The future growth opportunities for lactic acid are in its use as a feedstock for potentially large-volume applications. In Table I, these applications are classified into four categories — biodegradable polymers, oxygenated chemicals, "Green” chemicals/solvents, and plant-growth regulators. The overall size of this opportunity, both in terms of mass/volume and product sales value, is substantial. For the U. S. markets, this could be approximately 6.4-8.4 x 109 lb/yr (2.9-4.0 x 106

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tons/yr), with sales volume between approximately $4.3-6.2 x 10 /yr. The volume and selling price projections for the new products (i. e., the degradable plastics, "green" chemicals, and derivatives) are made on the basis of several published studies by Battelle and others and some internal Argonne estimates. It should be noted that the high volumes can be reached only when the prices are within the acceptable ranges (Table I) and vice versa. The list in Table I is by no means comprehensive nor would all these products (particularly the oxychemicals) be derived from lactic acid in the near future. It should be noted, however, that recently a large U. S. agriprocessing company, Cargill, has announced a potential plaht of 250 x 106 lb/yr by 1997/1998 (5), substantiating that large-volume, economical manufacturing of lactic acid may be feasible with new technologies and for new or existing products.

Polymers of lactic acids are biodegradable thermoplastics. A fairly wide range of properties are obtainable by copolymerization with other functional monomers, such as glycolide, caprolactone, and polyether polyols. The polymers are transparent, which is important for packaging applications. They offer a good shelf life because they degrade slowly by hydrolysis, which can be controlled by adjusting the composition and molecular weight. These have potential uses in a wide variety of consumer products, such as paper coatings, films, moulded articles, foamed articles, and fibers. Some of the published information on some of the properties of lactic copolymers that approach those of large-volume, petroleum-derived polymers (such as polystyrene, flexible polyvinyl chloride [PVC], and vinylidene chloride) are summarized in the article of Lipinsky and Sinclair (7). There are numerous patents and articles on lactic acid polymers and copolymers, their properties, potential uses, and processes that date back to the early work by Carothers at DuPont. A discussion of this work is beyond the scope of this article. Several reference articles and patents (12-15) can provide the reader with a basis for further information.

Among the other new product opportunities, the use of lactate esters as "green” solvents is substantial because they are high-boiling (nonvolatile), nontoxic, and degradable compounds. With increasing consumer and political consciousness with environmentally sound products, the use of these solvents as replacements for other solvents or cleaners could be a very important expansion opportunity for lactic acid. The estimates of the volume of these (Table I) are based on typical volumes and lower prices than several intermediate volume non-volatile solvents, such as n-methyl pyrrolidone, di-basic esters and such. Low-molecular-weight polymers of L-lactic acid (degree of polymerization [dp] 2-10) have been recently discovered to stimulate plant growth in a variety of crops and fruits when applied at a low level (16-17). These findings may lead to specialized products and formulations that would incorporate L-polylactic acid as or into controlled release or degradable mulch films for large-scale agricultural applications.