The development and challenges of poly (lactic acid) and poly (glycolic acid)

Bio-plastics have gained tremendous attention, due to the increasing environmental pressure on global warming and plastic pollution. Among them, poly (lactic acid) (PLA) is both bio-based and bio-degradable, which has been widely used in many disposable packaging applications. The global market for PLA demand doubles every 3–4 years, as estimated by Jem's law.Compared to traditional petroleum-based plastics, PLA is more expensive and usually has less mechanical and physical properties. The recent compounding efforts and the commercialization of D(−) lactic acid and its polymer PDLA have the potential to improve the mechanical and thermal characteristics of PLA (e.g. by forming stereocomplex PLA) for applications in high-end markets. However, the usage of PLA in some other applications is still limited.With a structure similar to PLA, poly (glycolic acid) (PGA) has promising characteristics such as good biodegradability and barrier properties, which is potentially a beneficial supplement to PLA. The modification of PLA with PGA can be achieved via co-polymerization, physical blending and multilayer lamination. PGA and its combination with PLA have been widely studied in bio-medical applications, but not been well developed at large scales due to its relatively high production cost. In this case, the development of novel production technology and the advent of government regulations are the key drivers for the global transition towards bioplastics. Recently, multiple governmental regulations have been released that restrict the use of traditional plastics and facilitate bio-degradable plastic applications. PGA can be derived from industrial waste gases using an innovative production technology, which reduces carbon emissions and its production cost. By developing the production and compounding technology, PGA can be combined with PLA to play an essential role for a sustainable and environmental friendly plastic industry, especially for single-used products requiring fast degradation at room temperature or in the nature environment. Keywords: Poly (lactic acid), Poly (glycolic acid), Modification of PLA with PGA, Plastic pollution, Global warming