Rubbers, biodegradable

Steinbuchel and co-workers, using rubbers as the sole source of carbon, found that NR and IR (synthetic polyisoprene rubber) biodegrade at a similar rate in the presence of Pseudomonas aeruginosa. NR gloves were 26% mineralised in 6 week compared with 21% for IR gloves. This slight difference may well have been due to the difference in the antioxidants used in the formulation, although these were not identified. It is clear, however that, contrary to the views of some environmentalists, there is no intrinsic difference between natural and synthetic polymers. 

Peroxidation of cw-poly(isoprene) leads in part to the formation of vicinal hydroperoxides as shown in Scheme 1. This process has been known for many years [5-7] but its full significance for rubber biodegradation has been recognised only recently. The low molar mass peroxidation products are rapidly biassimilated under environmental conditions. In addition, however, carbon dioxide and water, the normal end points of biodegradation, are also formed in significant quantities during abiotic oxidation and... 

Many environmentalists still believe that synthetie polymers eannot biodegrade in the environment. It is certainly true that some plasties may not degrade for a very long time even in sunlight. For example, properly stabiUsed PVC is widely used in out-door applications, such as window fiames which do not biodegrade for many decades, possibly centuries. At the other extreme, the poly(dienes) - for example c/s-poly(isoprene) in the form of latex rubber - biodegrades in a few months in soil (see section 12.2). The polyolefins lie somewhere between PVC and natural rubber. Biodegradable polyethylene (e.g. EPl TDPA ) shows a substantial induction period (IP) at 20 "C, whereas at 60 "C, the IP is very short. In a commercial weatherometer, the IP is even shorter." " ... 

Biodegradable Rubbers from Crosslinked Poly(HAMCL). 284... 

Current polymeric entubulization repair methods for peripheral nerve regeneration use various nondegradable and biodegradable materials. The most common nondegradable material investigated has been silicone rubber. Medical grade silicone rubber, polydimethylsiloxane, maintains its shape and can be filled with neurotrophic factors or extracellular... 

Li K, Gu J-D (2004) Biodegradation of di- -butyl phthalate by mangrove microorganism Rhodococcus rubber IK. Chin J Appl Ecol 16 1566-1568 (in Chinese)... 

Li J, Gu J-D, Pan L (2005a) Transformation of dimethyl phthalate, dimethyl isophthalate and dimethyl terephthalate by Rhodococcus rubber Sa and modeling the processes using the modified Gompertz model. Int Biodeterior Biodegrad 55 223-232... 

Renewable raw materials are made or derived from short-term renewable sources (one to a few years or a few tens of years) such as plants, trees, wood wastes and other agricultural products. Not all these materials are necessarily biodegradable. Natural rubber, for example, comes from the latex of a tree (Hevea brasiliensis) and is not biodegradable. Renewable materials are often considered as opposites to fossil sources such as petroleum that are not renewable on a human timescale. On the other hand, some synthesized plastics such as certain polyesters are biodegradable. 

Uses Solvent standardized hydrocarbon manufacturing paraffin products biodegradable detergents Jet fuel research rubber industry paper processing industry distillation chaser component of gasoline and similar fuels organic synthesis. 

Starch has been considered an attractive raw material for polymer applications for almost 200 years. Kirchoff s discovery in 1811 that treatment of starch with an acid yields a sweet substance was an unexpected result of the search for a low-cost substitute for natural rubber.1 Considerable research in the development of starch-based polymer materials has been stimulated by the facts that starch is produced from wide variety of sources, is an annually renewable resource and is inherently biodegradable. 

The Sesame is designed so that molders can use a smaller runner and sprue, which gives them more control over the amount of plastic and pressure used to form the part itself. A smaller runner and sprue also means less material waste. While screw-and-barrel systems waste as much as 99.7% of the shot material, the Sesame wastes less than 80%. This is particularly important when molding expensive materials like biodegradable plastics, which cost as much as 10 per gram. The Sesame can handle any type of moldable plastic, as well as silicone rubber. Super-small medical parts that have been molded by the machine include ... 

In examples Cy-Am 1-5 of Table 7 the monomers used were 2-propeneni-trile (107-13-1) and 2-propenamide (79-06-1). In examples Cy 1-5 of Table 7, the monomer used was 2-propenenitrile (107-13-1). The compounds in the first group are water-absorbing agents whereas those in the second group are thermoplastics and biodegradable plastics [56]. In examples MBuD 1-3 of Table 7, the monomer used was 2-methyl-1,3-butadiene (78-79-5). These materials are uncrosslinked elastomers and potential rubber additives. In examples MPrPe 1-9 of Table 7, the monomer used was 2-methyl-2-oxy-3-oxopent-4-ene (80-62-6). These materials are thermoplastics and biodegradable plastics [57]. 

The most fundamental classification of polymers is whether they are naturally occurring or synthetic. Common natural polymers (often referred to as biopolymers) include macromolecules such as polysaccharides e.g., starches, sugars, cellulose, gums, etc.), proteins e.g., enzymes), fibers e.g., wool, silk, cotton), polyisoprenes e.g., natural rubber), and nucleic acids e.g., RNA, DNA). The synthesis of biodegradable polymers from natural biopolymer sources is an area of increasing interest, due to dwindling world petroleum supplies and disposal concerns. 

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