As new biodegradable polymers and their packaging applications are emerging, there is a need to address their environmental performance. In particular, there is a need to understand the time required for their complete disintegration, before these materials are deployed in commercial composting processes. Standards developed by ASTM and ISO evaluate the biodegradation of biodegradable plastic materials in simulated controlled composting conditions. However, a more detailed understanding of the biodegradation of complete packages is needed in order to have a successful composting operation. This paper investigates the biodegradation performance of polylactide (PLA) bottles under simulated composting conditions according to ASTM and ISO standards, and these results are compared with a novel method of evaluating package biodegradation in real composting conditions. Two simulated composting methods were used in this study to assess biodegradability of PLA bottles: (a) a cumulative measurement respirometric (CMR) system and (b) a gravimetric measurement respirometric (GMR) system. Both CMR and GMR systems showed similar trends of biodegradation for PLA bottles and at the end of the 58th day the mineralization was 84.2±0.9% and 77.8±10.4%, respectively. PLA bottle biodegradation in real composting conditions was correlated to their breakdown and variation in molecular weight. Molecular weight of 4100 Da was obtained for PLA bottles in real composting conditions on the 30th day. The biodegradation observed for PLA bottles in both conditions explored in this study matches well with theoretical degradation and biodegradation mechanisms; however, biodegradation variability exists in both conditions and is discussed in this paper.
[1]
Susan Selke,et al.
An overview of polylactides as packaging materials.
,
2004,
Macromolecular bioscience.
[2]
R. Auras,et al.
Degradation of Commercial Biodegradable Packages under Real Composting and Ambient Exposure Conditions
,
2006
.
[3]
M. Funabashi,et al.
Biodegradation of poly(lactic acid) powders proposed as the reference test materials for the international standard of biodegradation evaluation methods
,
2006
.
[4]
Gaurav Kale,et al.
Compostability of bioplastic packaging materials: an overview.
,
2007,
Macromolecular bioscience.
[5]
D. Pichora,et al.
An Investigation of Poly(lactic acid) Degradation
,
1994
.
[6]
Ramani Narayan.
Drivers & rationale for use of biobased materials based on life cycle assessment (LCA)
,
2004
.
[7]
R. T. Fernandez,et al.
Development of an automatic laboratory-scale respirometric system to measure polymer biodegradability
,
2006
.
[8]
R. Auras,et al.
Comparison of the degradability of poly(lactide) packages in composting and ambient exposure conditions
,
2007
.