cobalt(III) or chromium(III) catalysts. These catalysts are unique with high activities.  The polymerization process can be batch, semibatch, or continuous.  The resulting polymer number-average molecular weight (Mn) is 5,000 to 1,000,000 with molecular weight distributions (Mw/Mn) of 1.05 to 4.0.  The polycarbonate contains 80% or more carbonate linkages and is easily degradable with no residue or soot from combustion.  The materials are useful for packaging, insulation and coatings.

US Patent 8,981,043 (March 17, 2015), “Catalytic System for CO2/Epoxide Copolymerization,” Jisu Jeong, Sujith Sudevan, Myungahn Ok, Jieun Yoo, BunYeoul Lee, and SungJae Na (SK Innovation Co., Ltd., Seoul, South Korea).

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Interested!!
Bookmark this page to follow future developments!.
(RDC 6/5/2012)

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Roger D. Corneliussen
Editor
www.maropolymeronline.com

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E-Mail: cornelrd@bee.net  

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Copyright 2012 by Roger D. Corneliussen.
No part of this transmission is to be duplicated in any manner or forwarded by electronic mail without the express written permission of Roger D. Corneliussen
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* Date of latest addition; date of first entry is 4/19/2012.