6.1 Introduction

Polylactic acid (PLA) is a biodegradable polymer derived from lactic acid. It is a highly versatile material and is made from 100% renewable resources such as corn, sugar beet, wheat and other starch-rich products. PLA exhibits many properties that are equivalent to or better than many petroleum-based plastics, which makes it suitable for a variety of applications. PLA is available either in a rigid or flexible form and can be co-polymerised with other materials. It is suitable for a wide range of processing technologies including injection moulding, film and sheet extrusion, blow moulding, thermoforming and fibre spinning.

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.

The formation of Cargill Dow Polymers, a joint venture between Cargill, the agricultural company, and Dow Chemicals in 1997, was one of the most significant developments in the evolution of the biodegradable polymers market. Cargill Dow, which is now trading as NatureWorks LLC, began commercial scale production of their NatureWorks polylactic acid (PLA) based biopolymers in Blair, Nebraska, USA in 1997. The company has since invested in the development of a large scale 140,000 tonnes per annum facility for...