Polylactic acid , production

Polylactic acid Production uses 30-50% less fossil energy and generates 50-70% less CO2 emissions than PBP. Competitive use of water with the best performing PBP, recyclable, compostable at temperatures above 60"C... 

Dainippon Ink Chemicals Inc. offers a polyester based impact modifier specifically for use in the biodegradable polymer, polylactic acid. Arakawa Chemical has developed biodegradable plasticisers for what is expected to be a rapidly expanding market associated with Cargill Dow s polylactic acid product. 

It is essential to neutralize any strong acid present before distilling lactic esters otherwise, condensation by ester interchange occurs, with liberation of alcohol and production of polylactic acid, a linear polyester. Other neutralizing agents, such as alkali or alkaline-earth hydroxides or carbonates, doubtless could be used satisfactorily instead of sodium acetate. 

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. 

Table 4 A Partial List of Marketed Drug Delivery Products Utilizing Polylactic Acid or Poly(lactic-co-glycolic) Acid Polymers...

Fossil Fuel and Solar Energy Contributions to the Production of Polyethylene (PE), Polylactic acid (PLA), and Polyhydroxyalkanoate (PHA) in kg Fuel/kg Product... 

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. 

In order to decrease human consumption of petroleum, chemists have investigated methods for producing polymers from renewable resources such as biomass. Nature Works polylactic acid (PLA) is a polymer of naturally occurring lactic acid (LA), and LA can be produced from the fermentation of corn. The goal is to eventually manufacture this polymer from waste biomass. Another advantage of PLA is that, unlike most synthetic polymers which litter the landscape and pack landfills, it is biodegradable. PLA can also be easily recycled by conversion back into LA. It can replace many petroleum-based polymers in products such as carpets, bags, cups, and textile fibers. 

Chemically-Controlled Systems. In these systems, the polymer matrix contains chemically-labile bonds. On exposure to water or enzymes the bonds hydrolyze, erode the three dimensional structure of the polymer and release the incorporated reagent into the surrounding medium. Depending on the polymer used, the erosion products may act as interferences, such as by altering the pH of the solution. Examples of these systems are polyglycolic acid (PGA) and a polyglycolic acid - polylactic acid (PGA/PLA) copolymer. PGA hydrolyzes to hydroxyacetic acid, and PGA/PLA hydrolyzes to lactic acid and hydroxyacetic acid. Other chemically-controlled systems are based on polyorthoesters, polycaprolactones, polyaminoacids, and polyanhydrides. 

The first step will be to separate the seed from the straw (collection will obviously occur simultaneously, to minimise energy use and labour cost). The seeds may then be processed to produce starch and a wide variety of products, including ethanol and bioplastics (e.g. polylactic acid). The straw can be processed to products via various conversion processes, as described above for a lignocellulosic feedstock biorefinery. 

Biobased polymers from renewable materials have received increased attention recently. Lactate is a building block for bio-based polymers. In the United States, production of lactic acid is greater than 50,000 metric tons/yr and projected to increase exponentially to replace petroleum-based polymers. Domestic lactate is currently manufactured from corn starch using the filamentous fungus Rhizopus oryzae and selected species of lactic acid bacteria. The produced lactic acid can then be polymerized into polylactic acid (PLA) which has many applications (Hatti-Kaul et al., 2007). However, so far, no facility is built to use biomass derived sugars for lactic acid production. More research needs to be done to develop microbes using biomass derived sugars for lactate production. 

P. V. Bonsignore, Production of high molecular weight polylactic acid, US Patent 5470944, assigned to ARCH Development Corporation, November 28 1995. 

Polylactic acid (PLA) is a biodegradable polymer derived from lactic acid. It is a highly versatile material and is made from 100% renewable resources like corn, sugar beet, wheat and other starch-rich products. Polylactic acid exhibits many properties that are equivalent to or better than many petroleum-based plastics, which makes it suitable for a variety of applications. 

Polylactic acid has been around for many decades. In 1932, Wallace Carothers, a scientist for DuPont, produced a low molecular weight product by heating lactic acid under a vacuum. In 1954, after further refinements, DuPont patented Carothers process. 

The major classes of biopolymer, starch and starch blends, polylactic acid (PLA) and aliphatic-aromatic co-polyesters, are now being used in a wide variety of niche applications, particularly for manufacture of rigid and flexible packaging, bags and sacks and foodservice products. However, market volumes for biopolymers remain extremely low compared with standard petrochemical-based plastics. For example, biopolymer consumption accounted for just 0.14% of total thermoplastics consumption in Western Europe for 2005. 

Polylactic acid was first discovered in the 1930s when a DuPont scientist, Wallace Caruthers, produced a low molecular weight PLA product. In 1954, DuPont patented Carothers process. Initially the focus was on the manufacture of medical grade applications due to the high cost of the polymer, but advances in fermentation of glucose, which forms lactic acid, has dramatically lowered the cost of producing lactic acid and significantly increased interest in the polymer. 

Another Japanese consumer electronics company, NEC, plans to adopt PLA biopolymers for its cellphones and personal computers in order to achieve product differentiation. Impact strength, heat deformation resistance and durability are required for cellphones and the company has developed a kenaf-reinforced polylactic acid that meets these requirements. Plans now call for the reinforced resin to be given non-phosphorous, non-halogen flame retardancy, and then applied to notebook personal computer housings starting in 2007. 

In 2005, Japanese company Kaneka developed the first beads-process, foamed resin moulded product, which is based on polylactic acid. The new KanePearl product has the strength and shock-absorbing properties of existing beads-process, foamed polystyrene products. 

Cargill Dow Polymers LLC started up its first commercial-scale plant for polylactic acid (PLA) at Blair, Nebraska, in the US in 2002. The unit has planned capacity to produce 136,000 tonnes per annum. Until then, the pilot production capacity for PLA was only 4,000 tonnes per annum. 

Japanese company NEC has developed a plant-derived bioplastic whose main component is polylactic acid. It is said to possess the world s best flame retardance for a product of this type. This has been achieved without the use of halogenated or phosphorous flame retardants. NEC has applied proprietary property-modifying additives such as inorganic heat absorbants, high flow modifiers and impact modifiers to realise the bioplastic. The material conforms to the UL94 5V standard, which means it can be utilised in a wide variety of electronic products, including personal computer housing. 

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