Polylactic acid, biodegradation

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. 

Table 6.1 shows global consumption of polylactic acid biodegradable polymers by major world region for the years 2000, 2005 and 2010. 

World consumption of polylactic acid biodegradable polymers has increased significantly over the last five years as major suppliers such as Nature Works have brought their 140,000 tonnes per annum plant fully on stream. In 2005, world consumption of PLA amounted to 35,800 tonnes against 8,700 tonnes five years earlier. During the period 2005-2010, PLA consumption is forecast to reach 89,500 tonnes, which represents a compound annual growth rate of 20.1%. 

Polylactic acid Biodegradable polyester used in degradable plastic products. 

J. B., Polylactic acid as a biodegradable carrier for contraceptive steroids. Contraception, 8, 227, 1973. 

Polylactic acid (PLA) has been produced for many years as a high-value material for use in medical applications such as dissolvable stitches and controlled release devices, because of the high production costs. The very low toxicity and biodegradability within the body made PLA the polymer of choice for such applications. In theory PLA should be relatively simple to produce by simple condensation polymerization of lactic acid. Unfortunately, in practice, a competing depolymerization process takes place to produce the cyclic lactide (Scheme 6.10). As the degree of polymerization increases the rate slows down until the rates of depolymerization and polymerization are the same. This equilibrium is achieved before commercially useful molecular weights of PLA have been formed. 

The use of biodegradable polymers, especially polylactic acid (PLA), in oral solid dosage forms has been reported in the literature. PLA has been used as a matrix for phenobarbital tablets (9). Similarly, the use of polylactide as a matrix for oral dosage form of naproxen has also been reported (10). 

It polymerises to form the polymer, polylactic acid (PLA) which is biodegradable, a Suggest two advantages that PLA has compared with a polymer made from petroleum. [2]... 

DL-Polylactic acid, for the most part, was found to erode in about 12 months. Slow degradation of DL-polylactic acid often becomes a limitation on its use. This rate can be accelerated appreciably by copolymerizing with up to 50 mol% glycolide to yield complete erosion in as fast as 2 to 3 weeks. Incorporation of glycolide into the polylactide chain alters crystallinity, solubility, biodegradation rate, and water uptake of the polymer. 

Outright, D. E., and Hunsuck, E. E. Tissue reaction to the biodegradable polylactic acid suture. Oral Surg Oral Med Oral Pathol 31(1) 134-139, 1971. 

Schmidmaier G, Stemberger A, Ait E, et al. Non-liner time release characteristics of a biodegradable polylactic acid coating releasing PEG hirudin and a PGI2 analog [abstr], Eur Heart J 1997 18(suppl) 571. 

Alt E, Beilharz C, Preter G, et al. Biodegradable stent coating with polylactic acid, hirudin and prostacyclin reduces restenosis [abstr], J Am Coll Cardiol 1997 29 238A. 

Lactic acid is an important chemical that has wide applications in food, pharmaceutical, cosmetic, and chemical industries. There are increasing interests in production of lactate esters and biodegradable polylactic acid (PLA) from lactic acid. Lactate esters are a relatively new family of solvents with specific properties. They are considered safe and are biodegradable (1). In many situations they can replace toxic solvents. Their functions vary from that of intermediates in chemical reactions to solvents in ink formulations and cleaning applications (2). PLA has been widely used in medical implants, sutures, and drug-delivery systems because of its capacity to dissolve over time (3-5). PLA also can be used in products such as plant pots, disposable diapers, and textile fabrics. 

Another way to control the release of biocides is to entrap them into a matrix that is slowly hydrolyzed, e.g., into polylactic acid or other polyesters [104, 105] or degradable polyelectrolyte multilayers [106], By choosing a matrix that is degradable by a specific enzyme, the location of release in the body can be controlled. An example of this approach, which is very common for drug release but rarely used for biocides, is fluoroquinolone-modified biodegradable polyurethane that releases the antibiotic ciprofloxazin upon degradation catalyzed by the enzyme cholesterol esterase [107],... 

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