Corn starch is the raw material used in the synthesis of polylactic acid (PLA), a bioplastic that came to being in a bid to quell carbon emissions during the production of petroleum-based plastics. PLA is a thermoplastic, high-strength, high-modulus polymer that can be made annually from renewable sources to yield articles. PLA polymers are considered biodegradable and compostable.
PLA has a low melting point, so it is mostly used for cold applications. For items that have to withstand higher temperatures such as cutlery or lids for hot beverages however, a crystallised form called CPLA is a sustainable alternative.
CPLA or Crystallized Poly Lactic Acid, is a combination of PLA (70-80%), chalk (20-30%) and other biodegradable additives. Through the crystallization of PLA, CPLA products can withstand high temperatures of up to 85°C without deforming. Once crystallized, CPLA is no longer transparent, but matte white. For black CPLA cutlery and coffee cups lids, charcoal is added to create the black colour. This does not conflict with overall composting properties of CPLA.
Corn is a tender and warm-season annual and a member of the grass family that can grow from 4 to 12 feet tall. It is in other words a very fast renewable resource for which no trees have to be cut down. As such, PLA & CPLA are readily available as a by-product of corn production, does not require additional cultivation areas and has no impact on the area of forests. It can take from 60 to 100 days to reach harvest depending upon the variety and the amount of heat during the growing season.
Corn does require a significant amount of water and is also nitrogen-heavy. As such, proper soil management is necessary.