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corn. In the long run, I expect that as technologies geared toward biomass-to-sugar conversion mature, CD will use these technologies to generate fermentable feedstocks.
Figure 11.1 and
Figure 11.2 outline the manufacturing steps of PLA. Carbon dioxide is fixed in crops to make starches. Agriprocessing businesses like corn wet-milling convert the starches to simple sugars. CD buys the sugar and uses it to ferment lactic acid. Using chemical processing techniques, lactic acid is converted efficiently to lactide, a ring-form dimer of lactic acid. Lactides are excellent polymerization starting materials because they are reactive and anhydrous, and they polymerize in the melt. PLA is made through ring-opening melt polymerization. The overall process is sufficiently efficient in terms of yield and energy that the products are economically viable.
PLA currently finds demand in three market areas: fibers, packaging, and chemical products. Significant research investment in product development has revealed product attributes that are valuable and the knowledge of how to best to use them in the marketplace. Fibers and packaging provide the strongest examples of how PLA attributes bring value to a market.
PLA fibers combine the comfort and feel of natural fibers with the performance of synthetics (
Table 11.1). The unique property spectrum of PLA fibers allows the creation of products with superior hand and touch, drape, comfort, moisture management, ultraviolet (UV) resistance, and resilience. Combining these performance features with the features of natural fibers enables PLA to be used in a wide spectrum of products including apparel, carpet, nonwoven fiberfill, and household and industrial markets (
PLA apparel, carpets, and nonwovens are already in test market. Consumers' reports indicate that the products actually work well, and they appreciate the products being made from renewable resources. Of course when consumers indicate that they appreciate a product made from renewable resources, they expect that there should be some measurable advantage regarding the environment compared to traditional petroleum-based products.
PLA polymers for packaging applications exhibit a balance of performance properties that are comparable and in certain cases superior, to traditional thermoplastics. PLA is useful in coated paper, films, rigid containers, bottles, and a variety of other packaging applications (
Figure 11.4). However, there are two specific packaging areas that have received initial focus—high-value films and rigid thermoformed containers. Functional properties and their benefits are listed in
The combination of functional properties provides the commercial drive for PLA. A close look at the properties listed in
Table 11.2 reveals that the technical attributes primarily benefit manufacturers and converters. The exceptions, renewable resources and compostability, are end-user and consumer-oriented attributes.
The market development for packaging is quite different than for fibers. PLA fibers benefit the consumer directly. For example, not only are the products—a shirt, for example—more comfortable (I can detect it myself as a consumer), they are also made starting from a natural product (a perception). So in fibers, the combination of direct consumer benefit and easily communicated perceptions helps to drive the potential of PLA.
In packaging market segments, consumers' concern for the environment has driven manufacturers to want to adopt new technologies. Led by Europe and Japan where environmental concerns receive a