Industrial Composting of Poly(Lactic Acid) Bottles

Abstract

In order to better understand the end of life scenario potential of poly(lactic acid) (PLA) packaging to reduce waste through composting when properly disposed, this study aimed to determine the rate at which 473 mL (16 oz) PLA bottles with and without associated high density polyethylene (HDPE) caps and polypropylene (PP) labels decomposed in an industrial compost pile. Temperature, moisture content, and pH levels of the compost pile were recorded throughout the study to determine their effects on the rate of decomposition and to ensure optimal conditions were met. Analyses performed at weeks 2, 4, and 8 showed that from week 2, a 94 % reduction of mass and weight average molecular weight occurred, along with a complete loss of structural integrity. PLA bottles without caps and labels were considered to be decomposed completely by week 4, while the bottles with the HDPE caps and PP labels showed plastic residues until week 8. The caps and labels acted as a barrier that slowed the rate of biodegradation. This study showed that PLA bottles can be composted in industrial composting facilities in 30–45 days, and it is recommended to remove all caps and labels. The results further indicated that if a proper infrastructure is put in place to allow large scale composting of PLA, this packaging polymer could have a significant impact on reducing municipal solid waste.

Toward Sustainable Wearable Electronic Textiles

“…95 According to standards developed by the Biodegradable Products Institute, 96 PLA is an excellent biodegradable material as well as a green bio-based polymer. However, PLA will only degrade into carbon dioxide and water within a controlled composting environment, 97 making it more sustainable than other types of plastics derived from fossil fuels and any other bio-based and biodegradable polymers. PLA is one of the most prevalent pervasive bio-based polymers for scores of usages, with diverse end-of-life (EoL) options (Figure 4), including recycling, landfilling, and industrial composting.…”

The Chemical Recycling of PLA: A Review

“…30 days under such conditions [55,59]. The products of composting are CO2 and water, the amount of carbon dioxide emitted being offset by the initial uptake in the production of PLA feedstocks [40].…”

“…Near infrared imaging is a potential solution to differentiate between these materials [54]. PLA can be efficiently composted under industrial conditions, requiring temperatures around that of the polymer's Tg (60 °C) and high relative humidity [55][56][57][58]. Degradation can take as little as Scheme 1.…”

“…PLA can be efficiently composted under industrial conditions, requiring temperatures around that of the polymer's T g (60 • C) and high relative humidity [55][56][57][58]. Degradation can take as little as 30 days under such conditions [55,59]. The products of composting are CO 2 and water, the amount of carbon dioxide emitted being offset by the initial uptake in the production of PLA feedstocks [40].…”

Preparation and Characterization of Poly(lactic acid) with Different Molecular Weights by Thermal Hydrolysis

“…Poly(lactic acid) (PLA) is a kind of degradable thermoplastic polymer and has been widely used in the fields of biomedical and environmental areas because of its excellent biodegradable property, fairly good biocompatibility and moldability [1][2][3]. Different application fields, such as packaging material [4,5], tissue engineering material [6], hot melt adhesive [7], fiber [8,9] and drug release carrier [10,11], require PLA to be of different molecular weight and molecular weight distribution which are the internal factors impacting the molecular structure and properties. Typically, the molecular weight of PLA is determined by the polymerization method, i.e.…”